Adsorptive Performance of Surface-Modified Montmorillonite in Vanadium Removal from Mine Water

Montmorillonite modified with hexadecyltrimethylammonium bromide was used to remove vanadium (V) from synthetic and real mine water. Fourier transform infrared, X-ray diffraction, and scanning electron microscopy were used to characterise the adsorbent before and after adsorption, while the amount of V adsorbed was determined by ICP-OES. Batch adsorption was evaluated for dissolved V concentrations of 50-320 mg/L and V tailings seepage water from a South African mine. Adsorption capacity was affected by solution pH, temperature, sorbent mass, and the initial concentration. Electrical conductivity of the mine water before and after adsorption was measured to estimate the total dissolved solids. Equilibrium isotherm results revealed that V sorption follows the Freundlich isotherm, indicating that the sorbent surface was heterogeneous. A pseudo-second order kinetic model gave the best fit to the kinetic experimental data. The results of this study allow us to predict uptake efficiency of South African montmorillonite for V removal from mine water. However, the best adsorbent for the uptake of V or other contaminants will depend on the effluent to be treated.