N、Zn共掺杂纳米TiO₂光催化剂的制备及其应用研究

【作者】 黄兰粉；

【导师】 宋宁；

【作者基本信息】 昆明理工大学 ， 有色金属冶金， 2010， 硕士

【摘要】 纳米TiO2光催化剂能将一些毒性大、生物难降解的有机污染物彻底催化氧化为H2O和CO2等小分子,且因其光催化活性高、化学性质稳定、无毒无害等特性被广泛研究和应用。但纳米TiO2的禁带宽度大,在实际应用中还存在光响应波长短等问题。开展纳米TiO2掺杂改性研究,拓展TiO2的光谱响应范围,使其光响应波长由紫外区(波长300-400nm)红移至可见光区(波长400-800nm),将有利于光催化氧化技术在废水处理中的推广应用。本论文研究N、Zn共掺杂纳米TiO2(简称NZTO)光催化剂的制备及其应用,以TiOSO4和ZnSO4·7H2O为原料,NH3-H2O为沉淀剂,采用化学共沉淀法制备具有可见光催化活性的NZTO纳米粉体,讨论了pH、反应温度、反应时间、超声陈化时间、氨水浓度等对NZTO纳米粉体前躯体性能的影响。通过TG-DTA、XRD、UV-VIS等手段对NZTO纳米粉体进行表征。在本实验条件下,制备NZTO纳米粉体的最佳工艺条件为：pH为8、反应温度为室温、反应时间为30min、超声20min、陈化时间为60min、氨水浓度为7mol/L,剧烈搅拌,缓慢滴定,制得24.5nm的NZTO纳米粉体,其光吸收区域由原来的紫外光区拓展至可见光区,光催化效率比未掺杂的纳米Ti02高,极大程度上提高了对太阳光的利用。将制备的NZTO纳米粉体应用于偶氮染料甲基橙为模拟污染物的有机废水,进行了光催化反应研究,并考察了不同条件下的NZTO纳米粉体对甲基橙水溶液的催化降解性能。通过正交设计实验得出降解甲基橙的最佳工艺条件为：光照时间6h,初始浓度5mg/L,pH为1、催化剂投加量1g/L,氧化剂(H2O2)加入量0.8mL/500mL。另外,还采用正交设计实验的方法考察了pH值、Zn掺杂量、煅烧温度等不同条件下所制得的NZTO纳米粉体,在太阳光下的光催化性能研究。实验结果表明：pH值为9,Zn掺杂量为2%,煅烧温度为500℃下制备的纳米粉体的光催化降解率最高。并在最佳条件下做验证实验,得出在太阳光下照射6h,有超声分散、搅拌的条件下降解甲基橙,其降解率高达98.2%,光催化剂重复使用4次后降解率仍可到达74.2%。更多还原

【Abstract】 Nanometer titanium dioxide (TiO2) can degradated completely toxic organic pollutants into harmless carbon dioxide and water. Due to its high photo-catalytic acitivity, high chemical stability and harmless, the photocatalyst TiO2 has been widely investigated and used. However, the use of this photocatalyst is currently limited for that light irradiation with rather short light wavelength is needed for the occurrence of the photo-catalytic rea-ction. Research on the doping and modification of TiO2, which aims at extending its optical response scope from the ultraviolet light (wavelength-range 300-400nm) to the visible sp-ectral range (wavelegth-range 400-800nm), will promote the photocatalysis technology in practical wastewater treatment.In this paper, N, Zn co-doped TiO2 (Abbreviation NZTO) nanometer photocatalysts, which have photo-catalysis in invisible spectral rang, were prepared with TiOSO4 and ZnSO4·7H2O as raw materials, NH3·H2O as precipitant by co-precipitation method. The in-fluence factors on average diameter of NZTO powders were inspects, such as pH, reaction temperature, precipitant concentration, reaction time and so on. It was characterized by TG-DTA, XRD and UV-VIS so on. The results showed that under the optimal condition, pH value of 7, NH3·H2O concentration of 7mol/l,30min reaction time, common temperature, the NZTO powders had 24.5nm average diameter. Its absorption range was extended to the visible rang and photocatalysis ratio was higher than un-doped TiO2 nano-meter powders.Azo dyes, methyl orange was used as the pollution reactant to evaluate the photo-catalytic activity of the NZTO catalyst samples by orthogonal experiments. The results showed that the optical conditions on degradation of methyl orange is the initial concen-tration of 5mg/L, pH values of 1, NZTO photo-catalyst dosage 1g/L, oxidant dosage(H2O2) 0.8ml/500mL. In addition, influence factors, such as pH, Zn coped weight, calcine temp-erature, were inspected on degradation ratio of the NZTO powders by orthogonal experi-ments. The results showed that the optimum condition is Zn 2wt%, pH values of 7, calcine temperature of 500℃. Verification experiment in the optimum conditions showed that the degradation ratio of methyl orange reached 98.2%, under sunshine for 6h, with ultrasound dispersing and whipping, and it’s still 74.2% four times reused.更多还原