TY  - JOUR
AU  - Nikačević, Nikola
AU  - Jovanović, Mina
AU  - Petkovska, Menka
PY  - 2011
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1958
AB  - A steady-state, one-dimensional mathematical model for a multifunctional reactor with in situ adsorption for ammonia synthesis is developed. The model represents integrated ammonia catalytic equilibrium reaction with ammonia adsorption in a co-current gas-flowing solids-fixed bed reactor (GFSFBR). The model was used for simulating the performance of an industrial-scale reactor, which confirmed that the reactant conversion is significantly higher in the multifunctional reactor in comparison to the conventional reactor under optimal conditions. The analysis of the simulation results shows that the conversion in the GFSFBR stays higher than those in the classical reactor even if much lower temperatures and pressures are used.
PB  - Elsevier, Amsterdam
T2  - Chemical Engineering Research & Design
T1  - Enhanced ammonia synthesis in multifunctional reactor with in situ adsorption
EP  - 404
IS  - 4A
SP  - 398
VL  - 89
DO  - 10.1016/j.cherd.2010.08.011
ER  - 

@article{
author = "Nikačević, Nikola and Jovanović, Mina and Petkovska, Menka",
year = "2011",
abstract = "A steady-state, one-dimensional mathematical model for a multifunctional reactor with in situ adsorption for ammonia synthesis is developed. The model represents integrated ammonia catalytic equilibrium reaction with ammonia adsorption in a co-current gas-flowing solids-fixed bed reactor (GFSFBR). The model was used for simulating the performance of an industrial-scale reactor, which confirmed that the reactant conversion is significantly higher in the multifunctional reactor in comparison to the conventional reactor under optimal conditions. The analysis of the simulation results shows that the conversion in the GFSFBR stays higher than those in the classical reactor even if much lower temperatures and pressures are used.",
publisher = "Elsevier, Amsterdam",
journal = "Chemical Engineering Research & Design",
title = "Enhanced ammonia synthesis in multifunctional reactor with in situ adsorption",
pages = "404-398",
number = "4A",
volume = "89",
doi = "10.1016/j.cherd.2010.08.011"
}

Nikačević, N., Jovanović, M.,& Petkovska, M.. (2011). Enhanced ammonia synthesis in multifunctional reactor with in situ adsorption. in Chemical Engineering Research & Design
Elsevier, Amsterdam., 89(4A), 398-404.
https://doi.org/10.1016/j.cherd.2010.08.011

Nikačević N, Jovanović M, Petkovska M. Enhanced ammonia synthesis in multifunctional reactor with in situ adsorption. in Chemical Engineering Research & Design. 2011;89(4A):398-404.
doi:10.1016/j.cherd.2010.08.011 .

Nikačević, Nikola, Jovanović, Mina, Petkovska, Menka, "Enhanced ammonia synthesis in multifunctional reactor with in situ adsorption" in Chemical Engineering Research & Design, 89, no. 4A (2011):398-404,
https://doi.org/10.1016/j.cherd.2010.08.011 . .

TY  - JOUR
AU  - Petkovska, Menka
AU  - Marković, A.
AU  - Lazar, M.
AU  - Seidel-Morgenstern, Andreas
PY  - 2011
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1931
AB  - Theoretical development of a new experimental method for investigation of mass transport in porous membranes, based on the principle of the modified Wicke-Kallenbach diffusion cell and the nonlinear frequency response analysis is presented. The method is developed to analyze the transport of a binary gas mixture in a porous membrane. The mixture is assumed to consist of one adsorbable and one inert component. Complex mass transfer mechanism in the membrane, where bulk or transition diffusion in the pore volume and surface diffusion take place in parallel, is assumed. Starting from the basic mathematical model equations and following a rather standardized procedure, the frequency response functions (FRFs) up to the second order are derived. Based on the derived FRFs, correlations between some characteristic features of these functions on one side, and the whole set of equilibrium and transport parameters of the system, on the other, are established. As the FRFs can be estimated directly from different harmonics of the measured outputs, these correlations give a complete theoretical basis for the proposed experimental method. The method is illustrated by quantifying the transport of helium (inert gas) and C3H8 and CO2 (adsorbable gases) through a porous Vycor glass membrane.
PB  - Springer, New York
T2  - Adsorption-Journal of the International Adsorption Society
T1  - Investigation of gas transport through porous membranes based on nonlinear frequency response analysis
EP  - 91
IS  - 1
SP  - 75
VL  - 17
DO  - 10.1007/s10450-010-9293-3
ER  - 

@article{
author = "Petkovska, Menka and Marković, A. and Lazar, M. and Seidel-Morgenstern, Andreas",
year = "2011",
abstract = "Theoretical development of a new experimental method for investigation of mass transport in porous membranes, based on the principle of the modified Wicke-Kallenbach diffusion cell and the nonlinear frequency response analysis is presented. The method is developed to analyze the transport of a binary gas mixture in a porous membrane. The mixture is assumed to consist of one adsorbable and one inert component. Complex mass transfer mechanism in the membrane, where bulk or transition diffusion in the pore volume and surface diffusion take place in parallel, is assumed. Starting from the basic mathematical model equations and following a rather standardized procedure, the frequency response functions (FRFs) up to the second order are derived. Based on the derived FRFs, correlations between some characteristic features of these functions on one side, and the whole set of equilibrium and transport parameters of the system, on the other, are established. As the FRFs can be estimated directly from different harmonics of the measured outputs, these correlations give a complete theoretical basis for the proposed experimental method. The method is illustrated by quantifying the transport of helium (inert gas) and C3H8 and CO2 (adsorbable gases) through a porous Vycor glass membrane.",
publisher = "Springer, New York",
journal = "Adsorption-Journal of the International Adsorption Society",
title = "Investigation of gas transport through porous membranes based on nonlinear frequency response analysis",
pages = "91-75",
number = "1",
volume = "17",
doi = "10.1007/s10450-010-9293-3"
}

Petkovska, M., Marković, A., Lazar, M.,& Seidel-Morgenstern, A.. (2011). Investigation of gas transport through porous membranes based on nonlinear frequency response analysis. in Adsorption-Journal of the International Adsorption Society
Springer, New York., 17(1), 75-91.
https://doi.org/10.1007/s10450-010-9293-3

Petkovska M, Marković A, Lazar M, Seidel-Morgenstern A. Investigation of gas transport through porous membranes based on nonlinear frequency response analysis. in Adsorption-Journal of the International Adsorption Society. 2011;17(1):75-91.
doi:10.1007/s10450-010-9293-3 .

Petkovska, Menka, Marković, A., Lazar, M., Seidel-Morgenstern, Andreas, "Investigation of gas transport through porous membranes based on nonlinear frequency response analysis" in Adsorption-Journal of the International Adsorption Society, 17, no. 1 (2011):75-91,
https://doi.org/10.1007/s10450-010-9293-3 . .

TY  - JOUR
AU  - Arsenijević, Zorana
AU  - Grbavčić, Željko
AU  - Grbić, Boško
AU  - Radić, Nenad
AU  - Garić-Grulović, Radmila
AU  - Miletic, Sasa
AU  - Savcic, Gordan
AU  - Dordevic, Bojana
PY  - 2010
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/5593
AB  - Industrial liquid wastes can be in the form of solutions, suspensions, sludges, scums or waste oil and have organic properties. The objective of this work was to demonstrate the technical feasibility of a fluidized bed as a clean technology for burning liquid waste from a pesticide production plant. The combustion of liquid waste mixtures, obtained from realistic samples, was investigated in a pilot scale fluidized bed with quartz sand particles of 0.63-1.25 mm in diameter and 2610 kg/m3 in density at 800-950°C. To ensure complete combustion of liquid waste and additional fuel, the combustion chamber was supplied with excess air and the U/UmF (at ambient temperature) was in between 1.1 and 2.3. In the fluidized bed chamber, liquid waste, additional liquid fuel and air can be brought into intense contact sufficient to permit combustion in bed without backfire problems. The experimental results show that the fluidized bed furnace offers excellent thermal uniformity and temperature control. The results of the combustion tests showed that degradation of liquid wastes can be successfully realized in a fluidized bed with no harmful gaseous emissions by ensuring that the temperatures of both the bed and the freeboard are not lower than 900°C.
AB  - Industrijski tečni otpad može biti u obliku rastvora, suspenzija, mulja, pene, otpadnog ulja i generalno sadrži različite organske komponente. Predmet ovog rada je demonstracija tretmana tečnog otpada sa visokim sadržajem zagađujućih materija fabrike za proizvodnju pesticida metodom termičke destrukcije u fluidizovanom sloju peska kao tehnički praktične i optimalne tehnologije. Ispitivanja sagorevanja realnih tečnih otpadnih smeša fabrike pesticida su izvršena u poluindustrijskom-demonstracionom postrojenju, tj. u fluidizacionoj koloni sa slojem kvarcnog peska granulacije 0,63-1,25 mm i gustine 2610 kg/m3 na 800-950°C. U cilju obezbeđenja potpunog sagorevanja tečnog otpada, u fluidizacionu kolonu je uvođen vazduh u višku i odnos U/UmF (na temperaturi okoline) je iznosio između 1,1 i 2,3. U fluidizacionoj koloni se tečni otpad, dodatno tečno gorivo i vazduh mogu dovesti u stanje intenzivnog kontakta što omogućava stabilno i homogeno sagorevanje u sloju. Rezultati eksperimentalnih ispitivanja pokazuju da se u fluidizovanom sloju peska ostvaruje veoma dobra termička uniformnost i kontrola temperatura. Rezultati ispitivanja sagorevanja su pokazali da se tečni otpad sa visokim sadržajem zagađujućih materija može uspešno termički tretirati u fluidizovanom sloju peska bez emisije štetnih produkata sagorevanja, pod uslovom da su u sloju i iznad sloja obezbeđene temperature iznad 900°C.
PB  - Serbian Chemical Society
T2  - Journal of the Serbian Chemical Society
T1  - Fluidized bed combustion of pesticide-manufacture liquid wastes
T1  - Sagorevanje tečnog otpada fabrike pesticida u fluidizovanom sloju
EP  - 535
IS  - 4
SP  - 523
VL  - 75
DO  - 10.2298/JSC090820024A
ER  - 

