Kinetic investigation of the immobilization of chromotropic acid derivatives onto anion exchange resin
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The adsorption kinetics of pyrazol- (PACA) and imidazol-azo-chromo-tropic acid (IACA) onto Dowex 1-X8 resin, as a function of the dye concentration and temperature were investigated at pH 4.5. The pseudo-first- and second-order kinetic models and intraparticle diffusion model were used to describe the obtained kinetic data. The adsorption rate constants were found to be in the order of magnitude 10(-2) min(-1) for all of the used kinetics models. The adsorption capacity increases with increasing initial dye concentration. The study of adsorption kinetics at different temperatures (in the range from 5 to 25 degrees C) reveals an increase in the rate of adsorption and adsorption capacity with increasing temperature. The activation energy (in the case of PACA 16.6 kJ/mol, and for IACA 11.3 kJ/mol) was determined using the Arrhenius dependence. Electrostatic interactions between the dye and resin beads were shown to be the adsorption mechanism.