La^(3+)掺杂TiO_(2)粉体的高分子网络凝胶法制备工艺优化及其光催化降解甲基橙性能(英文)

Optimization of Processes Conditions of La^(3+)-doped TiO_(2)Powder by Polymer Network Gel Method and its Photocatalytic Degradation of Methyl Orange Performance

采用高分子网络凝胶法制备La^(3+)掺杂TiO_(2)粉体,通过正交实验优化制备工艺,采用比表面积测试(BET)、X射线衍射仪(XRD)、紫外-可见光谱仪(UV-Vis)和扫描透射电子显微镜(STEM)对TiO_(2)粉体的晶体结构和光吸收性能进行了表征,并以甲基橙为目标进行了光催化降解实验。结果表明:高分子网络凝胶法制备La^(3+)掺杂TiO_(2)粉体时对TiO_(2)光吸收波长影响最大的是煅烧温度,其次是掺杂量,最后是保温时间;正交实验得到的最优制备条件为:La^(3+)掺杂量为0.5%mol、煅烧温度为800℃,保温时间为30 min;煅烧温度过高与过低都不利于提高La^(3+)掺杂TiO_(2)的光催化活性,其存在一个最佳的温度范围:650~700℃;La^(3+)掺杂抑制了锐钛矿相向金红石相的转变,也抑制了晶粒的长大,但当La^(3+)掺杂量为1.0%mol时,其光催化效果最好;二氧化钛光催化降解甲基橙是零级反应,掺杂并没有改变光催化反应类型。

La^(3+)-doped TiO_(2)powder was prepared by using a polymer network gel method,and the preparation process was optimized through orthogonal experiments.The crystalline structure and light absorption properties of TiO_(2)powder were characterized by BET,XRD,UV-Vis and STEM,while photocatalytic degradation experiments were carried out with methyl orange as a target.The results show that when La^(3+)doped TiO_(2)powder was prepared by using the polymer network gel method,the calcination temperature had the most significant impact on the optical absorption wavelength of TiO_(2),followed by the doping amount and the holding time in order.The optimal preparation conditions determined by orthogonal experiments are as follows.La^(3+)doping amount is 0.5%mol,the calcination temperature is 800℃,and the holding time is 30 min.When the calcination temperature was too high or too low,the improvement of photocatalytic activity of La^(3+)doped TiO_(2)was hindered,and the optimal temperature range was between 650℃and 700℃.La^(3+)doping not only inhibited the transition from anatase to rutile phase,but also inhibited grain growth.When the doping amount of La^(3+)was 1.0%mol,however,the photocatalytic effect was the best.The photocatalytic degradation of methyl orange by titanium dioxide was a zero-level reaction,and doping did not change the type of photocatalytic reaction.