摘要
In order to develop efficient photocatalysts,great efforts have been made to reduce hexavalent chromium to trivalent chromium.The photocatalytic efficiency of this reduction depends largely on the adsorption and diffusion of hexavalent chromium ions on the surface of the photocatalyst.In this paper,polyanilineTiO2 composite can effectively improve the photocatalytic reduction performance and stability of hexavalent chromium ion.The effect of polyaniline(PANI) thickness on Cr(VI) activity and stability of photocatalytic reduction was studied by adjusting the content of PANI on Mesoporous TiO2(MT) surface.Under the irradiation conditions,the reaction results showed that the reduction rate was 100%,and the maximum reaction rate reached 0.62 min-1 when the PANI modification was 3.0%.Moreover,the results showed that the reduction performance remained 100% after ten cycles.The main reason is that the PANI modified on the surface of TiO2 is rich in positively charged amino group,which can efficiently adsorb the reactant Cr(VI),and make the product Cr(III) leave the reaction interface quickly,thus ensuring the performance of photocatalyst.
通过设计高效的光催化剂,将六价铬还原为三价铬已成为近年来研究的热点.光催化还原六价铬的效率在很大程度上取决于六价铬离子在光催化剂表面的吸附和反应后三价铬离子在催化剂表面的脱附能力.聚苯胺-二氧化钛复合材料可以有效提高六价铬离子的光催化还原性能和稳定性.通过调节聚苯胺(PANI)在二氧化钛(MT)表面修饰的含量,本文研究了聚苯胺的厚度对光催化还原六价铬的活性和光催化剂稳定性的影响.反应结果表明,在紫外光照射下,当聚苯胺的修饰量为3.0 wt%时,六价铬的还原率为100%,最大反应速率为0.62 min–1.结果表明,经过10次循环后,还原性能依旧保持在100%.主要原因是二氧化钛表面修饰的聚苯胺富含氨基基团,在酸性反应体系中,表面带正电,可以有效吸附六价铬阴离子,使产物三价铬阳离子迅速离开反应界面,从而促进了光催化剂的性能.同时,二氧化钛与聚苯胺的界面形成相互作用,促进了光生电荷的分离,提高了光催化还原活性.本研究为设计高效光催化剂用于净化处理六价铬离子开辟了新的途径.
基金
supported by the National Natural Science Foundation of China(21876114,21761142011,and 51572174)
Shanghai Government(19160712900)
International Joint Laboratory on Resource Chemistry(IJLRC),and Ministry of Education of China(PCSIRT_IRT_16R49)
supported by The Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning
Shuguang Research Program of Shanghai Education Committee.
