优化内浸式Ce掺杂ZnO光催化降解罗丹明B

Optimization of internal immersed irradiation and photocatalytic degradation of rhodamine B with Ce doped ZnO particles

采用沉淀法优化制备了纳米级Ce掺杂ZnO,利用BET,XRD,SEM,ICP-AES,UV-VisDRS,FT-IR等手段对催化剂结构形态组成进行表征.提出内浸式光催化降解模式,考察液层厚度对透光率的影响,优化了Ce掺杂ZnO光催化降解罗丹明B实验条件,分析了其动力学和机理.结果表明,Ce掺杂比为3%(n:n),500℃热处理2h活性最高.催化剂呈球状,尺寸均匀,粒径80～100nm, BET比表面积12.9m^2/g,测定掺杂量和理论值一致, Ce掺杂增加了光吸收.悬浮液"遮挡效应"对光透过率衰减显著,催化剂浓度为0.1g/100mL时UV_(254)处光衰减率达到溶液的3倍.内浸式光催化降解1.0×10^(-5)mol/L罗丹明B溶液,在15W紫外灯,pH值为7,温度30℃,催化剂投加量0.1g/250mL条件下,70min降解率达到92.5%,6次套用降解率保持在80%以上,降解过程符合一级动力学,反应速率常数0.05min^(-1).

Cerium doped zinc oxide nano-scale particles was prepared by precipitation method, the properties including structure, morphology and composition were characterized by BET, XRD, SEM, ICP-AES, UV-Vis DRS and FT-IR. A new type of internal immersed irradiation photocatalytic degradation mode was proposed, relationship between liquid layer thickness and light transmittance was investigated. Finally, The conditions of photocatalytic degradation of rhodamine B were optimized, and the kinetics and mechanism were studied. Results showed that the optimum doped ratio and calcination temperature were 3%(n:n) and 500℃ for 2h, respectively. Catalyst particles was sphere appearance with an average diameter distribution of 80~100nm, and with BET specific surface area of 12.9m^2 /g, the content of doped cerium determined by ICP-AES accorded with theoretical value. The enhancement of catalytic activity was mainly due to the increase of light absorption after cerium doping. The shielding effect of suspension suggested a significant attenuation on light transmittance, light attenuation rate of UV 254 was twice more than that of homogeneous solution when the catalyst concentration was 0.1g/100mL. It was applied to rhodamine B with concentration of 1.0×10^-5 mol/L, the degradation rate reached to 92.5% in 70min when UV lamp power was 15W, pH value was 7, 30°C and catalyst dosage was 0.1g/250mL, and the degradation rate was up to 80% even after 6 recycle, it followed first-order kinetic equation and the reaction rate constant was 0.05min^-1 .