在Cr(Ⅵ)和4-氯酚复合污染系统中多孔石墨相氮化碳的协同光催化效应（英文）.doc

在Cr(VI)和4-氯酚复合污染系统中多 孔石墨相氮化碳的协同光催化效应(英 文)魏凯李可心曾振兴戴玉华颜流水郭会琴罗旭 彪南昌航空大学江西省持久性污染物控制与资源循环利用重点实验室摘要：随着工农业的迅速发展，多组分复合污染系统广泛分布于自然环境中，例如电 镀废水、污水处理厂污泥、城市生活垃圾等.自1972年光催化劈裂水产氢被发现 以来，光催化技术己被广泛应用于解决环境污染问题.一方面，光生电子在酸性 条件下能将重铬酸根(Cr2O广)中高毒性的Cr (VI)还原成低毒性的Cr (III). 另一方面，水中有机污染物通过光催化氧化过程可被降解为二氧化碳和水.然而 在目前的光催化领域，大部分研宂荞专注于新型光催化剂的开发，并在单组份 光催化系统中测试所开发材料的光催化活性，而忽视了蕴藏在光催化反应本身 中的科学问题.事实上，将光催化技术应用于复合污染系统具有非常大的现实意 义.少数研究者试图通过光催化过程处理多组分废水.然而，在复合污染系统中 的协同光催化效应和机理尚未明确.近几年，基于可见光响应、环境友好、成本 低等优点，作为一种不含金属的半导体光催化剂，石墨相氮化碳(g_C况)已被 广泛应用于环境光催化领域.然而在实际应用中，g_C凡的光催化活性却较差，因为聚集态层状结构不但限制了光生载流子的表面迁移，而且还增加了光催化 反应的传质阻力.因此，人们尝试形貌控制策略来提高g_C3N4的光催化活性，例 如氮化碳纳米片、空心球、量子点的构建.在前期工作中，我们通过一种简单的 前驱体预处理策略使用盐酸和乙二醇共处理的三聚氰胺作原料成功制备出了多 孔石墨相氮化碳(pg_C3Nj，因其具有丰富的多孔微观结构而表现出了卓越的 光催化活性.木文初步研究了在酸性条件下使用所制备g_C3N4或Pg-C3N4光催化还 原水中Cr (VI)成Cr (III)的反疲.然后在不同p H条件下进一步研究了在Cr (VI)和4-氯酚(4-CP)复合污染系统中的协同光催化效应.结果发现，与单组 分光催化系统相比，在Cr(VI)和4-CP复合污染系统中Cr (VI)的还原效率和 4-CP的降解效率同时提高，即在Cr(VI)和4-CP复合污染系统中存在协同光催 化效应.最后讨论了在Cr (VI)和4-CP复合污染系统中的协同光催化效应可归 因于pg_C3N4的电子转移作用加速了 Cr2O广和4-CP之间的氧化还原反应.在用稀 H2SO4调节p n至3的Cr (VI)和4-CP复合污染系统中,由于Cr2O广中氧原子的电子云密度较低，因此Cr2072’和4-CP之间的氧化还原反应通过pg-C具的电子转 移作用易于进行，因而表现出明显的协同光催化效应.关键词：复合污染;协同光催化作用;多孔石墨相氮化碳;Cr (VI) ; 4-氯酚;作者简介：李可心/：(0791) 83953373;电子信箱：likx880@hotmail. com作者简介：戴玉华/:(0791) 83953373;电子信箱：dyh-8808@收稿日期：28 June 2017基金：supported by the National Natural Science Foundation of China (51568049, 51468043, 21366024, 21665018)Synergistic photocatalytic effect of porous g-C3N4 in a Cr (VI)/4-chlorophenol composite pollution systemKai Wei Kexin Li Zhenxing Zeng Yuhua Dai Liushui Yan Huiqin Guo Xubiao LuoKey Laboratory of Jiangxi Province forPersistent Pollutants Control and ResourcesRecycle， Nanchang Hangkong University;Abstract：The photocatalytic reduction of aqueous Cr (VI) to Cr (III) was preliminarily studied using porous g-C3N4 as a photocatalyst under acidic conditions. The observed synergistic photocatalytic effect of porous g-C3N4 on a Cr (VI) /4-chlorophenol (4-CP) composite pollution system was further studied under different pH conditions. Compared with single-component photocatalytic systems for Cr (VI) reduction or 4-CP degradation, the Cr (VI) reduction efficiency and 4-CP degradation efficiency were simultaneously improved in the Cr (VI) /4-CP composite pollution system. The synergistic photocatalytic effect in the Cr (VI) /4-CP composite pollution system can be attributed to the accelerated redox reaction between dichromate and 4-CP by electron transfer with porous g-C3N4.Keyword：Composite pol lution; Synergistic photocatalysis; Porous g~C3N4; Cr (VI); 4-Chlorophenol;Received： 28 June 20171. IntroductionMulti-component composite pollution systems, such as electroplating wastewater, sludge in polluted water treatment plants, and urban refuse, are widely distributed in nature due to the rapid development of industry and agriculture[l - 3]. Since photocatalytic hydrogen production from water splitting was discovered in 1972， photocatalytic technology has been widely used to remove environmental pol 1 ution[4 - 6]• Photogenerated electrons can reduce highly toxic hexavalent chromium (Cr (VI) ) in aqueous dichromate (Cr2072 -) to low-toxicity trivalent chromium (Cr (III) ) under acidic conditions[7]. Furthermore, aqueous organic pollutants can be degraded to carbon dioxide and water by photocatalytic oxidation processes[8]. However, in the current field of photocatalysis, most research is focused on developing novel photocatalysts and determining their photocatalytic activities in single-component photocatalytic systems, with scientific issues inherent to the photocatalytic reaction itself often ignored[9 - 11]. In fact, the application of photocatalytic technology to composite pollution systems has great practical significance. A few researchers have attempted to treat multi-component wastewater using photocatalytic processes[12， 13]. However, synergistic photocatalytic effects and mechanisms in composite pollution systems have not been clarified.Tn recent years, graphitic carbon nitride (g-C3N.i) has been widely applied as a mctal-frcc semiconductor photocatalyst in the field of environmental photocatalysis due to its advantages, including visible-light response, environmental friendliness, and low cost[14 - 21]. However, the photocatalytic activity of g-C3N,i is poor in practical applications due to its bulk layered structure, which limits the surface migration of photogenerated carriers and increases mass transfer resistance in the photocatalytic reaction. Therefore, some researchers have improved the photocatalytic activity of g-C3N4 using morphology control strategies, such as constructing carbon nitride nanosheets, hoi low spheres, and quantum dots[22 - 24]• In our previous study, porous g-C3N4 was successfully fabricated via a simple precursor pretreatment strategy using melamine co-pretreated with HC1 and ethylene glycol (EG) as a raw material [25, 26]. The as-prepared porous g-C3N4 showed。