Application of vacuum-ultraviolet (VUV) for phenolic homologues removal in humic acid solution: Efficiency, pathway and DFT calculation
Application of vacuum-ultraviolet (VUV) for phenolic homologues removal in humic acid solution: Efficiency, pathway and DFT calculation
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DOI：
10.1016/j.jhazmat.2019.121464
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发表时间：
2020-02-15
影响因子：
13.6
通讯作者：
Cui Chong-wei
中科院分区：
文献类型：
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作者：
Cao Ting-ting;Xu Tie-fu;Cui Chong-wei
研究了苯酚类同质物在模拟天然水中的真空紫外（VUV）光引发氧化反应，包括苯酚、邻二酚（ODB）、间二酚（MDB）、对二酚（PDB）、副硝基酚（PNP）和邻氯酚（OCP）。结果表明，酚类同系物在纯水中的去除率可达90%以上，其去除率与温度、pH、HA浓度和HA官能团有关。实验结果表明0.2 mg/L HA可能是一个临界点。此外，6种酚类同源物在MDB溶液中的速率常数分别比纯水中的速率常数降低76.85%、77.81%、71.91%、79.15%和55.69%，在苯甲酸（BA）溶液中的速率常数分别比纯水中的速率常数降低79.73%、82.80%、95.36%、80.38%和92.64%。此外，量子化学计算表明，酚类化合物之间的去除率差异归因于苯环上的取代基。HA的羧基在一定程度上抑制了酚类同系物的去除率。总结了真空紫外（VUV）降解酚类同质物的机理，其中经过醌结构的形成、开环、短链有机酸的形成，甚至最终转化为PNP和OCP的NO3-和Cl-。
Vacuum-ultraviolet (VUV) photo-initiated oxidation of phenolic homologues in simulative natural water were investigated, including phenol, o-dihydroxybenzene (ODB), m-dihydroxybenzene (MDB), p-dihydroxybenzene (PDB), paranitrophenol (PNP) and o-chlorophenol (OCP). Results showed the phenolic homologues removal rate reached at least 90% in pure water, which was dependent on temperature, pH, concentration of HA, and functional group of HA. Experimental results indicated that 0.2 mg/L HA might be a critical point. Additionally, the rate constant of the six phenolic homologues reduced by 76.85%, 77.81%, 71.91%, 79.15%, and 55.69%, respectively in the MDB solution, and 79.73%, 82.80%, 95.36%, 80.38%, and 92.64%, respectively in the benzoic acid (BA) solution, compared to the rate constant in pure water. Moreover, quantum chemistry calculation indicated that the variances between phenolic compounds in removal rate were attributed to the substituent on the benzene ring. And, to some extent, the carboxy group of HA was supposed to arose the suppression for phenolic homologues removal rate. Mechanism involved phenolic homologues degradation using vacuum-ultraviolet (VUV) was summarized, where it underwent the formation of quinone structures, ring opening, short-chain organic acid, even eventually the transformation into NO3- and Cl- of PNP and OCP.