Reaction mechanism and selectivity regulation of photocatalytic nitrate reduction for wastewater purification: progress and challenges

The excess emission of nitrate into wastewater is inevitable by the abundant use of fertilizers and other chemicals, which poses a huge threat to the environment and human health. Photocatalytic nitrate reduction is regarded as a promising strategy to remove nitrate on account of the high efficiency, low energy consumption and wide applicability. In this review, the mechanism of photocatalytic nitrate reduction is summarized, especially the generation and transformation mechanism of the reactive species and intermediate products is concluded. Then the methods for investigating and regulating selectivity for innocent nitrogen production from nitrate reduction are proposed. At last, the challenges and outlooks of photocatalytic nitrate reduction are put forward as a near-future technology. The excess emission of nitrate into wastewater is inevitable by the abundant use of fertilizers and other chemicals, which poses a huge threat to the environment and human health.