Adsorption of malachite green by calcined kaolin as adsorbent: optimization, thermodynamic and kinetics studies

Abstract

The calcined kaolin was used as adsorbent, and the adsorption effect on malachite green (MG) was studied by changing the oscillation time, pH value, calcined kaolin dosage and temperature, respectively. The results show that calcined kaolin has good adsorption effect on MG. Under the conditions of oscillation time of 180 min, calcined kaolin dosage of 16 g/L, initial MG concentration of 100 mg/L and neutral pH, the MG adsorption rate could reach 98.9%. The adsorption equilibrium data of MG on calcined kaolin conformed to Langmuir and Freundlich isotherms. According to the results of adsorption thermodynamics, MG adsorption on calcined kaolin is endothermic and a spontaneous process. MG adsorption on calcined kaolin could be described by quasi-first-order better.