Removal Of Aqueous Molybdenum By Zero Valent Iron

Mo is a significant nutrient element for a variety of biological functions, but it may be potentially toxic at high concentration. In recent years, a sharp enrichment of Mo occurred in some water bodies of areas at a result of Mo mining. Therefore, it is importance to remove Mo from polluted water using inexpensive, effective and friendly methods.Zero-valent iron was considered as an effective material for remediation of certain organic and inorganic pollutants in groundwater. The removal mechanism may comprise of adsorption, complexation, reduction, precipitation for aqueous As, Cr and Se. Mo has some similar characteristic with these elements, thus ZVI will be applicable for Mo removal. Currently, there is a lack of systemic and through study regarding Mo removal by zero valent iron, and little is known about the mechanism.In this study, batch tests were performed to investigate the surface reactions of Mo on zero-valent iron. The effects of time, zero-valent iron dose, temperature, pH value, inorganic anions, cations and organic anions were examined. The results showed that increasing zero-valent iron dose and temperature can enhance the removal rate of molybdate; the maximum removal rate was 96% at pH = 2.0, which decreased with the increase of pH value. It was also found that inorganic and organic anions restrained strongly with molybdate removal, but organic cations accelerated the molybdate removal.In order to elucidate the mechanism, a series of study were conducted including desorption of Mo, release of iron ion, scanning electron microscopy analysis, electron probe microanalysis and X-ray diffraction analysis. The results revealed revealed that adsorption and chemical precipitation mechanism are involved during the reaction process.