@article{
author = "Arsenijević, Zorana and Grbavčić, Željko and Grbić, Boško and Radić, Nenad and Garić-Grulović, Radmila and Miletic, Sasa and Savcic, Gordan and Dordevic, Bojana",
year = "2010",
abstract = "Industrial liquid wastes can be in the form of solutions, suspensions, sludges, scums or waste oil and have organic properties. The objective of this work was to demonstrate the technical feasibility of a fluidized bed as a clean technology for burning liquid waste from a pesticide production plant. The combustion of liquid waste mixtures, obtained from realistic samples, was investigated in a pilot scale fluidized bed with quartz sand particles of 0.63-1.25 mm in diameter and 2610 kg/m3 in density at 800-950°C. To ensure complete combustion of liquid waste and additional fuel, the combustion chamber was supplied with excess air and the U/UmF (at ambient temperature) was in between 1.1 and 2.3. In the fluidized bed chamber, liquid waste, additional liquid fuel and air can be brought into intense contact sufficient to permit combustion in bed without backfire problems. The experimental results show that the fluidized bed furnace offers excellent thermal uniformity and temperature control. The results of the combustion tests showed that degradation of liquid wastes can be successfully realized in a fluidized bed with no harmful gaseous emissions by ensuring that the temperatures of both the bed and the freeboard are not lower than 900°C., Industrijski tečni otpad može biti u obliku rastvora, suspenzija, mulja, pene, otpadnog ulja i generalno sadrži različite organske komponente. Predmet ovog rada je demonstracija tretmana tečnog otpada sa visokim sadržajem zagađujućih materija fabrike za proizvodnju pesticida metodom termičke destrukcije u fluidizovanom sloju peska kao tehnički praktične i optimalne tehnologije. Ispitivanja sagorevanja realnih tečnih otpadnih smeša fabrike pesticida su izvršena u poluindustrijskom-demonstracionom postrojenju, tj. u fluidizacionoj koloni sa slojem kvarcnog peska granulacije 0,63-1,25 mm i gustine 2610 kg/m3 na 800-950°C. U cilju obezbeđenja potpunog sagorevanja tečnog otpada, u fluidizacionu kolonu je uvođen vazduh u višku i odnos U/UmF (na temperaturi okoline) je iznosio između 1,1 i 2,3. U fluidizacionoj koloni se tečni otpad, dodatno tečno gorivo i vazduh mogu dovesti u stanje intenzivnog kontakta što omogućava stabilno i homogeno sagorevanje u sloju. Rezultati eksperimentalnih ispitivanja pokazuju da se u fluidizovanom sloju peska ostvaruje veoma dobra termička uniformnost i kontrola temperatura. Rezultati ispitivanja sagorevanja su pokazali da se tečni otpad sa visokim sadržajem zagađujućih materija može uspešno termički tretirati u fluidizovanom sloju peska bez emisije štetnih produkata sagorevanja, pod uslovom da su u sloju i iznad sloja obezbeđene temperature iznad 900°C.",
publisher = "Serbian Chemical Society",
journal = "Journal of the Serbian Chemical Society",
title = "Fluidized bed combustion of pesticide-manufacture liquid wastes, Sagorevanje tečnog otpada fabrike pesticida u fluidizovanom sloju",
pages = "535-523",
number = "4",
volume = "75",
doi = "10.2298/JSC090820024A"
}

Arsenijević, Z., Grbavčić, Ž., Grbić, B., Radić, N., Garić-Grulović, R., Miletic, S., Savcic, G.,& Dordevic, B.. (2010). Fluidized bed combustion of pesticide-manufacture liquid wastes. in Journal of the Serbian Chemical Society
Serbian Chemical Society., 75(4), 523-535.
https://doi.org/10.2298/JSC090820024A

Arsenijević Z, Grbavčić Ž, Grbić B, Radić N, Garić-Grulović R, Miletic S, Savcic G, Dordevic B. Fluidized bed combustion of pesticide-manufacture liquid wastes. in Journal of the Serbian Chemical Society. 2010;75(4):523-535.
doi:10.2298/JSC090820024A .

Arsenijević, Zorana, Grbavčić, Željko, Grbić, Boško, Radić, Nenad, Garić-Grulović, Radmila, Miletic, Sasa, Savcic, Gordan, Dordevic, Bojana, "Fluidized bed combustion of pesticide-manufacture liquid wastes" in Journal of the Serbian Chemical Society, 75, no. 4 (2010):523-535,
https://doi.org/10.2298/JSC090820024A . .

TY  - JOUR
AU  - Brzić, Danica
AU  - Schubert, M.
AU  - Haering, H.
AU  - Lange, R.
AU  - Petkovska, Menka
PY  - 2010
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1613
AB  - In this paper, we propose a new procedure for fast evaluation of the potential of periodic operations in trickle-bed reactors, based on empirical modeling. Step response experiments, with different input amplitudes, were performed on a laboratory trickle-bed reactor, in order to derive a simple nonlinear dynamic model. a-methylstyrene (AMS) hydrogenation was used as a test reaction and the feed AMS concentration was used as the modulated input. An empirical nonlinear model was postulated and used for simulation of periodic operations. The simulation of a periodic operation with sinusoidal modulation of the inlet AMS concentration with 40 % amplitude resulted up to 35% higher time-averaged conversion than the corresponding steady-state one.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Chemical Engineering Science
T1  - Evaluation of periodic operation of a trickle-bed reactor based on empirical modeling
EP  - 4165
IS  - 14
SP  - 4160
VL  - 65
DO  - 10.1016/j.ces.2010.04.032
ER  - 

@article{
author = "Brzić, Danica and Schubert, M. and Haering, H. and Lange, R. and Petkovska, Menka",
year = "2010",
abstract = "In this paper, we propose a new procedure for fast evaluation of the potential of periodic operations in trickle-bed reactors, based on empirical modeling. Step response experiments, with different input amplitudes, were performed on a laboratory trickle-bed reactor, in order to derive a simple nonlinear dynamic model. a-methylstyrene (AMS) hydrogenation was used as a test reaction and the feed AMS concentration was used as the modulated input. An empirical nonlinear model was postulated and used for simulation of periodic operations. The simulation of a periodic operation with sinusoidal modulation of the inlet AMS concentration with 40 % amplitude resulted up to 35% higher time-averaged conversion than the corresponding steady-state one.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Chemical Engineering Science",
title = "Evaluation of periodic operation of a trickle-bed reactor based on empirical modeling",
pages = "4165-4160",
number = "14",
volume = "65",
doi = "10.1016/j.ces.2010.04.032"
}

Brzić, D., Schubert, M., Haering, H., Lange, R.,& Petkovska, M.. (2010). Evaluation of periodic operation of a trickle-bed reactor based on empirical modeling. in Chemical Engineering Science
Pergamon-Elsevier Science Ltd, Oxford., 65(14), 4160-4165.
https://doi.org/10.1016/j.ces.2010.04.032

Brzić D, Schubert M, Haering H, Lange R, Petkovska M. Evaluation of periodic operation of a trickle-bed reactor based on empirical modeling. in Chemical Engineering Science. 2010;65(14):4160-4165.
doi:10.1016/j.ces.2010.04.032 .

Brzić, Danica, Schubert, M., Haering, H., Lange, R., Petkovska, Menka, "Evaluation of periodic operation of a trickle-bed reactor based on empirical modeling" in Chemical Engineering Science, 65, no. 14 (2010):4160-4165,
https://doi.org/10.1016/j.ces.2010.04.032 . .

