In Situ Photochemical Activation of Sulfate for Enhanced Degradation of Organic Pollutants in Water
In Situ Photochemical Activation of Sulfate for Enhanced Degradation of Organic Pollutants in Water
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原位光化学活化硫酸盐增强水中有机污染物的降解
DOI：
10.1021/acs.est.6b05090
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发表时间：
2017-02-21
影响因子：
11.4
通讯作者：
Ren, Nanqi
中科院分区：
文献类型：
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作者：
Liu, Guoshuai;You, Shijie;Ren, Nanqi
基于SO4中心点自由基的高级氧化法(AOP)在水处理中受到越来越多的关注。过一硫酸盐或过硫酸盐活化生产SO4中心点自由基面临着操作成本高和潜在的二次污染的挑战。在本研究中，我们报道了以磷酸铋(BPO)为光催化剂，硫酸盐(i-PCAS)原位光化学活化生成SO4中心点自由基。在pH中性条件下，硫酸盐对2，4-二氯苯酚(2，4-DCP)的降解效果显著，其一级动力学常数(k=0.0402 m in‘)约为无硫酸盐(k=0.019 m in(-1))时的2.1倍。这与商品二氧化钛(P25)形成了鲜明的对比，后者的性能总是受到硫酸盐的抑制。自由基清除剂和电解液的影响，结合电子自旋共振(ESR)测量，证实了I-PCAS过程中形成了中心点OH和SO4中心点自由基。根据理论计算，BPO具有足够高的价带势，在热力学上有利于硫酸盐的氧化，并且与SO4中心点自由基的相互作用较弱，对目标有机污染物具有较高的反应活性。I-PCAS的概念在建立新的光化学体系方面似乎很有吸引力，在这些体系中，最初存在于水环境中的硫酸盐可以实现原位产生SO4中心点自由基。这消除了对外部化学物质和pH调节的需要，使水处理变得更加容易、更经济和更可持续。
The advanced oxidation process (AOP) based on SO4 center dot- radicals has been receiving growing attention in water and wastewater treatment. Producing SO4 center dot- radicals by activation of peroxymonosulfate or persulfate faces the challenges of high operational cost and potential secondary pollution. In this study, we report the in situ photochemical activation of sulfate (i-PCAS) to produce SO4 center dot- radicals with bismuth phosphate (BPO) serving as photocatalyst. The prepared BPO rod-like material could achieve remarkably enhanced degradation of 2,4-dichlorophenol (2,4-DCP) in the presence of sulfate, indicated by the first-order kinetic constant (k = 0.0402 min') being approximately 2.1 times that in the absence (k = 0.019 min(-1)) at pH-neutral condition. This presented a marked contrast with commercial TiO2 (P25), the performance of which was always inhibited by sulfate. The impact of radical scavenger and electrolyte, combined with electron spin resonance (ESR) measurement, verified the formation of center dot OH and SO4 center dot- radicals during i-PCAS process. According to theoretical calculations, BPO has a sufficiently high valence band potential making it thermodynamically favorable for sulfate oxidation, and weaker interaction with SO4 center dot- radicals resulting in higher reactivity toward target organic pollutant. The concept of i-PCAS appears to be attractive for creating new photochemical systems where in situ production of SO4 center dot- radicals can be realized by using sulfate originally existing in aqueous environment. This eliminates the need for extrinsic chemicals and pH adjustment, which makes water treatment much easier, more economical, and more sustainable.