Selective and Efficient Reduction of Nitrate to Gaseous Nitrogen from Drinking Water Source by UV/Oxalic Acid/Ferric Iron Systems: Effectiveness and Mechanisms

Nitrate (NO3−) reduction in water has been receiving increasing attention treatment due to its carcinogenic and endocrine-disrupting properties. This study employs a novel advanced process, the UV/oxalic acid/ferric iron systems (UV/C2O42−/Fe3+ systems), reducing NO3− high efficiency, excellent selectivity, low cost. The UV/C2O42−/Fe3+ process reduced with pseudo-first-order reaction rate constants of 0.0150 ± 0.0013 min−1, minimizing 91.4% 60 mg/L reaching 84.2% selectivity for gaseous nitrogen after 180 min at pHini. 7.0 0.5 dissolved oxygen (DO). Carbon dioxide radical anion (CO2•−) played predominant role NO3−. Gaseous NH4+, as well CO2, were main nitrogen- carbon-containing products, respectively, pathways proposed accordingly. A suitable level oxalic acids (3 mM) (60 mg/L) was recommended; initial concentrations UV intensity increased reduction. Instead, solution pH decreased reduction, 0.5–8.0 DO negligibly affected process. Moreover, not retarded by 0.1–10 mM SO42− or Cl− 0.1–1.0 HCO3− but prohibited 10 30 mg-C/L humic acids. There lower simulated groundwater (72.8%) than deionized DO, which meets drinking standard (<10 N-NO3−). Therefore, are promising approaches selectively efficiently reduce water.