构树叶制备介孔TiO_(2)/SiO_(2)复合材料的光催化性能及其动力学研究

On photocatalytic properties and kinetics of mesoporous TiO_(2)/SiO_(2) composites prepared from Broussonetia papyrifear leaves

以构树叶为生物模板和硅源,以钛酸四丁酯(TBOT)为前驱体,采用浸渍法制备了不同质量分数(w(TiO_(2))=0、2.6%、4.0%、5.5%、7.0%和8.6%)的TiO_(2)/SiO_(2)复合材料.采用XRD、FTIR、SEM、XPS、TEM、BET、XRF、UV-Vis DRS等对复合材料进行了表征.结果表明,TiO_(2)/SiO_(2)复合材料主要由锐钛矿相TiO_(2)组成,形成了平均粒径为500 nm的纳米球.该材料具有典型的介孔结构,平均孔径为7.2 nm,比表面积为50.42 m^(2)/g.以罗丹明B作为模型,在紫外光照射下进行光催化降解实验来评价不同材料的光催化活性及进行动力学研究.实验结果表明,与w(TiO_(2))=0催化剂相比,改变TiO_(2)质量分数所制备的TiO_(2)/SiO_(2)材料均表现出较强的光催化活性,其中掺杂w(TiO_(2))=5.5%的催化剂具有最优的催化性能;动力学研究表明,在不同催化材料存在下,紫外光催化降解罗丹明B均符合拟一级反应特征.在室温下紫外光照90 min,w(TiO_(2))=5.5%的催化材料对罗丹明B溶液几乎完全降解,表观速率常量k达到最大值0.0911 min^(-1),是w(TiO_(2))=0的21.69倍.

The TiO_(2)/SiO_(2) composites were prepared with different mass fractions of precursor(w(TiO_(2))=0,2.6%,4.0%,5.5%,7.0%and 8.6%)by impregnation method,and using Broussonetia papyrifear leaves as biological template and silicon source and tetrabutyltitanate(TBOT)as precursor.The composite materials were characterized by XRD,FTIR,SEM,XPS,TEM,BET,XRF,UV-Vis DRS,etc.The results showed that the TiO_(2)/SiO_(2) composites mainly consisted of anatase phase TiO_(2),and forming nanospheres with an average particle size of 500 nm.The composite posseses typical mesopore structure with an average pore size of 7.2 nm and a specific surface area of 50.42 m^(2)/g.The photocatalytic degradation experiments were carried out to evaluate the photocatalytic activity and kinetics of the materials under UV light irradiation using rhodamine B as the research object.The results show that compared with w(TiO_(2))=0 catalyst,the TiO_(2)/SiO_(2) materials prepared by changing the mass fraction of TiO_(2) show strong photocatalytic activity,and the catalyst doped w(TiO_(2))=5.5%shows the best catalytic effect.The kinetic study shows that the UV photocatalytic degradation of rhodamine B conforms to the characteristics of quasi first order reaction in the presence of different catalytic materials.Under ultraviolet light for 90 min at room temperature,the rhodamine B solution was almost completely degraded by the w(TiO_(2))=5.5%catalyst,and the apparent rate constant k reached the maximum value of 0.0911 min^(-1),21.69 times that of w(TiO_(2))=0 catalyst.