The Effects of Some Inorganic and Organic Species on Oxidation with Atmospheric Oxygen of Manganese in Natural Water

Abstract

Manganese (Mn) is an important element in environmental geochemistry. In many natural aquatic systems, high concentrations of manganese are present with organic and inorganic matters. The oxidation of Mn(II) in aqueous systems has been extensively studied. But inorganic and organic matter effects on oxidation have not been fully clarified. It is clear that Mn(II) oxidation in the presence of inorganic and organic matter runs differently. The aim of this study is to investigate the effects of some inorganic species (Mg(II), Ca(II), Ni(II), Zn(II)) and also some organic species (gallic acid and tartaric acid) on oxidation of manganese Mn(II) with atmospheric oxygen in natural water. Experimental studies have been carried out in a three-stage batch system. All experiments have been conducted in a condition of alkalinity: 1.2.10(-2) eq/L, pH=9.5, T=25 degrees C, pO(2)=0.21 atm. According to the results, magnesium and calcium concentrations of 50 mg/L and above slowed down the oxidation of Mn(II), and nickel and zinc did not have any significant effect on oxidation. Similarly, it was found that gallic acid decelerated oxidation when tartaric acid did not have any important effect on oxidation.