TY  - JOUR
AU  - Bensmann, Boris
AU  - Petkovska, Menka
AU  - Vidaković-Koch, Tanja
AU  - Hanke-Rauschenbach, Richard
AU  - Sundmacher, Kai
PY  - 2010
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1652
AB  - In this theoretical contribution, nonlinear frequency response analysis was applied for the investigation of electrochemical methanol oxidation. This technique expresses the input-output behavior of any weakly nonlinear system with the help of the Volterra series expansion and generalized Fourier transform into so-called higher order frequency response functions. These functions contain the system's nonlinear fingerprint. They can be derived analytically from a nonlinear model. These functions can be obtained experimentally from the measurement of higher harmonics induced by a high amplitude sinusoidal perturbation of the system of interest. Frequency response functions up to the second order have been derived analytically for four different model varieties describing the kinetics of the electrochemical methanol oxidation. The first-order frequency response function corresponds to the reciprocal value of the well-known electrochemical impedance, which represents the linear part of the frequency response. This function does not contain sufficient information for discrimination between the different kinetic models. In contrast, the symmetrical second-order frequency response functions H(2)(omega,omega) show differences in shape, which substantiate the availability of the theoretical prerequisites for model discrimination. A detailed parametric study for all four model variants has been performed. The results show that the basic features of the shapes of the H(2)(omega,omega) amplitude spectra corresponding to the four models remain unique. The ubiquitousness of the qualitative differences between the competing models, for the whole set of parameters chosen for our analysis, suggests that the aforementioned amplitude spectra contain sufficient information for an unequivocal model discrimination.
PB  - Electrochemical Soc Inc, Pennington
T2  - Journal of the Electrochemical Society
T1  - Nonlinear Frequency Response of Electrochemical Methanol Oxidation Kinetics: A Theoretical Analysis
EP  - B1289
IS  - 9
SP  - B1279
VL  - 157
DO  - 10.1149/1.3446836
ER  - 

@article{
author = "Bensmann, Boris and Petkovska, Menka and Vidaković-Koch, Tanja and Hanke-Rauschenbach, Richard and Sundmacher, Kai",
year = "2010",
abstract = "In this theoretical contribution, nonlinear frequency response analysis was applied for the investigation of electrochemical methanol oxidation. This technique expresses the input-output behavior of any weakly nonlinear system with the help of the Volterra series expansion and generalized Fourier transform into so-called higher order frequency response functions. These functions contain the system's nonlinear fingerprint. They can be derived analytically from a nonlinear model. These functions can be obtained experimentally from the measurement of higher harmonics induced by a high amplitude sinusoidal perturbation of the system of interest. Frequency response functions up to the second order have been derived analytically for four different model varieties describing the kinetics of the electrochemical methanol oxidation. The first-order frequency response function corresponds to the reciprocal value of the well-known electrochemical impedance, which represents the linear part of the frequency response. This function does not contain sufficient information for discrimination between the different kinetic models. In contrast, the symmetrical second-order frequency response functions H(2)(omega,omega) show differences in shape, which substantiate the availability of the theoretical prerequisites for model discrimination. A detailed parametric study for all four model variants has been performed. The results show that the basic features of the shapes of the H(2)(omega,omega) amplitude spectra corresponding to the four models remain unique. The ubiquitousness of the qualitative differences between the competing models, for the whole set of parameters chosen for our analysis, suggests that the aforementioned amplitude spectra contain sufficient information for an unequivocal model discrimination.",
publisher = "Electrochemical Soc Inc, Pennington",
journal = "Journal of the Electrochemical Society",
title = "Nonlinear Frequency Response of Electrochemical Methanol Oxidation Kinetics: A Theoretical Analysis",
pages = "B1289-B1279",
number = "9",
volume = "157",
doi = "10.1149/1.3446836"
}

Bensmann, B., Petkovska, M., Vidaković-Koch, T., Hanke-Rauschenbach, R.,& Sundmacher, K.. (2010). Nonlinear Frequency Response of Electrochemical Methanol Oxidation Kinetics: A Theoretical Analysis. in Journal of the Electrochemical Society
Electrochemical Soc Inc, Pennington., 157(9), B1279-B1289.
https://doi.org/10.1149/1.3446836

Bensmann B, Petkovska M, Vidaković-Koch T, Hanke-Rauschenbach R, Sundmacher K. Nonlinear Frequency Response of Electrochemical Methanol Oxidation Kinetics: A Theoretical Analysis. in Journal of the Electrochemical Society. 2010;157(9):B1279-B1289.
doi:10.1149/1.3446836 .

Bensmann, Boris, Petkovska, Menka, Vidaković-Koch, Tanja, Hanke-Rauschenbach, Richard, Sundmacher, Kai, "Nonlinear Frequency Response of Electrochemical Methanol Oxidation Kinetics: A Theoretical Analysis" in Journal of the Electrochemical Society, 157, no. 9 (2010):B1279-B1289,
https://doi.org/10.1149/1.3446836 . .

TY  - JOUR
AU  - Kaluđerović-Radoičić, Tatjana
AU  - Raičević, Slavica
PY  - 2010
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1619
AB  - Natural apatites represent a cost effective soil amendment, which can be used for in situ reduction of lead bioavailability and mobility. In our previous work, we selected Lisina apatite (LA) as a promising natural mineral for lead immobilization based on theoretical predictions. This study investigated the adsorption equilibrium and kinetics of aqueous Pb sorption onto Lisina apatite and synthetic hydroxyapatite (HAP) at different temperatures. XRD analysis indicated that LA consists of three minerals: fluorapatite, quartz and muscovite. After reaction with a Pb solution, only FA peaks were changed, confirming that fluorapatite present in LA is responsible for Pb sorption. Sorption experiments confirmed that both LA and HAP are effective in Pb removal. Langmuir, Freundlich, Temkin, Koble-Corrigan and Redlich-Peterson isotherm models were applied to experimental data. The kinetics of the sorption process on both minerals was well characterized by the pseudo-second order reaction rate. Results indicate that Pb immobilization by HAP is a two-step process: the first rapid phase, possibly surface complexation and secondary dissolution of HAP and precipitation of pyromorphite. The sorption of Pb by Lisina apatite is also a two-step process, but the reaction mechanisms are more complicated and need further research as the results indicate that different mechanisms dominate at different temperatures. The values of thermodynamic equilibrium constants and Gibbs free energy were also calculated. The values of AG obtained confirm the feasibility of both HAP and LA as effective sorbents of the Pb ion.
PB  - Elsevier Science Sa, Lausanne
T2  - Chemical Engineering Journal
T1  - Aqueous Pb sorption by synthetic and natural apatite: Kinetics, equilibrium and thermodynamic studies
EP  - 510
IS  - 2
SP  - 503
VL  - 160
DO  - 10.1016/j.cej.2010.03.061
ER  - 

@article{
author = "Kaluđerović-Radoičić, Tatjana and Raičević, Slavica",
year = "2010",
abstract = "Natural apatites represent a cost effective soil amendment, which can be used for in situ reduction of lead bioavailability and mobility. In our previous work, we selected Lisina apatite (LA) as a promising natural mineral for lead immobilization based on theoretical predictions. This study investigated the adsorption equilibrium and kinetics of aqueous Pb sorption onto Lisina apatite and synthetic hydroxyapatite (HAP) at different temperatures. XRD analysis indicated that LA consists of three minerals: fluorapatite, quartz and muscovite. After reaction with a Pb solution, only FA peaks were changed, confirming that fluorapatite present in LA is responsible for Pb sorption. Sorption experiments confirmed that both LA and HAP are effective in Pb removal. Langmuir, Freundlich, Temkin, Koble-Corrigan and Redlich-Peterson isotherm models were applied to experimental data. The kinetics of the sorption process on both minerals was well characterized by the pseudo-second order reaction rate. Results indicate that Pb immobilization by HAP is a two-step process: the first rapid phase, possibly surface complexation and secondary dissolution of HAP and precipitation of pyromorphite. The sorption of Pb by Lisina apatite is also a two-step process, but the reaction mechanisms are more complicated and need further research as the results indicate that different mechanisms dominate at different temperatures. The values of thermodynamic equilibrium constants and Gibbs free energy were also calculated. The values of AG obtained confirm the feasibility of both HAP and LA as effective sorbents of the Pb ion.",
publisher = "Elsevier Science Sa, Lausanne",
journal = "Chemical Engineering Journal",
title = "Aqueous Pb sorption by synthetic and natural apatite: Kinetics, equilibrium and thermodynamic studies",
pages = "510-503",
number = "2",
volume = "160",
doi = "10.1016/j.cej.2010.03.061"
}

Kaluđerović-Radoičić, T.,& Raičević, S.. (2010). Aqueous Pb sorption by synthetic and natural apatite: Kinetics, equilibrium and thermodynamic studies. in Chemical Engineering Journal
Elsevier Science Sa, Lausanne., 160(2), 503-510.
https://doi.org/10.1016/j.cej.2010.03.061

Kaluđerović-Radoičić T, Raičević S. Aqueous Pb sorption by synthetic and natural apatite: Kinetics, equilibrium and thermodynamic studies. in Chemical Engineering Journal. 2010;160(2):503-510.
doi:10.1016/j.cej.2010.03.061 .

