A facile VUV/H2O system without auxiliary substances for efficient degradation of gaseous toluene
A facile VUV/H2O system without auxiliary substances for efficient degradation of gaseous toluene
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DOI：
10.1016/j.cej.2017.11.056
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发表时间：
2018-02
影响因子：
15.1
通讯作者：
Yujie Zhan;Jian Ji;Haibao Huang;M. He;D. Leung;Shuilian Liu;Yajie Shu;Qiuyu Feng;R. Xie;Ruimei Fang;Xinguo Ye
中科院分区：
文献类型：
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作者：
Yujie Zhan;Jian Ji;Haibao Huang;M. He;D. Leung;Shuilian Liu;Yajie Shu;Qiuyu Feng;R. Xie;Ruimei Fang;Xinguo Ye
催化氧化和高级氧化工艺通常在VOCs降解过程中需要催化剂或化学氧化剂，这使得这些工艺成本高且复杂。本文开发了一种简便的VUV/H2O系统，用于在不添加辅助物质的情况下高效降解VOCs。通过对甲苯降解反应条件的控制、中间产物的检测和反应过程的分析，对该体系的性能和机理进行了深入研究。与直接真空紫外光降解气相甲苯（VUV/Gas）相比，VUV/H2O系统对鼓泡进入系统的甲苯具有更高的去除率（83%）和矿化率（80%）。此外，在出口气流中没有检测到O3和气态副产物。VUV/H2O的优异性能归因于水的VUV光解产生更多的·OH和溶解在水中的累积中间产物的持续降解。在空气气氛下的高CO2产率表明，水中的溶解氧是必不可少的甲苯矿化，因为它参与了环断裂的甲苯。根据检测到的各种自由基和有机中间体，提出了甲苯在VUV/H2O体系中降解的可能途径，包括OH加成、夺氢和异构化。反应后的水可以通过持续的VUV照射来有效地净化。本研究提出了一种不含辅助物质的VUV/H2O体系，并对其降解机理进行了深入研究。
Catalytic oxidation and AOPs normally require catalysts or chemical oxidants during VOCs degradation, making these processes costly and complex. We herein developed a facile system, VUV photolysis in pure water (VUV/H2O), for efficient VOCs degradation without auxiliary substances. The performance and mechanism of this system was intensively studied through controlling reaction conditions, detecting intermediates and analyzing reaction process during toluene degradation. Compared with direct VUV photolysis of gaseous toluene (VUV/Gas), the VUV/H2O system exhibited higher removal efficiency (83%) and mineralization rate (80%) of gaseous toluene bubbled into the system. In addition, no O3and gaseous byproducts were detected in the outlet gas stream. The excellent performance of VUV/H2O was attributed to the generation of more ·OH from the VUV photolysis of water and the continuous degradation of accumulated intermediates dissolved in water. The high CO2yield under an air atmosphere demonstrated that the dissolved oxygen in the water was essential for toluene mineralization since it was involved in the ring-fragmentation of toluene. According to various radicals and organic intermediates detected, possible pathway of toluene degradation in the VUV/H2O system was also proposed, which include OH addition, hydrogen abstraction and isomerization. The water after reaction can be effectively purified by sustaining VUV irradiation. This study presents a facile VUV/H2O system without auxiliary substances for efficient VOCs degradation and provides an insight into its degradation mechanism.