Adsorption of itaconic acid from aqueous solutions onto alumina

Abstract

Itaconic acid, IA (C5H6O4), was investigated as a potential flocculant for the aqueous processing of alumina powders. The adsorption of IA, as a function of its concentration and pH value of the solution, onto the alumina surface was studied by the solution depletion method. The stability of the suspensions in the presence of itaconic acid was evaluated in light of the surface charge of the alumina powder used, the degree of dissociation of IA, as well as the sedimentation behavior and rheology of the suspensions. It was found that the adsorption process is extremely pH dependent; the maximum adsorption of IA onto alumina surface occurring at a pH close to the value of the first IA dissociation constant, pKa1. Also, IA does not influence the value of the point of zero charge of alumina. It was shown that IA represents an efficient flocculant for concentrated acidic alumina suspensions.

Izučavana je primena itakonske kiseline, IK (C5H6O4), kao potencijalnog flokulanta, za vodeno procesiranje prahova aluminijum-oksida. Adsorpcija itakonske kiseline na površini aluminijum-oksida izučavana je u funkciji koncentracije i pH rastvora. Stabilnost suspenzija aluminijum-oksida u prisustvu itakonske kiseline objašnjena je uzimajući u obzir površinsko naelektrisanje aluminijum-oksida, stepen disocijacije itakonske kiseline, sedimentaciono ponašanje i reološka svojstva suspenzija. Nađeno je da adsorpcija IK jako zavisi od pH. Maksimalna adsorpcija IK na površini aluminijum-oksida dešava se pri pH vrednosti bliskoj vrednosti prve konstante disocijacije IK, pKa1. Dodatak itakonske kiseline ne utiče na vrednost tačke nultog naelektrisanja aluminijum-oksida. Pokazano je da je IK efikasan flokulant za koncentrovane, kisele suspenzije aluminijum-oksida.