Kaluđerović-Radoičić, Tatjana, Raičević, Slavica, "Aqueous Pb sorption by synthetic and natural apatite: Kinetics, equilibrium and thermodynamic studies" in Chemical Engineering Journal, 160, no. 2 (2010):503-510,
https://doi.org/10.1016/j.cej.2010.03.061 . .

TY  - JOUR
AU  - Petkovska, Menka
AU  - Nikolić, Daliborka
AU  - Marković, Ana
AU  - Seidel-Morgenstern, Andreas
PY  - 2010
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1612
AB  - The concept of higher-order frequency response functions (FRFs), which is based on Volterra series representation of nonlineral systems, is used to analyse the time-average performance of a perfectly mixed reactor subject to periodic modulation of the inlet concentration, for a simple n-th order heterogeneous catalytic reaction. The second order frequency response function G(2)(omega, omega), which corresponds to the dominant term of the non-periodic (DC) component, essentially determines the average performance of the periodic process. Thus, in order to evaluate the potential of a periodic operation, it is sufficient to derive and analyse the G(2)(omega, omega) function. The sign of this function defines the sign of the DC component and reveals whether the periodic operation is favourable compared to conventional steady state operation, or not. It will be shown that, for the case investigated, the sign of this function depends both on the reaction order and on the shape of the adsorption isotherm.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Chemical Engineering Science
T1  - Fast evaluation of periodic operation of a heterogeneous reactor based on nonlinear frequency response analysis
EP  - 3637
IS  - 11
SP  - 3632
VL  - 65
DO  - 10.1016/j.ces.2010.03.011
ER  - 

@article{
author = "Petkovska, Menka and Nikolić, Daliborka and Marković, Ana and Seidel-Morgenstern, Andreas",
year = "2010",
abstract = "The concept of higher-order frequency response functions (FRFs), which is based on Volterra series representation of nonlineral systems, is used to analyse the time-average performance of a perfectly mixed reactor subject to periodic modulation of the inlet concentration, for a simple n-th order heterogeneous catalytic reaction. The second order frequency response function G(2)(omega, omega), which corresponds to the dominant term of the non-periodic (DC) component, essentially determines the average performance of the periodic process. Thus, in order to evaluate the potential of a periodic operation, it is sufficient to derive and analyse the G(2)(omega, omega) function. The sign of this function defines the sign of the DC component and reveals whether the periodic operation is favourable compared to conventional steady state operation, or not. It will be shown that, for the case investigated, the sign of this function depends both on the reaction order and on the shape of the adsorption isotherm.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Chemical Engineering Science",
title = "Fast evaluation of periodic operation of a heterogeneous reactor based on nonlinear frequency response analysis",
pages = "3637-3632",
number = "11",
volume = "65",
doi = "10.1016/j.ces.2010.03.011"
}

Petkovska, M., Nikolić, D., Marković, A.,& Seidel-Morgenstern, A.. (2010). Fast evaluation of periodic operation of a heterogeneous reactor based on nonlinear frequency response analysis. in Chemical Engineering Science
Pergamon-Elsevier Science Ltd, Oxford., 65(11), 3632-3637.
https://doi.org/10.1016/j.ces.2010.03.011

Petkovska M, Nikolić D, Marković A, Seidel-Morgenstern A. Fast evaluation of periodic operation of a heterogeneous reactor based on nonlinear frequency response analysis. in Chemical Engineering Science. 2010;65(11):3632-3637.
doi:10.1016/j.ces.2010.03.011 .

Petkovska, Menka, Nikolić, Daliborka, Marković, Ana, Seidel-Morgenstern, Andreas, "Fast evaluation of periodic operation of a heterogeneous reactor based on nonlinear frequency response analysis" in Chemical Engineering Science, 65, no. 11 (2010):3632-3637,
https://doi.org/10.1016/j.ces.2010.03.011 . .

TY  - JOUR
AU  - Nikačević, Nikola
AU  - Predojević, Zlatica J.
AU  - Petrović, Dragan Lj.
AU  - Duduković, Aleksandar
PY  - 2009
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1503
AB  - Static holdup was investigated experimentally and theoretically in gas - flowing solids - fixed bed bench-scale contactors. Diverse packing elements were used: Raschig rings, ceramic beads, crushed stone and glass beads. Four different flowing solids particles were examined: sand. propant, alumina and glass. A wide range of solid fluxes and gas velocities were used in this study. The experimental results showed a significant influence of the geometry of the packing elements oil static holdup. The physical properties of the flowing solids also influenced static holdup. A moderate influence of solids flux and a minor influence of gas velocity were observed. An empirical correlation for the prediction of static holdup was developed from theoretical and numerical analyses, based on the available experimental data. This simple equation well predicts static holdup and it contains one parameter that has to be measured in the desirable system - dynamic holdup. Alternatively. dynamic holdup can be predicted by previously proposed models. One of those models was integrated into the proposed correlation for static holdup, which gave quite good results.
PB  - Elsevier Science Bv, Amsterdam
T2  - Powder Technology
T1  - Static holdup in Gas - Flowing solids - Fixed bed contactors
EP  - 129
IS  - 1-2
SP  - 122
VL  - 191
DO  - 10.1016/j.powtec.2008.09.011
ER  - 

@article{
author = "Nikačević, Nikola and Predojević, Zlatica J. and Petrović, Dragan Lj. and Duduković, Aleksandar",
year = "2009",
abstract = "Static holdup was investigated experimentally and theoretically in gas - flowing solids - fixed bed bench-scale contactors. Diverse packing elements were used: Raschig rings, ceramic beads, crushed stone and glass beads. Four different flowing solids particles were examined: sand. propant, alumina and glass. A wide range of solid fluxes and gas velocities were used in this study. The experimental results showed a significant influence of the geometry of the packing elements oil static holdup. The physical properties of the flowing solids also influenced static holdup. A moderate influence of solids flux and a minor influence of gas velocity were observed. An empirical correlation for the prediction of static holdup was developed from theoretical and numerical analyses, based on the available experimental data. This simple equation well predicts static holdup and it contains one parameter that has to be measured in the desirable system - dynamic holdup. Alternatively. dynamic holdup can be predicted by previously proposed models. One of those models was integrated into the proposed correlation for static holdup, which gave quite good results.",
publisher = "Elsevier Science Bv, Amsterdam",
journal = "Powder Technology",
title = "Static holdup in Gas - Flowing solids - Fixed bed contactors",
pages = "129-122",
number = "1-2",
volume = "191",
doi = "10.1016/j.powtec.2008.09.011"
}

Nikačević, N., Predojević, Z. J., Petrović, D. Lj.,& Duduković, A.. (2009). Static holdup in Gas - Flowing solids - Fixed bed contactors. in Powder Technology
Elsevier Science Bv, Amsterdam., 191(1-2), 122-129.
https://doi.org/10.1016/j.powtec.2008.09.011

Nikačević N, Predojević ZJ, Petrović DL, Duduković A. Static holdup in Gas - Flowing solids - Fixed bed contactors. in Powder Technology. 2009;191(1-2):122-129.
doi:10.1016/j.powtec.2008.09.011 .

Nikačević, Nikola, Predojević, Zlatica J., Petrović, Dragan Lj., Duduković, Aleksandar, "Static holdup in Gas - Flowing solids - Fixed bed contactors" in Powder Technology, 191, no. 1-2 (2009):122-129,
https://doi.org/10.1016/j.powtec.2008.09.011 . .

TY  - JOUR
AU  - Nikačević, Nikola
AU  - Petkovska, Menka
AU  - Duduković, Milorad P.
PY  - 2009
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1516
AB  - An experimental investigation of the solids flow pattern in gas-flowing solids-fixed bed contactors is presented. The apparatus and procedures for determining the dynamic and static solids holdups, solids residence time distribution and the extent and rate of the exchange between particles in the static and dynamic solids holdup are described in detail. Experiments were performed in a bench scale system, containing a column (diameter similar to 60 mm) packed with glass beads of 16 mm in diameter packed up to the height of 0.8 m. Tracer experiments with a step input in flowing solids phase were used for determining the residence time distribution and exchange between particles. Fine solids (spheres with mean diameter of 291 pm) of two different colors (all other properties being the same) were used in the tracer experiments to determine the residence time distribution and the exchange between static and dynamic solids holdup. In both types of experiments, the response curves have been obtained via color analysis of digital photos. All experiments have been repeated at different operating conditions, with a broad variation of solids mass flux and gas velocity, and reproducibility at set conditions was checked. The obtained experimental results are discussed and the observed important characteristics of the solids flow pattern are outlined. The effects of the solids flux and gas velocity on the solids flow pattern are presented and analyzed.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Chemical Engineering Science
T1  - Solids flow pattern in gas-flowing solids-fixed bed contactors. Part I Experimental
EP  - 2509
IS  - 10
SP  - 2501
VL  - 64
DO  - 10.1016/j.ces.2009.02.029
ER  - 

