Dawson型磷钨酸季铵盐对亚甲基蓝废水的光催化降解

Photocatalytic Degradation of Methylene Blue Using the New Quaternary Ammonium Salt Based on Dawson-type Phosphotungstate Acid

采用共沉淀法制备了一种新的Dawson型磷钨酸十二烷基三甲基铵盐[C_(15)H_(34)N]_(6)P_(2)W_(18)O_(62)·2H_(2)O,通过红外光谱、热重分析、EDS能谱和扫描电镜对其组成、结构及形貌进行了表征,采用BET氮气吸附测定了比表面积。以亚甲基蓝为模拟染料废水,研究其光催化性能和降解亚甲基蓝的动力学行为,研究结果表明:14 mg/L的50 mL亚甲基蓝模拟染料废水在pH为4的条件下,加入20 mg催化剂,35 W紫外灯光照2 h,亚甲基蓝降解率达到95.0%,光催化降解反应符合一级动力学模型,动力学方程为:lnρ0/ρt=0.051 7t,降解速率常数为0.051 7 min-1,半衰期为13.4 min,表明Dawson型磷钨酸十二烷基三甲基铵对亚甲基蓝的降解具有高效的光催化活性,且重复使用催化性能好,循环5次后的降解率达到94.53%。

A new Long carbon-chain quaternary ammonium salt[C_(15)H_(34)N]_(6)P_(2)W_(18)O_(62)·2H_(2)O based on Dawson type phosphotungstate acid was prepared by using coprecipitation method.IR,TG,EDS and SEM were employed to characterize the composition,structure and morphology of the compound.The specific surface area was determined by BET nitrogen adsorption.Using methylene blue as a simulated dye wastewater,the photocatalytic properties and the kinetic behavior of degradation of methylene blue were investigated.The results showed that the degradation rate of methylene blue reached 95.0%at conditions of pH=4,the initial concentration of 14 mg/L of 50 mL methylene blue dye wastewater,the catalyst dosage of 20 mg,illuminating for 2 h under the 35 W UV lamp light.The photocatalytic degradation reaction fits with a first-order kinetic model,the kinetic equation is lnρ0/ρt=0.0517t,degradation rate constants is 0.0517 min^(-1),half-life is 13.4 min,which shows that the catalyst has a highly efficient photocatalytic activity against the methylene blue degradation.The recycle experiments showed that the catalyst has good reusability,and the degradation rate of methylene blue reached 94.53%after 5 cycles.