Isotherm and kinetic studies on the adsorption of humic acid onto chitosan-H 2SO 4 beads

Abstract

A batch adsorption system was applied to study the adsorption of humic acid onto chitosan-H 2SO 4 beads. Different parameters affecting the adsorption capacity such as initial pH, agitation period, different temperatures and different initial concentrations of humic acid were studied. The adsorption of humic acid onto chitosan-H 2SO 4 beads agreed well with the non-linear Langmuir, Freundlich and Sips isotherm models. Based on the Langmuir isotherm model, the maximum adsorption capacities attained by chitosan-H 2SO 4 beads at 300, 310 and 320 K were 377.40, 363.50 and 342.50 mg/g, respectively. Different temperatures affected the adsorption process and it was found that the adsorption process was endothermic in nature. The pseudo-second-order kinetic model, which assumed that chemisorption, was the rate-limiting step best described the adsorption of humic acid onto chitosan-H 2SO 4 beads.