活性炭孔结构对TiO2/AC复合光催化剂光催化活性的影响

以4种表面化学性质相近, 而孔结构差异较大的活性炭(AC)为原料, 采用酸催化水解法合成了系列TiO2/AC复合催化剂, 考查活性炭孔结构对复合光催化剂活性的影响. 以苯酚为模型物, 考察了催化剂的活性；以低温(77 K)液氮吸附测定活性炭的比表面积、孔容和孔径分布；以Boehm滴定及元素分析定量表征活性炭表面化学性质. 以SEM观测复合催化剂表面TiO2的分散性能；以X射线衍射(XRD)、漫反射光谱(DRS)测试光催化剂晶相结构参数及光吸收阈值. 结果表明, 活性炭孔结构性质对TiO2/AC活性影响显著. AC1、AC2、AC3、AC4对TiO2活性提高的协同系数分别为1.55、2.03、1.28、1.43. 协同系数大小与接触界面面积变化值(⊿S)趋势相似. 具有发达的微孔及适量中孔结构的TiO2/AC复合光催化剂的催化活性最高.

Effect of Pore Structure of Activated Carbon on the Photocatalytic Activity of TiO2/AC Composite Photocatalyst

With the aim of investigating the effect of pore structure of activated carbon (AC) on the photocatalytic activity of TiO2/AC composite photocatalyst, 4 kinds of AC with similar surface chemical characteristics and different pore structures were used and compared. Phenol degradation was used for photocatalytic activity test. N2 adsorption isotherm (77 K) was used for BET surface area (SBET), pore volume, and pore size distribution measurement. Boehm titration and elemental analysis were used for surface chemical characteristics determination. XRD, DRS, and SEM were used to characterize the crystal structure, spectra characteristics, and surface properties. The results showed that the pore structure of AC had significant effect on the photocatalytic activity of TiO2/AC. The synergistic coefficients for the activity enhancement of AC1, AC2, AC3, and AC4 were 1.55, 2.03, 1.28, and 1.43, respectively, which exhibited the similar tendency with the contact interface (⊿S). AC with both developed micropore and mesopore structures exhibited the highest activity when composited with TiO2. The developed micropore structure can provide more adsorption sites for pollutant molecules. More mesopore can be beneficial to the transfer of adsorbed phenol from adsorption sites to active TiO2. Also, the mesopore can inhibit the aggregation of nano-size TiO2, improve its dispersion and increase the contact interface between AC and TiO2.