@article{
author = "Nikačević, Nikola and Petkovska, Menka and Duduković, Milorad P.",
year = "2009",
abstract = "An experimental investigation of the solids flow pattern in gas-flowing solids-fixed bed contactors is presented. The apparatus and procedures for determining the dynamic and static solids holdups, solids residence time distribution and the extent and rate of the exchange between particles in the static and dynamic solids holdup are described in detail. Experiments were performed in a bench scale system, containing a column (diameter similar to 60 mm) packed with glass beads of 16 mm in diameter packed up to the height of 0.8 m. Tracer experiments with a step input in flowing solids phase were used for determining the residence time distribution and exchange between particles. Fine solids (spheres with mean diameter of 291 pm) of two different colors (all other properties being the same) were used in the tracer experiments to determine the residence time distribution and the exchange between static and dynamic solids holdup. In both types of experiments, the response curves have been obtained via color analysis of digital photos. All experiments have been repeated at different operating conditions, with a broad variation of solids mass flux and gas velocity, and reproducibility at set conditions was checked. The obtained experimental results are discussed and the observed important characteristics of the solids flow pattern are outlined. The effects of the solids flux and gas velocity on the solids flow pattern are presented and analyzed.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Chemical Engineering Science",
title = "Solids flow pattern in gas-flowing solids-fixed bed contactors. Part I Experimental",
pages = "2509-2501",
number = "10",
volume = "64",
doi = "10.1016/j.ces.2009.02.029"
}

Nikačević, N., Petkovska, M.,& Duduković, M. P.. (2009). Solids flow pattern in gas-flowing solids-fixed bed contactors. Part I Experimental. in Chemical Engineering Science
Pergamon-Elsevier Science Ltd, Oxford., 64(10), 2501-2509.
https://doi.org/10.1016/j.ces.2009.02.029

Nikačević N, Petkovska M, Duduković MP. Solids flow pattern in gas-flowing solids-fixed bed contactors. Part I Experimental. in Chemical Engineering Science. 2009;64(10):2501-2509.
doi:10.1016/j.ces.2009.02.029 .

Nikačević, Nikola, Petkovska, Menka, Duduković, Milorad P., "Solids flow pattern in gas-flowing solids-fixed bed contactors. Part I Experimental" in Chemical Engineering Science, 64, no. 10 (2009):2501-2509,
https://doi.org/10.1016/j.ces.2009.02.029 . .

TY  - JOUR
AU  - Nikačević, Nikola
AU  - Petkovska, Menka
AU  - Duduković, Milorad P.
PY  - 2009
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1517
AB  - In this paper a mathematical model for solids flow in gas-flowing solids-fixed bed contactors is developed. The presented four-parameter model assumes plug flow with axial dispersion in the dynamic, fast moving solids zone and the exchange of particles from this zone with the static zones. The complex dynamic behavior of the 'static' particles is described with a model of exchange between the dynamic and three static zones: (a) the 'fast' exchanging, (b) the 'slow' exchanging and
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Chemical Engineering Science
T1  - Solids flow pattern in gas-flowing solids-fixed bed contactors. Part II Mathematical modeling
EP  - 2500
IS  - 10
SP  - 2491
VL  - 64
DO  - 10.1016/j.ces.2009.02.028
ER  - 

@article{
author = "Nikačević, Nikola and Petkovska, Menka and Duduković, Milorad P.",
year = "2009",
abstract = "In this paper a mathematical model for solids flow in gas-flowing solids-fixed bed contactors is developed. The presented four-parameter model assumes plug flow with axial dispersion in the dynamic, fast moving solids zone and the exchange of particles from this zone with the static zones. The complex dynamic behavior of the 'static' particles is described with a model of exchange between the dynamic and three static zones: (a) the 'fast' exchanging, (b) the 'slow' exchanging and",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Chemical Engineering Science",
title = "Solids flow pattern in gas-flowing solids-fixed bed contactors. Part II Mathematical modeling",
pages = "2500-2491",
number = "10",
volume = "64",
doi = "10.1016/j.ces.2009.02.028"
}

Nikačević, N., Petkovska, M.,& Duduković, M. P.. (2009). Solids flow pattern in gas-flowing solids-fixed bed contactors. Part II Mathematical modeling. in Chemical Engineering Science
Pergamon-Elsevier Science Ltd, Oxford., 64(10), 2491-2500.
https://doi.org/10.1016/j.ces.2009.02.028

Nikačević N, Petkovska M, Duduković MP. Solids flow pattern in gas-flowing solids-fixed bed contactors. Part II Mathematical modeling. in Chemical Engineering Science. 2009;64(10):2491-2500.
doi:10.1016/j.ces.2009.02.028 .

Nikačević, Nikola, Petkovska, Menka, Duduković, Milorad P., "Solids flow pattern in gas-flowing solids-fixed bed contactors. Part II Mathematical modeling" in Chemical Engineering Science, 64, no. 10 (2009):2491-2500,
https://doi.org/10.1016/j.ces.2009.02.028 . .

TY  - JOUR
AU  - Grbić, Boško
AU  - Radić, Nenad
AU  - Arsenijević, Zorana
AU  - Garić-Grulović, Radmila
AU  - Grbavčić, Željko
PY  - 2009
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/5539
AB  - The deep oxidation of dimethylamine (DMA) was studied over Pt/Al2O3 catalysts with small (1 nm) and large (7.8-15.5 nm) Pt crystallite sizes. The turnover frequency (TOF) was higher for the large than for the small Pt crystallites, indicating that the reaction is structure sensitive. Two kinetic models were used to interpret the obtained results, i.e., the Mars van Krevelen and a mechanism based on the adsorption of oxygen and adsorption of dimethylamine on different active sites were employed. Both models showed that the activation energy for the oxygen chemisorption rate constant (k(o)) decreased with increasing of Pt crystallite size and that the activation energy for the surface reaction rate constant (k(i)) was independent of the Pt crystallite size. The structure sensitivity may be explained by differences in the reactivity of the oxygen adsorbed on these Pt crystallites. The Mars van Krevelen model fits the TOF values very well at concentrations of DMA higher than 1500 ppm, while in the lower concentrations region, the model under predicts the experimental data. The model based on the adsorption of oxygen and DMA on different active sites fits the experimental data quite well over the whole temperature and concentration range. The fitted values of the Henry adsorption constant are independent of the Pt crystallite size.
PB  - Elsevier
T2  - Applied Catalysis B-Environmental
T1  - Structure sensitivity of dimethylamine deep oxidation over Pt/Al2O3 catalysts
EP  - 484
IS  - 3-4
SP  - 478
VL  - 90
DO  - 10.1016/j.apcatb.2009.04.008
ER  - 

@article{
author = "Grbić, Boško and Radić, Nenad and Arsenijević, Zorana and Garić-Grulović, Radmila and Grbavčić, Željko",
year = "2009",
abstract = "The deep oxidation of dimethylamine (DMA) was studied over Pt/Al2O3 catalysts with small (1 nm) and large (7.8-15.5 nm) Pt crystallite sizes. The turnover frequency (TOF) was higher for the large than for the small Pt crystallites, indicating that the reaction is structure sensitive. Two kinetic models were used to interpret the obtained results, i.e., the Mars van Krevelen and a mechanism based on the adsorption of oxygen and adsorption of dimethylamine on different active sites were employed. Both models showed that the activation energy for the oxygen chemisorption rate constant (k(o)) decreased with increasing of Pt crystallite size and that the activation energy for the surface reaction rate constant (k(i)) was independent of the Pt crystallite size. The structure sensitivity may be explained by differences in the reactivity of the oxygen adsorbed on these Pt crystallites. The Mars van Krevelen model fits the TOF values very well at concentrations of DMA higher than 1500 ppm, while in the lower concentrations region, the model under predicts the experimental data. The model based on the adsorption of oxygen and DMA on different active sites fits the experimental data quite well over the whole temperature and concentration range. The fitted values of the Henry adsorption constant are independent of the Pt crystallite size.",
publisher = "Elsevier",
journal = "Applied Catalysis B-Environmental",
title = "Structure sensitivity of dimethylamine deep oxidation over Pt/Al2O3 catalysts",
pages = "484-478",
number = "3-4",
volume = "90",
doi = "10.1016/j.apcatb.2009.04.008"
}

Grbić, B., Radić, N., Arsenijević, Z., Garić-Grulović, R.,& Grbavčić, Ž.. (2009). Structure sensitivity of dimethylamine deep oxidation over Pt/Al2O3 catalysts. in Applied Catalysis B-Environmental
Elsevier., 90(3-4), 478-484.
https://doi.org/10.1016/j.apcatb.2009.04.008

Grbić B, Radić N, Arsenijević Z, Garić-Grulović R, Grbavčić Ž. Structure sensitivity of dimethylamine deep oxidation over Pt/Al2O3 catalysts. in Applied Catalysis B-Environmental. 2009;90(3-4):478-484.
doi:10.1016/j.apcatb.2009.04.008 .

Grbić, Boško, Radić, Nenad, Arsenijević, Zorana, Garić-Grulović, Radmila, Grbavčić, Željko, "Structure sensitivity of dimethylamine deep oxidation over Pt/Al2O3 catalysts" in Applied Catalysis B-Environmental, 90, no. 3-4 (2009):478-484,
https://doi.org/10.1016/j.apcatb.2009.04.008 . .

