Photocatalytic degradation of Rhodamine B using nanocrystalline TiO2-zeolite surface composite catalysts: effects of photocatalytic condition on degradation efficiency
Photocatalytic degradation of Rhodamine B using nanocrystalline TiO2-zeolite surface composite catalysts: effects of photocatalytic condition on degradation efficiency
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DOI：
10.1039/c1cy00012h
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发表时间：
2011-01-01
影响因子：
5
通讯作者：
Chen Wei
中科院分区：
文献类型：
--
作者：
Li You-ji;Chen Wei
采用一种新的方法制备了纳米TiO 2-沸石表面复合材料，超临界预处理辅助下的溶胶-凝胶法。采用X射线衍射（XRD）、热重-差热分析（TG-DTA）、扫描电镜（SEM）和比表面积分析等手段对样品进行了表征。研究了TZS在紫外光下催化降解罗丹明B（RhB）染料的行为，考察了溶液pH值、光照强度、光照时间、TZS的TiO 2包覆率、TZS在溶液中的浓度以及RhB的初始浓度等因素对降解效果的影响。光催化降解RhB的动力学符合准一级动力学规律。据观察，沸石的存在下，提高了二氧化钛的光效率，由于协同效应的改善吸附的RhB与有效的离域的光生电子和TiO 2的电子。此外，在超临界CO2中预处理的沸石载体进一步提高了TiO 2的光催化活性。这主要归因于TZS比溶胶-凝胶法制备的TiO 2-沸石复合材料具有更高的比表面积。当RhB浓度为2 mg L-1，光照强度为32 mW cm-2，pH为10，催化剂用量为6 g L-1时，RhB光催化降解速率最快。
Nanocrystalline TiO2-zeolite surface (TZS) composites were prepared by a novel technique, i.e., sol-gel method with the assistance of supercritical pretreatment. The samples were characterized by X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM) and BET surface area analysis. The behavior of TZS in the catalytic degradation of Rhodamine B (RhB) dye under UV-light was examined as a function of the pH values in solution, light intensity, irradiation time, TiO2 coating ratio of TZS and its concentration in solution, and initial RhB concentration. The kinetics of photocatalytic RhB degradation was found to follow a pseudo-first-order rate law. It was observed that the presence of the zeolites enhanced the photoefficiency of the titanium dioxide due to synergistic effects of the improved adsorption of RhB with efficient delocalisation of photogenerated electrons and TiO2 photocatalysis. Furthermore, the photocatalytic activity of TiO2 was further enhanced by a zeolite support pretreated in supercritical CO2. It is mainly attributed to the fact that TZS has high surface area in comparison with TiO2-zeolite (TZ) composites prepared by the sol-gel method only. The optimal conditions were a concentration of 2 mg L-1 at pH 10 with 32 mW cm(-2) of illumination and a catalyst content of 6 g L-1 for the fastest rate of RhB photocatalytic degradation.