稀土Ce^(3+)掺杂Bi_2WO_6光催化降解罗丹明B的研究

Investigation of rhodamine B photocatalytic degradation by Ce^(3+) doped Bi_2WO_6

采用水热合成法制备稀土元素Ce3+掺杂Bi2WO6光催剂,通过X射线衍射、场发射电镜扫描、紫外-可见漫反射光谱、N2物理吸附-脱附等手段对合成材料的结构、形貌、光吸收等物理化学性能进行表征,并以染料废水中罗丹明B的降解考察其光催化活性.结果表明,Ce3+掺杂量为0.05%时,其结晶度好、颗粒较均匀、具有较强的可见光吸收性能,且比表面积比纯Bi2WO6提高近10%以上,对罗丹明B的去除效果最好;催化剂用量越高、罗丹明B的初始浓度越低、反应溶液p H值越低、H2O2的浓度越高越有利于Ce/Bi2WO6对罗丹明B的吸附和降解;而阴阳离子的影响各不相同:NO3-、SO42-没有太大的影响;Na+、K+、Ca2+、Mg2+、Cl-的加入均促使的染料的去除;HCO3-抑制了罗丹明B的吸附,但是却促进了光降解.另外,经重复使用3次,光催化降解速率常数并没有降低,表明稀土Ce3+改性Bi2WO6是一种有效稳定的光催化剂.

Rare earth element Ce^3＋ doped Bi2WO6 was synthesized by hydrothermal method. The physicochemical properties of prepared materials were characterized by XRD, SEM, UV-vis DRS and N2adsorption-desorption. Rhodamine B was used to as the objective pollutant to investigate the photocatalytic activity of Ce/Bi2WO6. As a result, Ce/Bi2WO6（0.05%） has the optimum phtocatalytic activity to removal rhodamine B, which has good crystalinity, uniform shape and size, strong visible light-responsible property and the higher SBET value（ca. 10%） than pure Bi2WO6. Much more amount of catalyst, less concentration of Rhodamine B, lower p H value of the reaction solution and higher concentration of H2O2 all benefit the adsorption and photodegradation of Rhodamine B by Ce/Bi2WO6. The common inorganic ions showed different effects on Rhodamine B degradation. There was no significantly effect of NO3^- and SO4^2-; but the addition of Na^＋, K^＋, Ca^2＋, Mg^2＋, Cl^- inhibited the removal of the dye. HCO3- reduced the adsorption of Rhodamine B but accelerated its photodegradation. In addition, after three recycling runs, Ce/Bi2WO6（0.05%） still kept high photocatalytic activities on the degradation of rhodamine B.