TY  - CONF
AU  - Petkovska, Menka
AU  - Nikolić, Daliborka
AU  - Marković, Ana
AU  - Seidel-Morgenstern, Andreas
PY  - 2009
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1368
AB  - One way to achieve process intensification is to operate the process in a periodic way, in order to obtain better average performance compared to the optimal steady-state operation. The source of the possible improvement lies in the process nonlinearity. Nevertheless, the improvement is obtained only in some cases, while in some others the periodic operation can be unfavourable. Testing whether a potential periodic process is favourable or unfavourable generally demands long and tedious experimental and/or numerical work. This paper presents a new, fast and easy method for this testing, based on the Volterra series approach, nonlinear frequency response and the concept of higher order frequency response functions.
C3  - 2nd European Process Intensification Conference (EPIC 2009), Venice, Italy
T1  - Frequency response analysis as a tool for fast evaluation of  periodic operations. Case study: A heterogeneous catalytic reacator
UR  - https://hdl.handle.net/21.15107/rcub_technorep_1368
ER  - 

@conference{
author = "Petkovska, Menka and Nikolić, Daliborka and Marković, Ana and Seidel-Morgenstern, Andreas",
year = "2009",
abstract = "One way to achieve process intensification is to operate the process in a periodic way, in order to obtain better average performance compared to the optimal steady-state operation. The source of the possible improvement lies in the process nonlinearity. Nevertheless, the improvement is obtained only in some cases, while in some others the periodic operation can be unfavourable. Testing whether a potential periodic process is favourable or unfavourable generally demands long and tedious experimental and/or numerical work. This paper presents a new, fast and easy method for this testing, based on the Volterra series approach, nonlinear frequency response and the concept of higher order frequency response functions.",
journal = "2nd European Process Intensification Conference (EPIC 2009), Venice, Italy",
title = "Frequency response analysis as a tool for fast evaluation of  periodic operations. Case study: A heterogeneous catalytic reacator",
url = "https://hdl.handle.net/21.15107/rcub_technorep_1368"
}

Petkovska, M., Nikolić, D., Marković, A.,& Seidel-Morgenstern, A.. (2009). Frequency response analysis as a tool for fast evaluation of  periodic operations. Case study: A heterogeneous catalytic reacator. in 2nd European Process Intensification Conference (EPIC 2009), Venice, Italy.
https://hdl.handle.net/21.15107/rcub_technorep_1368

Petkovska M, Nikolić D, Marković A, Seidel-Morgenstern A. Frequency response analysis as a tool for fast evaluation of  periodic operations. Case study: A heterogeneous catalytic reacator. in 2nd European Process Intensification Conference (EPIC 2009), Venice, Italy. 2009;.
https://hdl.handle.net/21.15107/rcub_technorep_1368 .

Petkovska, Menka, Nikolić, Daliborka, Marković, Ana, Seidel-Morgenstern, Andreas, "Frequency response analysis as a tool for fast evaluation of  periodic operations. Case study: A heterogeneous catalytic reacator" in 2nd European Process Intensification Conference (EPIC 2009), Venice, Italy (2009),
https://hdl.handle.net/21.15107/rcub_technorep_1368 .

TY  - JOUR
AU  - Petkovska, Menka
PY  - 2009
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1367
AB  - Two main directions of application of nonlinear frequency response and the concept of higher order frequency response functions (FRFs) in investigation of adsorption systems are presented, one for development of novel methods for investigation of equilibrium and kinetics of adsorption systems, and the other for fast estimation of periodic steady-states of cyclic adsorption processes. The main advantages of the nonlinear FR methods for estimation of adsorption equilibrium and kinetics are: (1) It is possible to discriminate between different kinetic mechanisms and to select the correct one from the shapes of the second and higher order FRFs. (2) Both equilibrium and kinetic parameters can be estimated from the FRFs. Different experimental arrangements are presented. Estimation of periodic steady-states of cyclic adsorption processes is illustrated on the example of periodic operation of an adsorption column with modulation of the inlet concentration and the column temperature.
PB  - Soc Chemists Technologists Madeconia, Skopje
T2  - Macedonian Journal of Chemistry and Chemical Engineering
T1  - Applications of non-linear frequency response for investigation of adsorption systems
EP  - 16
IS  - 1
SP  - 1
VL  - 28
DO  - 10.20450/mjcce.2009.217
ER  - 

@article{
author = "Petkovska, Menka",
year = "2009",
abstract = "Two main directions of application of nonlinear frequency response and the concept of higher order frequency response functions (FRFs) in investigation of adsorption systems are presented, one for development of novel methods for investigation of equilibrium and kinetics of adsorption systems, and the other for fast estimation of periodic steady-states of cyclic adsorption processes. The main advantages of the nonlinear FR methods for estimation of adsorption equilibrium and kinetics are: (1) It is possible to discriminate between different kinetic mechanisms and to select the correct one from the shapes of the second and higher order FRFs. (2) Both equilibrium and kinetic parameters can be estimated from the FRFs. Different experimental arrangements are presented. Estimation of periodic steady-states of cyclic adsorption processes is illustrated on the example of periodic operation of an adsorption column with modulation of the inlet concentration and the column temperature.",
publisher = "Soc Chemists Technologists Madeconia, Skopje",
journal = "Macedonian Journal of Chemistry and Chemical Engineering",
title = "Applications of non-linear frequency response for investigation of adsorption systems",
pages = "16-1",
number = "1",
volume = "28",
doi = "10.20450/mjcce.2009.217"
}

Petkovska, M.. (2009). Applications of non-linear frequency response for investigation of adsorption systems. in Macedonian Journal of Chemistry and Chemical Engineering
Soc Chemists Technologists Madeconia, Skopje., 28(1), 1-16.
https://doi.org/10.20450/mjcce.2009.217

Petkovska M. Applications of non-linear frequency response for investigation of adsorption systems. in Macedonian Journal of Chemistry and Chemical Engineering. 2009;28(1):1-16.
doi:10.20450/mjcce.2009.217 .

Petkovska, Menka, "Applications of non-linear frequency response for investigation of adsorption systems" in Macedonian Journal of Chemistry and Chemical Engineering, 28, no. 1 (2009):1-16,
https://doi.org/10.20450/mjcce.2009.217 . .

TY  - JOUR
AU  - Arsenijević, Zorana
AU  - Grbić, Boško
AU  - Grbavčić, Željko
AU  - Miletić, Saša
AU  - Savčić, Gordan
AU  - Radić, Nenad
AU  - Garić-Grulović, Radmila
PY  - 2008
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/5577
AB  - The widely used herbicide, dimethylamine salt of 2,4-dichlorophenoxy acetic acid (2,4-D-DMA), is usually prepared by mixing a dimethylamine (DMA) aqueous solution with a solid 2,4-dichlorophenoxy acetic acid (2,4-D). The vapors of the both, reactants and products, are potentially hazardous for the environment. The contribution of DMA vapors in overall pollution from this process is most significant, concerning vapor pressures data of these pollutants. Therefore, the control of the air pollution in the manufacture and handling of methylamines is very important. Within this paper, the optimal air pollution control system in preparation of 2,4-D-DMA was developed for the pesticides manufacturing industry. This study employed the simple pollution prevention concept to reduce the emission of DMA vapors at the source. The investigations were performed on the pilot plant scale. To reduce the emission of DMA vapors, the effluent gases from the herbicide preparation zone were passed through the packed bed scrubber (water scrubbing medium), and the catalytic reactor in sequence. The end result is a substantially improved air quality in the working area, as well as in the urbanized areas located near the chemical plant.
PB  - Association of the Chemical Engineers of Serbia
T2  - Chemical Industry and Chemical Engineering Quarterly / CICEQ
T1  - Prevention and control of dimethylamine vapors emission: Herbicide production plant
EP  - 243
IS  - 4
SP  - 239
VL  - 14
DO  - 10.2298/CICEQ0804239A
ER  - 

@article{
author = "Arsenijević, Zorana and Grbić, Boško and Grbavčić, Željko and Miletić, Saša and Savčić, Gordan and Radić, Nenad and Garić-Grulović, Radmila",
year = "2008",
abstract = "The widely used herbicide, dimethylamine salt of 2,4-dichlorophenoxy acetic acid (2,4-D-DMA), is usually prepared by mixing a dimethylamine (DMA) aqueous solution with a solid 2,4-dichlorophenoxy acetic acid (2,4-D). The vapors of the both, reactants and products, are potentially hazardous for the environment. The contribution of DMA vapors in overall pollution from this process is most significant, concerning vapor pressures data of these pollutants. Therefore, the control of the air pollution in the manufacture and handling of methylamines is very important. Within this paper, the optimal air pollution control system in preparation of 2,4-D-DMA was developed for the pesticides manufacturing industry. This study employed the simple pollution prevention concept to reduce the emission of DMA vapors at the source. The investigations were performed on the pilot plant scale. To reduce the emission of DMA vapors, the effluent gases from the herbicide preparation zone were passed through the packed bed scrubber (water scrubbing medium), and the catalytic reactor in sequence. The end result is a substantially improved air quality in the working area, as well as in the urbanized areas located near the chemical plant.",
publisher = "Association of the Chemical Engineers of Serbia",
journal = "Chemical Industry and Chemical Engineering Quarterly / CICEQ",
title = "Prevention and control of dimethylamine vapors emission: Herbicide production plant",
pages = "243-239",
number = "4",
volume = "14",
doi = "10.2298/CICEQ0804239A"
}

Arsenijević, Z., Grbić, B., Grbavčić, Ž., Miletić, S., Savčić, G., Radić, N.,& Garić-Grulović, R.. (2008). Prevention and control of dimethylamine vapors emission: Herbicide production plant. in Chemical Industry and Chemical Engineering Quarterly / CICEQ
Association of the Chemical Engineers of Serbia., 14(4), 239-243.
https://doi.org/10.2298/CICEQ0804239A

Arsenijević Z, Grbić B, Grbavčić Ž, Miletić S, Savčić G, Radić N, Garić-Grulović R. Prevention and control of dimethylamine vapors emission: Herbicide production plant. in Chemical Industry and Chemical Engineering Quarterly / CICEQ. 2008;14(4):239-243.
doi:10.2298/CICEQ0804239A .

