National Engineering Research Center for Industry Crystallization Technology,School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
National Engineering Research Center for Industry Crystallization Technology,School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China; Co-Innovation Center of Chemical Science and Engineering, Tianjin, 300072, China.
Chemosphere. 2021 Sep;278:130386. doi: 10.1016/j.chemosphere.2021.130386. Epub 2021 Mar 29.
Excessive nitrate in industrial wastewater is still an important environmental protection issue for human beings. As nitrate promoter metal, Sn has been extensively studied in nitrate reduction reaction (NITRR). However, it suffers from high selectivity of nitrite as the final product at times. As the same main group as Sn, bismuth-based materials have exhibited excellent performance in the field of electrochemical reduction reactions but were rarely investigated for NITRR. In this study, BiO nanosheets in-situ decorated on carbon cloth (BiO-CC) was synthesized and it showed larger surface area and higher electrical conductivity than those of dropped BiO nanosheets onto carbon cloth (BiO/CC). Experimental results show that the nitrate removal efficiency of BiO-CC increased by 12.7% than that of BiO/CC at the same condition. Besides, the presence of Cl benefits the NITRR process since the reaction of BiO and Cl in acidic conditions can accelerate the conversion of Bi to Bi. The mechanism of the NITRR process was proposed based on the electrochemical and scavenging experiments. It was found that both the direct electron transfer and atomic H∗ contribute to the electrochemical reduction of nitrate to ammonia. More importantly, when BiO-CC was applied to actual garbage fly ash wastewater, most nitrates were converted to ammonia. The designed BiO-CC is a high-potential material for converting nitrate in industrial wastewater to valuable feedstock chemical ammonia with high efficiency.
工业废水中过量的硝酸盐仍然是人类环境保护的一个重要问题。作为硝酸盐促进金属，锡在硝酸盐还原反应（NITRR）中得到了广泛的研究。然而，它有时会受到亚硝酸盐作为最终产物的高选择性的影响。作为与锡同主族的铋基材料，在电化学还原反应领域表现出了优异的性能，但在 NITRR 方面的研究却很少。在本研究中，合成了原位修饰在碳布上的 BiO 纳米片（BiO-CC），与负载在碳布上的 BiO 纳米片（BiO/CC）相比，它具有更大的比表面积和更高的电导率。实验结果表明，在相同条件下，BiO-CC 的硝酸盐去除效率比 BiO/CC 提高了 12.7%。此外，Cl 的存在有利于 NITRR 过程，因为 BiO 和 Cl 在酸性条件下的反应可以加速 Bi 向 Bi 的转化。基于电化学和清除实验提出了 NITRR 过程的机理。研究发现，直接电子转移和原子 H∗都有助于硝酸盐电化学还原为氨。更重要的是，当 BiO-CC 应用于实际垃圾飞灰废水中时，大部分硝酸盐都转化为氨。设计的 BiO-CC 是一种将工业废水中的硝酸盐高效转化为有价值的饲料化学氨的高潜力材料。
