Reduction of Hexavalent Chromium in Water Using Iron-Aluminum Bimetallic Particles

Abstract

Metal finishing wastewater containing chromium was conventionally treated by chemical precipitation and ion exchange techniques. Zero-valent metals such as iron, aluminum, zinc that possess high reduction potentials are frequently employed to remediate and process the contaminated groundwater. Iron-aluminum bimetallic metal (Fe-Al) is developed to improve the reduction capacity of Fe, Al is regarded as the electron supplier to prevent the precipitates formed on the surface of Fe. The aim of this research is to study the performance of Fe-Al on the reduction of hexavalent chromium ion (Cr6+) in water under several operation parameters including initial pH value, dosage of Fe-Al to Cr6+ ratio (Fe-Al/Cr+6), and Fe contents of Fe-Al particles. The results indicated that the sizes and specific surface area of Fe-Al particles increased with higher Fe content. The metal species on the surface of Fe-Al particles were identified by an x-ray diffraction spectrometer (XRD). Reduction of Cr6+ with Fe-Al particles consumes the H+ in water resulting in the increase of pH value with the reaction time. The study showed that the reduction potentials of Fe-Al on Cr6+ are promoted under acidic state and with higher dosage of Fe-Al/Cr+6.