Arsenijević, Zorana, Grbić, Boško, Grbavčić, Željko, Miletić, Saša, Savčić, Gordan, Radić, Nenad, Garić-Grulović, Radmila, "Prevention and control of dimethylamine vapors emission: Herbicide production plant" in Chemical Industry and Chemical Engineering Quarterly / CICEQ, 14, no. 4 (2008):239-243,
https://doi.org/10.2298/CICEQ0804239A . .

TY  - JOUR
AU  - Petkovska, Menka
PY  - 2008
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1310
AB  - A new method for investigation of adsorption equilibrium and kinetics, named Nonlinear Frequency Response-Zero Length Column (NFR-ZLC) method, is introduced. It combines the advantages of the Nonlinear FR method (the potential to identify a model corresponding to the most probable kinetic mechanism and to estimate the equilibrium and kinetic parameters of the identified model) and of the ZLC method (the potential to derive direct information about the processes on the particle level, by eliminating the influence of the adsorber). The frequency response functions of a ZLC system, up to the third order, and for three simple kinetic mechanisms (film resistance control, micropore diffusion control and pore-surface diffusion control) are derived and simulated. The procedure for estimation of the equilibrium and kinetic parameters is defined and illustrated based on numerical simulations.
PB  - Springer, New York
T2  - Adsorption-Journal of the International Adsorption Society
T1  - Nonlinear FR-ZLC method for investigation of adsorption equilibrium and kinetics
EP  - 239
IS  - 2-3
SP  - 223
VL  - 14
DO  - 10.1007/s10450-007-9079-4
ER  - 

@article{
author = "Petkovska, Menka",
year = "2008",
abstract = "A new method for investigation of adsorption equilibrium and kinetics, named Nonlinear Frequency Response-Zero Length Column (NFR-ZLC) method, is introduced. It combines the advantages of the Nonlinear FR method (the potential to identify a model corresponding to the most probable kinetic mechanism and to estimate the equilibrium and kinetic parameters of the identified model) and of the ZLC method (the potential to derive direct information about the processes on the particle level, by eliminating the influence of the adsorber). The frequency response functions of a ZLC system, up to the third order, and for three simple kinetic mechanisms (film resistance control, micropore diffusion control and pore-surface diffusion control) are derived and simulated. The procedure for estimation of the equilibrium and kinetic parameters is defined and illustrated based on numerical simulations.",
publisher = "Springer, New York",
journal = "Adsorption-Journal of the International Adsorption Society",
title = "Nonlinear FR-ZLC method for investigation of adsorption equilibrium and kinetics",
pages = "239-223",
number = "2-3",
volume = "14",
doi = "10.1007/s10450-007-9079-4"
}

Petkovska, M.. (2008). Nonlinear FR-ZLC method for investigation of adsorption equilibrium and kinetics. in Adsorption-Journal of the International Adsorption Society
Springer, New York., 14(2-3), 223-239.
https://doi.org/10.1007/s10450-007-9079-4

Petkovska M. Nonlinear FR-ZLC method for investigation of adsorption equilibrium and kinetics. in Adsorption-Journal of the International Adsorption Society. 2008;14(2-3):223-239.
doi:10.1007/s10450-007-9079-4 .

Petkovska, Menka, "Nonlinear FR-ZLC method for investigation of adsorption equilibrium and kinetics" in Adsorption-Journal of the International Adsorption Society, 14, no. 2-3 (2008):223-239,
https://doi.org/10.1007/s10450-007-9079-4 . .

TY  - JOUR
AU  - Nikačević, Nikola
AU  - Duduković, Aleksandar
PY  - 2007
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1062
AB  - Fluid dynamics studies of countercurrent gas - flowing solids - fixed bed contactors are presented in this review. The up-to-date research findings about the basic fluid dynamics parameters: flowing solids holdup, pressure drop and flow pattern are reviewed. Experimental results, as well as theoretical studies and mathematical models are observed and commented.
PB  - Association of the Chemical Engineers of Serbia
T2  - Chemical Industry & Chemical Engineering Quarterly
T1  - Fluid dynamics of gas - flowing solids - fixed bed contactors
EP  - 162
IS  - 3
SP  - 151
VL  - 13
DO  - 10.2298/CICEQ0703151N
ER  - 

@article{
author = "Nikačević, Nikola and Duduković, Aleksandar",
year = "2007",
abstract = "Fluid dynamics studies of countercurrent gas - flowing solids - fixed bed contactors are presented in this review. The up-to-date research findings about the basic fluid dynamics parameters: flowing solids holdup, pressure drop and flow pattern are reviewed. Experimental results, as well as theoretical studies and mathematical models are observed and commented.",
publisher = "Association of the Chemical Engineers of Serbia",
journal = "Chemical Industry & Chemical Engineering Quarterly",
title = "Fluid dynamics of gas - flowing solids - fixed bed contactors",
pages = "162-151",
number = "3",
volume = "13",
doi = "10.2298/CICEQ0703151N"
}

Nikačević, N.,& Duduković, A.. (2007). Fluid dynamics of gas - flowing solids - fixed bed contactors. in Chemical Industry & Chemical Engineering Quarterly
Association of the Chemical Engineers of Serbia., 13(3), 151-162.
https://doi.org/10.2298/CICEQ0703151N

Nikačević N, Duduković A. Fluid dynamics of gas - flowing solids - fixed bed contactors. in Chemical Industry & Chemical Engineering Quarterly. 2007;13(3):151-162.
doi:10.2298/CICEQ0703151N .

Nikačević, Nikola, Duduković, Aleksandar, "Fluid dynamics of gas - flowing solids - fixed bed contactors" in Chemical Industry & Chemical Engineering Quarterly, 13, no. 3 (2007):151-162,
https://doi.org/10.2298/CICEQ0703151N . .

TY  - JOUR
AU  - Rankovic, D.
AU  - Arsenijević, Zorana
AU  - Radić, Nenad
AU  - Grbić, Boško
AU  - Grbavčić, Željko
PY  - 2007
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/5496
AB  - The thermal desorption of saturated activated carbon discharged from an industrial adsorber and catalytic oxidation of desorbed products over a Pt/Al2O3 catalyst were investigated. The activated carbon is almost completely regenerated by flushing with air at 200 degrees C for 30 min. Desorbed products are fully oxidized over the Pt/Al2O3 catalyst above 275 degrees C.
PB  - Maik Nauka/Interperiodica/Springer, New York
T2  - Russian Journal of Physical Chemistry A
T1  - Removal of volatile organic compounds from activated carbon by thermal Desorption and catalytic combustion
EP  - 1391
IS  - 9
SP  - 1388
VL  - 81
DO  - 10.1134/S0036024407090075
ER  - 

@article{
author = "Rankovic, D. and Arsenijević, Zorana and Radić, Nenad and Grbić, Boško and Grbavčić, Željko",
year = "2007",
abstract = "The thermal desorption of saturated activated carbon discharged from an industrial adsorber and catalytic oxidation of desorbed products over a Pt/Al2O3 catalyst were investigated. The activated carbon is almost completely regenerated by flushing with air at 200 degrees C for 30 min. Desorbed products are fully oxidized over the Pt/Al2O3 catalyst above 275 degrees C.",
publisher = "Maik Nauka/Interperiodica/Springer, New York",
journal = "Russian Journal of Physical Chemistry A",
title = "Removal of volatile organic compounds from activated carbon by thermal Desorption and catalytic combustion",
pages = "1391-1388",
number = "9",
volume = "81",
doi = "10.1134/S0036024407090075"
}

Rankovic, D., Arsenijević, Z., Radić, N., Grbić, B.,& Grbavčić, Ž.. (2007). Removal of volatile organic compounds from activated carbon by thermal Desorption and catalytic combustion. in Russian Journal of Physical Chemistry A
Maik Nauka/Interperiodica/Springer, New York., 81(9), 1388-1391.
https://doi.org/10.1134/S0036024407090075

Rankovic D, Arsenijević Z, Radić N, Grbić B, Grbavčić Ž. Removal of volatile organic compounds from activated carbon by thermal Desorption and catalytic combustion. in Russian Journal of Physical Chemistry A. 2007;81(9):1388-1391.
doi:10.1134/S0036024407090075 .

