Equilibrium and kinetic studies on the sorption of acidic dye by macroporous anion exchanger

Abstract

Synthetic diazo dye Acid Blue 29 was removed from aqueous solution using the strongly basic anion exchanger of macroporous structure – Purolite A-520E. The influence of phase contact time (1–180 min), anion exchanger dosage (0.25–1.0 g), solution pH (1–8), initial dye concentration (100–500 mg/L) and temperature (20–50 °C) was studied by the batch method. Additionally, the obtained results were compared with those for the activated carbon Purolite AC-20G. The amounts of Acid Blue 29 adsorbed at equilibrium using the strongly basic anion exchanger were equal to 9.9, 19.9, 29.9 and 48.2 mg/g for the dye solutions of the initial concentrations 100, 200, 300 and 500 mg/L, respectively. The experimental data were analyzed by means of the Langmuir, Freundlich and Temkin models of adsorption. The maximum monolayer capacity Q0 for sorption of the dye on the activated carbon was 30.2 mg/g. The Q0 obtained for the strongly basic anion exchanger was ten times higher (321.5 mg/g) than that obtained for Purolite AC-20G. The kinetic data obtained at different concentrations were modelled using the pseudo-first order, pseudo-second order and intraparticle diffusion equations. The experimental data were well described by the pseudo-second order kinetic model.