Equilibrium and kinetic studies on the adsorption of acidic dye by the gel anion exchanger.

In the present study, the gel anion exchanger Purolite A-850 of N(+)(CH(3))(3) functional groups was used in order to remove the acidic dye (Acid Blue 29) from aqueous solutions. Batch experiments were conducted to study the effect of phase contact time (1-180 min), initial concentration of dye (100-500 mg/L), solution pH (1-8), anion exchanger dosage (0.25-1.0 g) as well as temperature (20-40 degrees C). The contact time necessary to reach equilibrium was 40 min with the exception for the solution of the initial concentration 500 mg/L. The amounts of Acid Blue 29 adsorbed at equilibrium using the strongly basic anion exchanger were equal to 9.97, 19.97, 29.96 and 49.90 mg/g for the dye solutions of the initial concentrations 100, 200, 300 and 500 mg/L, respectively. The equilibrium sorption capacity slightly increased when the temperature of dye solution increased from 20 to 40 degrees C. The experimental data were analyzed by the Langmuir, Freundlich and Temkin models of adsorption. The adsorption isotherm data were fitted well to the Langmuir isotherm and the monolayer adsorption capacity was found to be 83.303 mg/g at 20 degrees C. The value of R(L) was equal to 0.00054 (favourable). The kinetic data obtained at different concentrations were modeled 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.