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| Biogeochemical Cr(VI) reduction in groundwater enhanced by emulsified vegetable oil |
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Abstract Natural fine sands was used as simulated aquifer media and emulsified vegetable oil as electron donor in the experiments to investigate the process and mechanisms of the biogeochemical reduction of hexavalent chromium. The experimental results showed that the emulsified vegetable oil caused a slightly pH drop, and the final pH reached 6.59; a reductive condition could be maintained for a long term, and the final Eh declined to -158.6mV. Emulsified vegetable oil could accelerate the dissimilatory iron reduction process of intrinsic microorganism; the ferric in fine sand would be reduced to ferrous and hexavalent chromium removal coupled. The hexavalent chromium and total chromium was removed absolutely within 14 and 28 days, respectively. The accumulation of Fe (II) exert profound influence on the redox condition of the reaction system. The final Fe (II) concentration was up to 44.40mg/L, and 48.9% of emulsified vegetable oil was consumed at the end of experiment. Structural characteristics analysis of sands was studied by X-ray diffractometer (XRD) and X-ray photoelectron spectra (XPS); the results showed that the trivalent chromium existed as the amorphous formation of Fe-Cr coprecipitation.
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Received: 25 October 2014
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