煅烧温度对纳米 SnO2光催化降解亚甲基蓝的影响

摘要

采用四氯化锡与氢氧化钠在92℃下直接沉淀法制备了纳米级SnO2，经不同温度处理得到性质不同的SnO2样品．研究了处理温度对SnO2性质和紫外光（254 nm）照射下降解亚甲基蓝（MB）效率的影响．结果显示：200℃处理样品的降解率最高，超过该温度后，随着处理温度的升高，SnO2的粒径逐渐增大，比表面依次减小，表面吸附的羟基或水的数量减少，则样品的降解率逐渐减小．SnO2降解MB的反应为拟一级反应，满足Langmuir-Hinshelwood 模型，且在UV/SnO2降解体系中，羟自由基OH·为主要的活性体，它与MB反应导致其最终分解为CO2、H2 O和无机酸根离子等无害物质．%The nano-SnO2 was synthesized by direct precipitation of tin tetrachloride ( SnCl4 ) and sodium hydroxide ( NaOH) at 92 ℃and a series of SnO 2 samples with different characters were obtained by calcined at different tem-peratures .The effects of calcination temperature on characters of SnO 2 and photodegradation of methylene blue ( MB) under UV-light (254 nm) irradiation have been investigated .The SnO2 sample calcined at 200 ℃showed the highest MB degradation rate .When the calcination temperature is over 200℃, with increasing calcination tem-perature the particle size of SnO 2 increases and the specific area of SnO 2 decreased , so the degradation rates of MB are decreased .The photocatalytic degradation kinetics was analyzed in detail , which fits a pseudo-first-order kinet-ics and the Langmuir-Hinshelwood model .In UV/SnO2 system the hydroxyl radical OH · play a critical role in the degradation of MB , inducing the complete mineralization of MB to carbon dioxide , water and mineral acid .