TY  - JOUR
AU  - Miladinović, Zoran P.
AU  - Zakrzewska, Joanna
AU  - Kovacević, Branimir T.
AU  - Miladinović, Jelena
PY  - 2014
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/2812
AB  - In this study, in situ Al-27 NMR spectroscopy was used to gain detailed information concerning kinetics of zeolite A crystallization. Changes of relative intensity and width at half-height of NMR lines at 59 ppm ascribed to Al(OSi)(4) solid structures units and at 79 ppm to Al(OH) T ions in liquid phase during crystallization, were observed. Normalized curves for series of synthesis, performed under different batch molar composition, were used for kinetic analysis applying Sharp and Hancock approach. The influence of total batch Na2O concentration (H2O/Na20 was 20 and 32) for three specific batch SiO2/Al2O3 molar ratios (1.7, 2.0 and 2.5) on the kinetic parameters was investigated. Kinetic analysis of line at 79 ppm provided values of parameter n that ranged from 0.93 to 1.97 indicating contribution of both diffusion and phase boundary controlled mechanisms, depending on batch SiO2/Al2O3 molar composition. On the other hand, analysis of line at 59 ppm showed strong correlation to Na2O batch content. Values of n from 1.94 to 3.34 for syntheses performed at lower alkalinity conditions (H2O/Na2O = 32) indicate Avrami-Erofe'ev nucleation and crystal growth model. Almost dominant presence of diffusion mechanism for synthesis conducted at higher alkalinity conditions (H2O/Na2O = 20) was verified by obtained values of n gathered around 1.5.
PB  - Elsevier Science Bv, Amsterdam
T2  - Microporous and Mesoporous Materials
T1  - In situ Al-27 NMR kinetic investigation of zeolite A crystallization
EP  - 142
SP  - 131
VL  - 195
DO  - 10.1016/j.micromeso.2014.04.022
ER  - 

@article{
author = "Miladinović, Zoran P. and Zakrzewska, Joanna and Kovacević, Branimir T. and Miladinović, Jelena",
year = "2014",
abstract = "In this study, in situ Al-27 NMR spectroscopy was used to gain detailed information concerning kinetics of zeolite A crystallization. Changes of relative intensity and width at half-height of NMR lines at 59 ppm ascribed to Al(OSi)(4) solid structures units and at 79 ppm to Al(OH) T ions in liquid phase during crystallization, were observed. Normalized curves for series of synthesis, performed under different batch molar composition, were used for kinetic analysis applying Sharp and Hancock approach. The influence of total batch Na2O concentration (H2O/Na20 was 20 and 32) for three specific batch SiO2/Al2O3 molar ratios (1.7, 2.0 and 2.5) on the kinetic parameters was investigated. Kinetic analysis of line at 79 ppm provided values of parameter n that ranged from 0.93 to 1.97 indicating contribution of both diffusion and phase boundary controlled mechanisms, depending on batch SiO2/Al2O3 molar composition. On the other hand, analysis of line at 59 ppm showed strong correlation to Na2O batch content. Values of n from 1.94 to 3.34 for syntheses performed at lower alkalinity conditions (H2O/Na2O = 32) indicate Avrami-Erofe'ev nucleation and crystal growth model. Almost dominant presence of diffusion mechanism for synthesis conducted at higher alkalinity conditions (H2O/Na2O = 20) was verified by obtained values of n gathered around 1.5.",
publisher = "Elsevier Science Bv, Amsterdam",
journal = "Microporous and Mesoporous Materials",
title = "In situ Al-27 NMR kinetic investigation of zeolite A crystallization",
pages = "142-131",
volume = "195",
doi = "10.1016/j.micromeso.2014.04.022"
}

Miladinović, Z. P., Zakrzewska, J., Kovacević, B. T.,& Miladinović, J.. (2014). In situ Al-27 NMR kinetic investigation of zeolite A crystallization. in Microporous and Mesoporous Materials
Elsevier Science Bv, Amsterdam., 195, 131-142.
https://doi.org/10.1016/j.micromeso.2014.04.022

Miladinović ZP, Zakrzewska J, Kovacević BT, Miladinović J. In situ Al-27 NMR kinetic investigation of zeolite A crystallization. in Microporous and Mesoporous Materials. 2014;195:131-142.
doi:10.1016/j.micromeso.2014.04.022 .