Rankovic, D., Arsenijević, Zorana, Radić, Nenad, Grbić, Boško, Grbavčić, Željko, "Removal of volatile organic compounds from activated carbon by thermal Desorption and catalytic combustion" in Russian Journal of Physical Chemistry A, 81, no. 9 (2007):1388-1391,
https://doi.org/10.1134/S0036024407090075 . .

TY  - JOUR
AU  - Petkovska, Menka
AU  - Antov-Bozalo, Danijela
AU  - Marković, Ana
AU  - Sullivan, Patrick
PY  - 2007
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1128
AB  - Mathematical modeling of an Electric-Swing Adsorption (ESA) system (adsorption cycle with electrothermal desorption step, performed by direct heating of the adsorbent particles by passing electric current through them), with annular, radial-flow, cartridge-type fixed-bed and in-vessel condensation, is performed by using Comsol Multiphysics (TM) software. Three multiphysics models are built, in order to describe three stages of a compete ESA cycle: adsorption, electrothermal desorption before the start of condensation and electrothermal desorption with in-vessel condensation. In order to describe the complete ESA cycle the models for the three stages are integrated, by using a combination of Comsol Multiphysics (TM) and Matlab (TM). The models were successfully used for simulation of separate stages of the process and of the complete ESA cycles, as well as for investigation of the influences of the main operational parameters on the process performance.
PB  - Springer, Dordrecht
T2  - Adsorption-Journal of the International Adsorption Society
T1  - Multiphysics modeling of electric-swing adsorption system with in-vessel condensation
EP  - 372
IS  - 3-4
SP  - 357
VL  - 13
DO  - 10.1007/s10450-007-9028-2
ER  - 

@article{
author = "Petkovska, Menka and Antov-Bozalo, Danijela and Marković, Ana and Sullivan, Patrick",
year = "2007",
abstract = "Mathematical modeling of an Electric-Swing Adsorption (ESA) system (adsorption cycle with electrothermal desorption step, performed by direct heating of the adsorbent particles by passing electric current through them), with annular, radial-flow, cartridge-type fixed-bed and in-vessel condensation, is performed by using Comsol Multiphysics (TM) software. Three multiphysics models are built, in order to describe three stages of a compete ESA cycle: adsorption, electrothermal desorption before the start of condensation and electrothermal desorption with in-vessel condensation. In order to describe the complete ESA cycle the models for the three stages are integrated, by using a combination of Comsol Multiphysics (TM) and Matlab (TM). The models were successfully used for simulation of separate stages of the process and of the complete ESA cycles, as well as for investigation of the influences of the main operational parameters on the process performance.",
publisher = "Springer, Dordrecht",
journal = "Adsorption-Journal of the International Adsorption Society",
title = "Multiphysics modeling of electric-swing adsorption system with in-vessel condensation",
pages = "372-357",
number = "3-4",
volume = "13",
doi = "10.1007/s10450-007-9028-2"
}

Petkovska, M., Antov-Bozalo, D., Marković, A.,& Sullivan, P.. (2007). Multiphysics modeling of electric-swing adsorption system with in-vessel condensation. in Adsorption-Journal of the International Adsorption Society
Springer, Dordrecht., 13(3-4), 357-372.
https://doi.org/10.1007/s10450-007-9028-2

Petkovska M, Antov-Bozalo D, Marković A, Sullivan P. Multiphysics modeling of electric-swing adsorption system with in-vessel condensation. in Adsorption-Journal of the International Adsorption Society. 2007;13(3-4):357-372.
doi:10.1007/s10450-007-9028-2 .

Petkovska, Menka, Antov-Bozalo, Danijela, Marković, Ana, Sullivan, Patrick, "Multiphysics modeling of electric-swing adsorption system with in-vessel condensation" in Adsorption-Journal of the International Adsorption Society, 13, no. 3-4 (2007):357-372,
https://doi.org/10.1007/s10450-007-9028-2 . .

TY  - JOUR
AU  - Ilić, Milica
AU  - Petkovska, Menka
AU  - Seidel-Morgenstern, Andreas
PY  - 2007
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1142
AB  - The nonlinear frequency response of a chromatographic column for the adsorption of two dissolved components is analyzed using the concept of higher order frequency response functions (FRFs) which is based on the Volterra series and generalized Fourier transform. By applying this concept a nonlinear model of a system is replaced by an infinite series of the FRFs of the first, second, etc. order. The FRFs up to the third order are derived theoretically starting from the equilibrium-dispersive model, which is used for description of a chromatographic column, and applying the harmonic probing method. The functions that relate outlet concentration changes of each component to the corresponding inlet concentration changes are derived. At the inlet of a chromatographic column, it is considered: (a) the concentration change of one of the components keeping the concentration of the other component constant and (b) the concentration change of both components keeping their ratio constant. The FRFs are calculated numerically for different steady-state concentrations and relative mixture compositions. It has been found that, despite certain differences in initial conditions, the FRFs exhibit similar behavior. For higher frequencies, the amplitudes of the FRFs tend to zero and phases to -infinity. In the low frequency range, which is of interest for investigation of equilibrium parameters, these functions have similar behavior, but tend to different asymptotic values. Correlations between coefficients of competitive adsorption isotherms, i.e. partial isotherm derivatives, and the derived FRFs are established. This theoretical result offers the potential to use the analysis of the nonlinear frequency response of a chromatographic column for estimation of competitive adsorption isotherms.
PB  - Springer, New York
T2  - Adsorption-Journal of the International Adsorption Society
T1  - Theoretical investigation of the adsorption of a binary mixture in a chromatographic column using the nonlinear frequency response technique
EP  - 567
IS  - 5-6
SP  - 541
VL  - 13
DO  - 10.1007/s10450-007-9035-3
ER  - 

@article{
author = "Ilić, Milica and Petkovska, Menka and Seidel-Morgenstern, Andreas",
year = "2007",
abstract = "The nonlinear frequency response of a chromatographic column for the adsorption of two dissolved components is analyzed using the concept of higher order frequency response functions (FRFs) which is based on the Volterra series and generalized Fourier transform. By applying this concept a nonlinear model of a system is replaced by an infinite series of the FRFs of the first, second, etc. order. The FRFs up to the third order are derived theoretically starting from the equilibrium-dispersive model, which is used for description of a chromatographic column, and applying the harmonic probing method. The functions that relate outlet concentration changes of each component to the corresponding inlet concentration changes are derived. At the inlet of a chromatographic column, it is considered: (a) the concentration change of one of the components keeping the concentration of the other component constant and (b) the concentration change of both components keeping their ratio constant. The FRFs are calculated numerically for different steady-state concentrations and relative mixture compositions. It has been found that, despite certain differences in initial conditions, the FRFs exhibit similar behavior. For higher frequencies, the amplitudes of the FRFs tend to zero and phases to -infinity. In the low frequency range, which is of interest for investigation of equilibrium parameters, these functions have similar behavior, but tend to different asymptotic values. Correlations between coefficients of competitive adsorption isotherms, i.e. partial isotherm derivatives, and the derived FRFs are established. This theoretical result offers the potential to use the analysis of the nonlinear frequency response of a chromatographic column for estimation of competitive adsorption isotherms.",
publisher = "Springer, New York",
journal = "Adsorption-Journal of the International Adsorption Society",
title = "Theoretical investigation of the adsorption of a binary mixture in a chromatographic column using the nonlinear frequency response technique",
pages = "567-541",
number = "5-6",
volume = "13",
doi = "10.1007/s10450-007-9035-3"
}

Ilić, M., Petkovska, M.,& Seidel-Morgenstern, A.. (2007). Theoretical investigation of the adsorption of a binary mixture in a chromatographic column using the nonlinear frequency response technique. in Adsorption-Journal of the International Adsorption Society
Springer, New York., 13(5-6), 541-567.
https://doi.org/10.1007/s10450-007-9035-3

Ilić M, Petkovska M, Seidel-Morgenstern A. Theoretical investigation of the adsorption of a binary mixture in a chromatographic column using the nonlinear frequency response technique. in Adsorption-Journal of the International Adsorption Society. 2007;13(5-6):541-567.
doi:10.1007/s10450-007-9035-3 .

Ilić, Milica, Petkovska, Menka, Seidel-Morgenstern, Andreas, "Theoretical investigation of the adsorption of a binary mixture in a chromatographic column using the nonlinear frequency response technique" in Adsorption-Journal of the International Adsorption Society, 13, no. 5-6 (2007):541-567,
https://doi.org/10.1007/s10450-007-9035-3 . .