柠檬配体促进Fe(II)氧化产生羟自由基并氧化As(III)

In the natural environment, the interaction between surface water and groundwater is very common. Entering of aerobic surface water into the anoxic groundwater leads to the elevation of reduction potential of the groundwater. At the same time, the low-molecular weight organic ligands included in the water complex with ferrous, altering the reactions. This study investigated the production of hydroxyl radicals upon the oxygenation of Fe(II) complex and evaluated the environmental impact on arsenic oxidation in the lab. Fe(II) at 0.25 mmol/L was oxidized in the presence of different concentritions of citrate（0-0.5 mmol/L). Results show that the presence of citrate increased the production of hdyroxyl radicals dramatically. As the concentration of citric ligand increased, the production of hdyroxyl radicals increased correspondingly. At pH values of 6.0, 7.0 and 7.5, the maximum concentrations of hydroxyl radicals produced reached 32.168, 24.143 and 18.491 μmol/L, respectively using sulfate as the background electrolyte, and attained 13.124 μmol/L using bicarbnate as the background electrolyte. Most As(III) in the solution was oxidized to As(V) by the hydroxyl radicals. The oxidation efficiency was 65.56% and 82.58% in the presence and absence of bicarbnate, respectively.