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    Effects of different molecular weights of polystyrene on the acylation reaction and on the reaction kinetics
    (WILEY, 2005) Ahmetli, G; Yazicigil, Z; Kocak, A; Kurbanli, R
    In this Study, chemical modification reactions of polystyrenes with different molecular weights with maleic and acetic anhydrides in the presence of a catalyst [BF3 . O(C2H5)(2)] were examined. The number of polyfunctional groups bound to the polymer structure changed according to the molecular weight of the polymer, and more functional groups were bound to lower molecular weight polystyrenes. The bound functional groups and their amounts were determined with spectral and chemical analysis methods. The effects of the molecular weights of the polystyrenes on the chemical modification kinetics with magnetic and acetic anhydrides in the presence of BF3 . O(C2H5)(2) were examined. The kinetic parameters of the reaction and its activation energy were calculated. The higher the molecular weight of polystyrene was, the lower its rate of modification was and the greater its activation energy was; the lower the molecular weight of polystyrene was, the higher its rate of modification was and the lower its activation energy was. (C) 2005 Wiley Periodicals, Inc.
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    Recovery of metals from complexed solutions by electrodeposition
    (ELSEVIER SCIENCE BV, 2006) Oztekin, Y; Yazicigil, Z
    Electrolytic recovery of metals from aqueous solutions containing complexing chelating agents such as EDTA, NTA, and citrate was studied in a two-chamber cell separating with a commercial cation-exchange membrane (CEM). Equimolar solutions of metal and a chelating agent as a catholyte and NaNO3 as an anolyte were used; the effect of current densities, initial catholyte and anolyte pH, metal concentration and the type of the CEM, chelating agent and metal on the recovery of metals was determined. The recovery of metal increased with higher initial anolyte pH, concentration and current density, whereas it decreased with lower initial catholyte pH. The results show that electro-deposition seems to be an applicable method for the recovery of metals under appropriate conditions.