Modelling Cd(II) removal from aqueous solutions by adsorption on a highly mineralized peat.: Batch and fixed-bed column experiments

This paper evaluates the potential use of a locally available organic soil amendment as a low-cost adsorbent. The removal of cadmium from aqueous solutions was studied by means of kinetic, batch and fixed-bed experiments. Batch experiments were conducted to evaluate the process kinetics and the removal equilibrium over a broad pH range. Pseudo-second-order kinetics and Freundlich equilibrium parameters were obtained. Six column experiments were carried out at different flow-rates and feed concentrations. Breakthrough curves showed higher metal retention than expected from the batch adsorption isotherms. Column modelling assuming rate-controlled pore diffusion was successfully performed. The adsorption process was reversed, regenerating the columns by eluting the cadmium using 0. 1 mol dm(-3) hydrochloric acid. The high retention capacity together with the favourable structural characteristics indicated that this material could be used as an effective and low-cost adsorbent for treatment of wastewaters containing heavy metals. (c) 2006 Society of Chemical Industry