微波诱导水解法制备纳米TiO_2及光催化降解盐酸四环素

采用微波诱导水解法快速制备了纳米TiO_2光催化剂,通过XRD、TEM、SEM、BET和EDS技术对其进行了表征。该方法可在10 min内制备出平均粒径约7.5 nm的锐钛矿相纳米TiO_2。采用该催化剂(加入量0.5 g/L)对盐酸四环素(TC,100 mg/L)进行紫外光催化降解,40 min时降解率高达92.9%,60 min时TOC去除率为81.7%,明显优于市售P25纳米TiO_2。这主要归功于所制备纳米TiO_2表面残留的有机物提高了光生电子-空穴对的分离能力,以及纳米粒子的小尺寸效应和较大的比表面积。溶液p H为9时TC的降解率更高。该催化剂具有较好的光催化稳定性。活性基团捕获实验表明,纳米TiO_2光催化降解TC过程中空穴起主要作用。

Preparation of nano TiO2 by microwave-induced hydrolysis and photocatalytic degradation of tetracycline hydrochloride

The nano TiO₂ photocatalyst was rapidly prepared by microwave-induced hydrolysis,and characterized by XRD,TEM,SEM,BET and EDS. The anatase phase TiO₂ with an average grain size of about 7.5 nm was prepared by the method in 10 min. The tetracycline hydrochloride（TC）was degraded by the photocatalyst under UV light. Under the conditions of TC mass concentration 100 mg/L,and catalyst amount 0.5 g/L,the degradation rate of TC reached 92.9% after 40 min irradiation and the removal rate of TOC reached 81.7% after 60 min irradiation,which was much better than those by commercial P25 nano TiO₂. It was due to the increased separation ability of photogenerated electron-hole pairs because of organic residue on the surface of as-prepared nano TiO₂,and the small-size effect and large specific surface area of the nano particles. The degradation rate of TC was higher at the initial solution pH of 9. The catalyst had good photocatalytic stability. The results of active-group-capture experiments showed that the holes in nano TiO₂ played a leading role in the process of photocatalytic degradation of TC.