元素掺杂材料在电催化反硝化中的研究进展

Progress in electrocatalytic denitrification using element-doped materials

电催化反硝化是处理硝酸盐废水技术之一。本文综述了电催化反硝化的最新研究进展,分析了电催化反硝化直接电子转移和原子氢(H)介导间接还原两种反应机理,总结了电催化反硝化的决速步是将NO-3还原为NO-2以及决定产物选择性的关键中间体是NO。在此基础上,总结了元素掺杂方法及其对电极材料催化活性中心和电催化反硝化反应路径的调控效应,提出了元素掺杂是提高电极材料催化活性、产物选择性和长期稳定性的有效手段。此外,还讨论了其他因素如水质特征、运行参数等对电催化反硝化效果的影响,明确了水中共存卤素离子如Cl-和Br-等可显著提高N 2选择性以及大多数电极材料在中性条件下还原效果最佳。面向日益增长的硝酸盐废水处理需求,指出了电能消耗高和实际废水水质成分复杂导致副反应多是限制电催化反硝化大规模应用的关键瓶颈。由此,展望了电催化反硝化技术研究未来需要针对多种实际废水的理化性质开展长期中试试验,除了提高还原速率和产物选择性外,还要重点关注电能消耗并对处理尾水的安全性进行监测,以促进电催化反硝化技术的进一步发展和实际应用。

Electrocatalytic denitrification is one of the promising technologies for the treatment of nitrate wastewater.This review comprehensively summarizes the recent advances in electrocatalytic denitrification.Two reaction mechanisms of direct electron transfer and atomic hydrogen(H)-mediated indirect reduction in electrocatalytic denitrification are analyzed.It is concluded that the rate-limiting step of electrocatalytic denitrification is the reduction of NO-3 to NO-2 and the key intermediate determining product selectivity is NO.On this basis,the element-doping method and its regulation effects on the catalytic active centers and the electrocatalytic denitrification pathways are summarized,and it is suggested that element doping is an effective method to improve the catalytic activity,product selectivity and long-term stability of electrode materials.In addition,the influence of other factors such as water quality characteristics and operating parameters on the electrocatalytic denitrification performance is discussed.It is confirmed that the coexistence of halogen ions in water,such as Cl-and Br-,can significantly improve the N 2 selectivity,and most electrode materials exhibit-the best performance under neutral conditions.Facing the increasing demand of nitrate wastewater treatment,it is pointed out that the key bottlenecks limiting the large-scale application of electrocatalytic denitrification are the high electric energy consumption and the complex composition of the actual wastewater which leads to side reactions.Therefore,it is expected that the future research of electrocatalytic denitrification technology needs to conduct long-term pilot-scale tests based on the physicochemical properties of various actual wastewater.In addition to improving the reduction rate and product selectivity,it is also necessary to pay attention to the electric energy consumption and monitor the safety of treated water to facilitate the further development and practical application of electrocatalytic denitrification technology.