Kinetics and mechanism of the sorption of some aromatic amines onto amberlite IRA-904 anion-exchange resin

The kinetics of the sorption of aromatic amines such as o-aminophenol (o-AP ), o-phenylenediamine (o-PDA), and phenylenediamine (p-PDA) onto Amberlite anion-exchange resin in chloride form was investigated in batch experiments spectrophotometrically at different temperatures. The sorption rate is zer o order in all amines sorbed, increasing directly in the order: p-PDA < o-P DA < o-AP, which corresponds to the sequence of the electrostatic contribut ions to the sorption interactions. The attainment of sorption equilibrium o f aromatic amines is seen to be similar. The diffusion coefficients (D) hav e been calculated by using Fick's equation from the second portions of the sorption/desorption curves; D values ranged from 0.7 to 2.8 x 10(-9) cm(2)/ s. These results, reflecting the diffusion mechanism, were ascribed to intr aparticle diffusion. Arrhenius parameters for the diffusion process and the thermodynamic quantities for the process of equilibrium sorption have been estimated. The effect of a chemical oxidation reaction on intraparticle di ffusion was investigated by measuring the intraparticle diffusion of amines during the redox reaction. (C) 2000 Academic Press.