g-C_3N_4光催化降解2,4-DCP的活性及机理  

Activity and mechanism of photocatalytic degradation for 2,4-DCP over g-C_3N_4

作　　者：吴斌[1,2,3] 方艳芬[2,3] 任慧君[1,2,3] 赵萍[2,3] 黄应平[1,2,3] 

机构地区：[1]三峡大学水利与环境学院,宜昌443002 [2]三峡库区生态环境教育部工程研究中心(三峡大学),宜昌443002 [3]三峡地区地质灾害与生态环境湖北省协同创新中心(三峡大学),宜昌443002

出　　处：《环境化学》2017年第7期1484-1491,共8页Environmental Chemistry

基　　金：国家自然科学基金(21377067;21677086;21577078);湖北省创新群体项目(2015CFA021);国家水专项子课题(2012ZX07104-003-04)资助~~

摘　　要：以三聚氰胺(Melamine)为原料,在高温条件下采用热缩合反应合成了石墨型氮化碳(g-C_3N_4)光催化剂.通过X-射线衍射(XRD)、扫描电镜(SEM)、紫外-可见漫反射光谱(UV-Vis DRS)、衰减全反射红外光谱(ATR-IR)等技术对其物理结构及性质进行了表征,结果表明实验制备的g-C_3N_4为片层状结构,比表面积为15.34 m^2·g^(-1).在可见光(λ>420 nm)照射下,用g-C_3N_4降解有机小分子污染物2,4-二氯苯酚(2,4-Dichlorophenol,2,4-DCP),该过程反应符合一级动力学,反应速率常数为0.0113 min^(-1),以0.67 g·L^(-1)的用量反应250 min后2,4-DCP矿化率达到60%;2,4-DCP在弱酸性条件下(p H=5.4)的降解效率最高;通过捕获实验及电子自旋共振(ESR)实验表明,超氧自由基(O·-2)是g-C_3N_4光催化降解2,4-DCP过程中的主要活性物种.2,4-DCP的降解路径主要涉及脱氯、苯环开环和碳链断裂等反应历程.Graphite carbon nitride （g-C3N4） photocatalyst was synthesized via thermal condensation at high temperatures using melamine as a starting material. The structure and properties of the catalyst was characterized by scanning electron microscopy （SEM）,X-ray diffraction （XRD）,UV-Vis diffuse reflectance spectroscopy （UV-Vis DRS）, and attenuated total reflection infrared spectroscopy （ATR-IR）.The results indicate that the as-synthesized g-C3N4 had a layered structure with a specific surface area of 15.34 m2·g-1 and possed strong visible light absorption capacity. Photocatalytic degradation of 2,4-dichlorophenol （2,4-DCP） using g-C3N4 under visible light irradiation （λ〉420 nm） corresponds to the first order kinetics with a reaction rate constant of 0.0113 min-1.After 250 min,the mineralization rate of 2,4-DCP in the presence of 0.67 g·L-1g-C3N4 reached 60%. The degradation efficiency of 2,4-DCP was highly enhanced in weak acid. Trapping experiments and electron spin resonance （ESR） experiments show that superoxide radical （O2·-） was the main active species in the photocatalytic degradation of 2,4-DCP.The main degradation pathways of 2,4-DCP include dechlorination,aromatic ring opening and carbon chain rupture.

关 键 词：石墨型氮化碳 2 4-二氯苯酚 光催化降解 

分 类 号：O643.36[理学—物理化学] X592[理学—化学]