Thermodynamics and kinetics of Zn(II) adsorption on crosslinked starch phosphates

Crosslinked starch phosphates (CSP) with different contents of phosphate groups were used to adsorb Zn(II) from aqueous solution. Effects of adsorption time, initial concentration of Zn(II) ion, and temperature on the adsorption of Zn(II) by CSP were studied, and the equilibrium, thermodynamics and kinetics of the adsorption process were further investigated. It showed that crosslinked starch phosphates can effectively remove Zn(II) from the solution. The adsorption equilibrium data correlate well with the Langmuir isotherm model with a maximum adsorption capacity of 2.00 mmol g−1. The adsorption of Zn(II) on CSP is endothermic in nature. The pseudo-first-order and pseudo-second-order kinetic models were applied to test the experimental data. The pseudo-second-order kinetic model provided a better correlation of the experimental data in comparison with the pseudo-first-order model.