Feasibility of vanadium(IV) adsorption using natural bentonite: optimization, equilibrium and kinetics

Because of the increasing use of vanadium in different industries, including alloys and steel manufacturing, catalysts, and electrochemical coating, the presence of vanadium as toxic metal in industrial effluents has become a worldwide environmental concern. In this study, the potential of natural bentonite as an available adsorbent for vanadium(IV) ions separation was investigated. The main properties of natural bentonite were characterized using analysis such as specific surface area measurement, scanning electron microscopy, and Fourier-transform infrared spectroscopy, X-ray diffraction, and X-ray fluorescence. The influence of main adsorption parameters such as initial vanadium(IV) concentration, solution pH and adsorbent dose were also investigated. The optimization of these parameters was performed by central composite design based on response surface methodology. Based on the results, the maximum vanadium(IV) adsorption obtained at optimum conditions was 43% for initial vanadium(IV) concentration (113 mg L–1), pH (2), adsorbent dosage (3.11 g L–1), and contact time (180 min). The vanadium adsorption on natural benton-ite was firmly confirmed by the pseudo-second-order kinetic model. The equilibrium isotherm data was fitted with the Langmuir model with significant accuracy.