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Application of Pulsed Electrochemistry to Enhanced Water Decontamination
ACS ES&T Engineering Pub Date : 2021-09-09 , DOI: 10.1021/acsestengg.1c00141
Shuzhao Pei 1 , Shijie You 1 , Jinna Zhang 1
Affiliation  

In this study, we report the application of pulsed electrochemistry to enhanced water decontamination by electrochemical oxidation. By applying square current waveforms, the alternating pulse-on/-off operation results in periodic oscillation of anode potential, which is favorable for periodic renewal of electrical double layer (EDL) and alternant conditions for oxidation of organic pollutants. Under mass-transfer dominance at a current density of 20 mA cm–2, the rate constant for phenol oxidation under pulsed-current mode (PC, k = 1.48 h–1) is 52.5% higher than that under direct-current mode (DC, k = 0.97 h–1), accounting for a 57.1% decrease in energy consumption. In comparison with DC, PC does not change the pathway of phenol oxidation but is more selective for less accumulation of characteristic intermediates and efficient mineralization. The duty ratio and pulse period are shown to have a significant impact on the removal of chemical oxygen demand (COD), current efficiency, and energy consumption. The nonsteady diffusion models based on Fick’s second law illustrate that the transient local phenol concentration at the anode surface and limiting current density under PC condition are approximately 2.8 times that under DC, which provides a theoretical verification for the EDL-renewal mechanism of pulsed electrochemistry. This study suggests a simple, reliable, and economic route to enhance the performance of electrochemical oxidation, which can also be generalized to other kinds of electro-processes for water purification.

中文翻译:

脉冲电化学在强化水净化中的应用

在这项研究中,我们报告了脉冲电化学在通过电化学氧化增强水净化中的应用。通过施加方波电流波形,交替的脉冲开/关操作导致阳极电位的周期性振荡,这有利于双电层(EDL)的周期性更新和有机污染物氧化的交替条件。在电流密度为 20 mA cm –2 的传质优势下,脉冲电流模式 (PC, k = 1.48 h –1 )下苯酚氧化的速率常数比直流模式 (DC) 高 52.5% , k = 0.97 h –1),能耗下降 57.1%。与DC相比,PC不会改变苯酚氧化的途径,但对较少的特征中间体积累和有效矿化具有更高的选择性。显示占空比和脉冲周期对化学需氧量 (COD) 的去除、电流效率和能耗具有显着影响。基于Fick第二定律的非稳态扩散模型表明,PC条件下阳极表面的瞬态局部苯酚浓度和极限电流密度约为DC条件下的2.8倍,为脉冲电化学的EDL更新机制提供了理论验证。这项研究提出了一种简单、可靠且经济的途径来提高电化学氧化的性能,
更新日期:2021-11-12
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