NO3− photolysis-induced advanced reduction process removes NO3− and 2, 4, 6-tribromophenol

Abstract

Reductive processes are an important type of pollutant removal technology, particularly for organic halogens. NO3− is an anion and pollutant that is commonly present in wastewater. In this study, a novel advanced reduction process (ARP) induced by NO3− photolysis was developed to remove 2,4,6-tribromophenol (TBP) and NO3−. The UV/NO3−/formate acid (FA) process achieved NO3− removal and improved the debromination of TBP (initial TBP concentration = 0.1 mM) (up to 97.8%), however, their coexistence adversely affected the reductive removal of each component. Acidic conditions (pH 3 in this study) benefited the removal of NO3− and the debromination of TBP. Cl− promoted NO3− removal in UV/NO3−/FA, however, it decreased the debromination effect of TBP by 27.8%. Humic acid, a typical dissolved organic matter, suppressed NO3− removal, TBP degradation and debromination under all experimental conditions. Methyl viologen significantly inhibited the performance of ARP, and this verified the role of CO2•- in this ARP. Insufficient reduction and over-reduction of NO3− were observed under different conditions and a greater amount of NH4+ was formed under the influence of TBP. The data also indicated that as much as 80% of the removed NO3− was converted to NO2−, and this is noteworthy. Due to the reductive radicals generated from the oxidation of FA, both oxidative and reductive products of TBP were detected in the effluent. The results of this study provide a potential technology for the reductive removal of organic halogens from NO3−-rich wastewater.