Laboratório de Catálise e Materiais, Laboratório Associado LSRE/LCM, Departamento de Engenharia Química-Faculdade de Engenharia, Universidade do Porto, Portugal.
ChemSusChem. 2010 May 25;3(5):609-18. doi: 10.1002/cssc.200900262.
A nanostructured multiwalled carbon nanotube (CNT) and titanium dioxide composite catalyst is prepared by a modified acid-catalyzed sol-gel method. Pure anatase TiO(2) and the CNT-TiO(2) composite are tested in the photocatalytic degradation of four para-substituted phenols: 4-chlorophenol, 4-aminophenol, 4-hydroxybenzoic acid and 4-nitrophenol. The effect of several operational parameters on the photoefficiency of the composite catalyst is studied by using 4-chlorophenol as model compound, namely catalyst loading, pH of the medium, hydrogen peroxide concentration, substrate concentration. A relationship between the Hammett constant of each para-substituted phenolic compound and its degradability by the photocatalysts is found. The effect of the carbon phase in the catalyst is ascribed to its photosensitizer action. A clear beneficial effect is observed for the degradation of 4-aminophenol and 4-chlorophenol. For the molecules with stronger electron-withdrawing (deactivating) groups, such as 4-hydroxybenzoic acid and 4-nitrophenol, no synergy effect is observed.
采用改进的酸催化溶胶-凝胶法制备了一种纳米结构的多壁碳纳米管（CNT）和二氧化钛复合催化剂。在光催化降解四种对位取代酚：4-氯苯酚、4-氨基酚、4-羟基苯甲酸和 4-硝基苯酚中，对纯锐钛矿 TiO(2)和 CNT-TiO(2)复合材料进行了测试。以 4-氯苯酚为模型化合物，研究了几种操作参数对复合催化剂光效率的影响，即催化剂负载量、介质 pH 值、过氧化氢浓度、底物浓度。发现每个对位取代酚化合物的哈米特常数与其被光催化剂降解的关系。催化剂中碳相的作用归因于其光敏作用。对于 4-氨基酚和 4-氯苯酚的降解，观察到明显的有益效果。对于具有更强吸电子（失活）基团的分子，如 4-羟基苯甲酸和 4-硝基苯酚，没有观察到协同效应。
