Reductive catalysis of novel TiO2/Fe0 composite under UV irradiation for nitrate removal from aqueous solution

Groundwater contaminated by nitrate has become a worldwide problem. Existing technologies for nitrate removal, including zero-valent iron reduction, can only transform nitrate ions to predominantly NH4+. As a result, many studies have concentrated on seeking a solution to convert nitrate to N2. In this study, the efficiencies of nitrate removal from aqueous solution by single (TiO2 and nano zero valent iron, nZVI), and composite (Nano-TiO2–Fe0 composite, NTFC) system under UV illumination were prepared. Among the three systems, both nZVI and NTFC can effectively remove nitrate. However, only NTFC can achieve satisfactory transformation of nitrate to N2. Further investigation has proven that the composition of NTFC (TiO2/nZVI ratio) greatly influences the conversion of nitrate to N2, which can be attributed to the maintenance of high level of ferrous ions in the NTFC system due to its reducing condition.

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► NTFC is more efficient in nitrate degradation than the nZVI.
► NTFC system is in reducing condition (low ORP), in which large quantity of ferrous ions can be maintained.
► NTFC can achieve satisfactory transformation of nitrate to N2.
► The best performance of NTFC is achieved when the TiO2 to nZVI ratio of the NTFC composite is 1 to 10.