Adsorption kinetics of phosphate from aqueous solutions onto modified corn residue

The adsorption kinetics of phosphate from aqueous solutions onto modified corn residue was studied in a batch reactor. The influence of initial pH, concentration and temperature to adsorption effect were investigated. In addition, the kinetic data were fitted by pseudo-first-order equation, pseudo-second-order equation, modified pseudo-first-order equation and intra-particle diffusion model, and the respective characteristic rate constants were presented. The results showed that the adsorption data fitted Freundlich isotherm model, and the maximum adsorption capacity of phosphate would decrease with the temperature increasing. Furthermore, the adsorption process could reached equilibrium in 30 minutes, and the pseudo-second-order equation and intra-particle diffusion model generated the best agreement with the experimental data for the adsorption systems. The intra-particle diffusion was the main rate-controlling step. With increasing initial concentration, the rate constant of pseudo-second-order equation decreases and that of intra-particle diffusion model increases. The adsorption kinetic analyses could be of a great practical value for the technological applications of phosphate removal from aqueous solutions.