The reductive transformation of 4-cyanonitrobenzene (4-CNB) was examined in batch suspensions of goethite containing cysteine at pH 6-8. Experimental results demonstrate that cysteine promotes the reductive dissolution of ferric oxides, which in turn, facilitates the reductive transformation of 4-CNB at all pH values examined. Transformation rates are dependent upon cysteine concentrations, surface loading, and pH. In comparing particle size, it was observed that the nano-sized particles facilitated the fastest rates of reduction, followed by the intermediate-sized rods, and the micro-sized rods. The results of this study provide evidence that naturally occurring organic molecules play an indirect role in the transformation of reducible organic compounds. Generally, a neutral pH is less favorable for the reductive dissolution of ferric oxides and more favorable for Fe(II) adsorption, but neutral pH conditions can generate sufficient concentrations of Fe(II). Results of this effort may elucidate the fate of reducible organic compounds in aqueous systems.

Role of cysteine concentration and particle size in the reductive dissolution of goethite and the subsequent transformation of nitrosubstituted compounds

244th National Meeting (2012)

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