Miladinović, Zoran P., Zakrzewska, Joanna, Kovacević, Branimir T., Miladinović, Jelena, "In situ Al-27 NMR kinetic investigation of zeolite A crystallization" in Microporous and Mesoporous Materials, 195 (2014):131-142,
https://doi.org/10.1016/j.micromeso.2014.04.022 . .

TY  - JOUR
AU  - Marković, Slobodanka
AU  - Đonlagić, Jasna
AU  - Zakrzewska, Joanna
AU  - Dunjić, Branko
PY  - 1999
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/237
AB  - C-13-NMR spectroscopy and gel-permeation chromatography studies were carried out on different samples of typical commercial phenol-formaldehyde novolac resins. Six random novolac resins (NLO 1-6), with decreasing ratios of phenol/formaldehyde from 1:0.75 to 1:0.85, were prepared in the presence of oxalic acid at two different concentratons. A high-ortho novolac resin (NL-OO') was synthesized in the pH range 4-6 using zinc acetate (Zn(OAc)(2)), as catalyst. An improved description of the chemical structure, in terms of composition, the number of free para- and ortho-positions, the isomeric distribution, the degree of polymerization, the number average molecular weight, the degree of branching and molecular weight distribution, was obtained.
PB  - Serbian Chemical Society, Belgrade
T2  - Journal of the Serbian Chemical Society
T1  - Study of the structure of phenol-formaldehyde novolac resins by NMR spectroscopy and gel-permeation chromatography
EP  - 189
IS  - 3
SP  - 177
VL  - 64
UR  - https://hdl.handle.net/21.15107/rcub_technorep_237
ER  - 

@article{
author = "Marković, Slobodanka and Đonlagić, Jasna and Zakrzewska, Joanna and Dunjić, Branko",
year = "1999",
abstract = "C-13-NMR spectroscopy and gel-permeation chromatography studies were carried out on different samples of typical commercial phenol-formaldehyde novolac resins. Six random novolac resins (NLO 1-6), with decreasing ratios of phenol/formaldehyde from 1:0.75 to 1:0.85, were prepared in the presence of oxalic acid at two different concentratons. A high-ortho novolac resin (NL-OO') was synthesized in the pH range 4-6 using zinc acetate (Zn(OAc)(2)), as catalyst. An improved description of the chemical structure, in terms of composition, the number of free para- and ortho-positions, the isomeric distribution, the degree of polymerization, the number average molecular weight, the degree of branching and molecular weight distribution, was obtained.",
publisher = "Serbian Chemical Society, Belgrade",
journal = "Journal of the Serbian Chemical Society",
title = "Study of the structure of phenol-formaldehyde novolac resins by NMR spectroscopy and gel-permeation chromatography",
pages = "189-177",
number = "3",
volume = "64",
url = "https://hdl.handle.net/21.15107/rcub_technorep_237"
}

Marković, S., Đonlagić, J., Zakrzewska, J.,& Dunjić, B.. (1999). Study of the structure of phenol-formaldehyde novolac resins by NMR spectroscopy and gel-permeation chromatography. in Journal of the Serbian Chemical Society
Serbian Chemical Society, Belgrade., 64(3), 177-189.
https://hdl.handle.net/21.15107/rcub_technorep_237

Marković S, Đonlagić J, Zakrzewska J, Dunjić B. Study of the structure of phenol-formaldehyde novolac resins by NMR spectroscopy and gel-permeation chromatography. in Journal of the Serbian Chemical Society. 1999;64(3):177-189.
https://hdl.handle.net/21.15107/rcub_technorep_237 .

Marković, Slobodanka, Đonlagić, Jasna, Zakrzewska, Joanna, Dunjić, Branko, "Study of the structure of phenol-formaldehyde novolac resins by NMR spectroscopy and gel-permeation chromatography" in Journal of the Serbian Chemical Society, 64, no. 3 (1999):177-189,
https://hdl.handle.net/21.15107/rcub_technorep_237 .