中文摘要：

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-C3N4）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-C3N4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-C3N4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-C3N4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.

英文摘要：

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.