School of Urban Construction, Wuhan University of Science and Technology, Wuhan, 430065, People's Republic of China.
Institute of High Performance Engineering Structure, Wuhan University of Science and Technology, Wuhan, 430065, People's Republic of China.
Environ Sci Pollut Res Int. 2023 Feb;30(7):17854-17864. doi: 10.1007/s11356-022-23364-3. Epub 2022 Oct 6.
The decay of free radicals involved in side reactions is one of the challenges faced by electrochemical degradation of organic pollutants. To this end, a non-radical oxidation system was constructed by a natural air diffusion cathode (ADC) and a Ti-based dimensional stable anode coated by RuO (RuO-Ti anode) for cathodic hydrogen peroxide activation by anodic chlorine evolution. The ADC fabricated by the carbon black of BP2000 produced a stable concentration of hydrogen peroxide of 339.94 mg L (current efficiency of 73.4%) without aeration, which was superior to the cathode made by the XC72 carbon black. The flow-by ADC-RuO system consisted of an ADC and a RuO-Ti anode showed high selectivity to aniline (AN) compared to benzoate (BA) in a NaCl electrolyte, whose degradation efficiencies were 97.72% and 1.3%, respectively. Rapid degradations of a mixture of emerging pollutants and AN were also observed in the ADC-RuO system, with pseudo-first-order kinetic constants of 0.51, 1.29, 0.89, and 0.99 min for Bisphenol A (BPA), tetracycline (TC), sulfamethoxazole (SMX) and AN, respectively. Quenching experiments revealed the main reactive oxygen species for the pollutant degradation was singlet oxygen (O), which was also identified by the electron spin resonance (ESR) analysis. Finally, the steady-stable content of O was quantitatively determined to be 6.25 × 10 M by the method of furfuryl alcohol (FFA) probe. Our findings provide a fast, low energy consumption and well controlled electrochemical oxidation method for selective degradation of organic pollutants. HO generated on an air diffusion cathode by naturally diffused O, reacts with ClO produced from chloride oxidation on the RuO-Ti anode to form singlet oxygen (O). The electrochemical system shows an efficient oxidation to electron-rich emerging pollutants including bisphenol A, tetracycline, sulfamethoxazole and aniline, but a poor performance on the electron-deficient compounds (e.g., benzoate).
自由基的衰减是有机污染物电化学降解面临的挑战之一。为此，构建了一种非自由基氧化体系，该体系由自然空气扩散阴极（ADC）和涂覆 RuO 的钛基尺寸稳定阳极（RuO-Ti 阳极）组成，用于通过阳极氯氧化产生阴极过氧化氢的激活。由 BP2000 炭黑制造的 ADC 无需曝气即可产生稳定浓度的 339.94mg L 的过氧化氢（电流效率为 73.4%），优于 XC72 炭黑制成的阴极。在 NaCl 电解质中，与苯甲酸盐（BA）相比，由 ADC 和 RuO-Ti 阳极组成的流动 ADC-RuO 体系对苯胺（AN）具有高选择性，其降解效率分别为 97.72%和 1.3%。在 ADC-RuO 体系中，还观察到新兴污染物和 AN 的混合物的快速降解，其伪一级动力学常数分别为 0.51、1.29、0.89 和 0.99 min，对于双酚 A（BPA）、四环素（TC）、磺胺甲恶唑（SMX）和 AN。猝灭实验表明，污染物降解的主要活性氧物质是单线态氧（O），这也通过电子自旋共振（ESR）分析得到了证实。最后，通过糠醇（FFA）探针法定量测定了 O 的稳定含量为 6.25×10-5M。我们的研究结果为选择性降解有机污染物提供了一种快速、低能耗和可控的电化学氧化方法。在自然扩散的 O 的作用下，在空气扩散阴极上生成的 HO 与 RuO-Ti 阳极上氯化物氧化产生的 ClO 反应生成单线态氧（O）。电化学体系对富电子新兴污染物（包括双酚 A、四环素、磺胺甲恶唑和苯胺）具有高效氧化作用，但对缺电子化合物（如苯甲酸盐）的性能较差。
