Abstract

This study proposes a Jordanian Pottery (Pot-Jo) as a low cost adsorbent for the removal of chromium from aqueous solutions. The effect of contact time, initial concentration of Cr(VI), temperature and ionic strength on the adsorption of Cr(VI) onto Pot-Jo were studied and discussed. The equilibrium (q_e) of adsorption of Cr(VI) onto pottery were found to be 20.287, 17.55, and 13.577 mg Cr(VI) per gram of pottery at temperatures 25, 35, and 45°C, respectively. Five kinetic models, the pseudo first-order equation, the pseudo second-order equation, the Elovich equation, the Ritchie’s equation, and the intraparticle diffusion model were tested with respect to their adequacy to describe the adsorption process. The mechanism of adsorption was investigated by using the intraparticle diffusion model. It was found that there was no significant effect of the ionic strength on the removal of Cr(VI) from its solutions. Kinetic parameters, rate constants, equilibrium adsorption capacities and correlation coefficients, for each kinetic equation were calculated and discussed. Activation energy values were found to be between 13.85 and 33.10 kJ mol^-1. The Ritchie and pseudo-first order kinetic equation were found to correlate the experimental data well. The rate determining step is well described by intraparticle diffusion process. The k_id values ranging from 1.326 to 0.963 mgg^-1min^-1/2.

Key words: Chromium (VI), Sorption kinetics, Pseudo-second order, Lagergren, Tempkin.