Highly efficient total nitrogen and simultaneous total organic carbon removal for urine based on the photoelectrochemical cycle reaction of chlorine and hydroxyl radicals
Highly efficient total nitrogen and simultaneous total organic carbon removal for urine based on the photoelectrochemical cycle reaction of chlorine and hydroxyl radicals
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DOI：
10.1016/j.electacta.2018.11.087
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发表时间：
2019-02
影响因子：
6.6
通讯作者：
Z. Shen;Jinhua Li;Yan Zhang;Jing Bai;Xiaohan Tan;Xiaoyang Li;Li Qiao;Qunjie Xu;B. Zhou
中科院分区：
文献类型：
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作者：
Z. Shen;Jinhua Li;Yan Zhang;Jing Bai;Xiaohan Tan;Xiaoyang Li;Li Qiao;Qunjie Xu;B. Zhou
尿液是氮和COD的主要来源，对水环境构成威胁，导致富营养化和能源消耗。然而，由于尿液中氮和有机物的高负荷，传统的检测技术遇到了瓶颈。本文提出了一种在光电化学电池系统中利用氯和羟基自由基(Cl·点和HO·点)将尿素氮完全转化为N_2，并同时将有机物降解为CO_2的创新思路。这个想法揭示了这两个自由基的循环过程：在光照下，WO_3阳极氧化氯离子和羟基离子的光激空穴，这些自由基将尿素氮转化为N_2或少量硝酸盐，然后在新型Pd/Au修饰的多孔金属片上，少量硝酸盐被选择性地还原为N_2。对30 mg L−1模拟尿素溶液的TN分析表明，尿素的主要氧化产物为N_2和CO_2，90 分钟内尿素氮完全溶出(99.45%)。同时，通过对EPR谱的检测，发现在这个环状体系中，有机物可以被氧自由基团转化为二氧化碳。此外，还对实际尿液处理的可行性进行了考察，结果表明，该系统具有较高的脱氮效率(99.37%)和总有机碳(TOC)去除效率(50.91%)。这项工作揭示了一种经济、高效、环境友好的尿液污水处理新方法。
Urine is a major nitrogen and COD source and threatens the aqueous environment, leading to eutrophication and energy consumption. However, the conventional technologies encounter the bottleneck due to the high load of nitrogen and organics in urine. Here we propose an innovative idea for complete transformation of urea-nitrogen to N2and simultaneous degradation of organics to CO2with the assistance of chlorine and hydroxyls radicals (Clradical dotand HOradical dot) in photoelectrochemical cell system. This idea reveals circulation process of these two radicals: photoexcited holes from WO3anode oxidize chloride and hydroxyl ions to Clradical dotand HOradical dotradicals under illumination, these radicals convert urea-nitrogen to N2or slight nitrate, and then slight nitrate is selectively reduced to N2on a novel Pd/Au modified porous metallic sheet. TN analysis of a simulated urea solution of 30 mg L−1demonstrated that N2and CO2are the primary oxidation products of the urea, and the urea-N was completely stripped (99.45%) in 90 min. Meanwhile, with the detection of EPR spectrum, organics can be transformed to CO2by OHradical dotin this cyclic system. Significantly, the feasibility of actual urine treatment was also investigated, indicating great denitrification efficiency (99.37%) and TOC removal efficiency (50.91%), respectively. This work sheds light upon a new economical, efficient, and environment-friendly means of urine sewage treatment.