Application of Kinetic Models for Heavy Metal Adsorption in the Single and Multicomponent Adsorption System

The overall rate of heavy metal adsorption on the porous sorbent consists of three separate steps: external mass transport, intraparticle diffusion, and adsorption on active sites. The pseudo-first-order model, pseudo-second-order model, and film-pore volume diffusion model are three types of kinetic models that have developed based on these steps. In this research, studies for predicting these kinetic models from the concentration decay curves of Pb2+, Cd2+, Ni2+, and Zn2+ were done on a batch adsorption process. Evaluation of the models prediction was performed by two separate reported experimental data. There is limited literature on the application of film-pore volume diffusion model for multicomponent adsorption systems in previous modeling studies; hence, the performance of this kinetic model was evaluated in this study using data from concentration decay curves of multicomponent adsorption systems. Investigation showed that for different adsorption systems, the application of the film-pore volume diffusion model has decreased the average relative error between 1-83% and 1-40% in comparison to the pseudo-first-order and pseudo-second-order model, respectively. More accurate prediction of the film-pore volume diffusion model is related to consideration of external mass transfer resistance on prediction. Effective pore volume diffusivity of different metal ions was calculated between 0.004 x 10(-6) cm(2) s(-1) and 2.2 x 10(-6) cm(2) s(-1) for a different adsorption system.