Department of Environmental Health Engineering, School of Health, Guilan University of Medical Sciences, Rasht, Iran.
J Environ Health Sci Eng. 2013 Aug 2;11(1):23. doi: 10.1186/2052-336X-11-23.
Effect of different type of organic compounds (humic acid, oxalate, ethylenediaminetetraacetic acid, nitrilotriacetic acid, phenol) on the photocatalytic removal of cyanide with TiO2 or ZnO was studied in this work with variation of the solution pH, contact time, initial cyanide concentration and type of organic compounds. Photocatalytic oxidation efficiency of cyanide with TiO2 was greatly affected by the solution pH. It increased as the solution pH decreased. Also maximum removal of cyanide by ZnO was observed near at neutral pH because of the reduced photocatalytic activity of ZnO at exceedingly low and high pH values originated from either acidic/photochemical corrosion of the catalyst and/or surface passivation with Zn(OH)2. Removal efficiency of cyanide greatly decreased in the presence of humic acid, ethylenediaminetetraacetic acid, nitrilotriacetic acid compared to that without presence of organic compound because of the competitive oxidation as well as surface blocking by relatively large organic compounds. The oxidation pattern of cyanide was better described by first-order kinetic model. Finally photocatalytic reaction with TiO2 or ZnO can be effectively applied to treat synthetic wastewater contaminated with cyanide.
本工作研究了不同类型的有机化合物（腐殖酸、草酸盐、乙二胺四乙酸、氮三乙酸、苯酚）对 TiO2 或 ZnO 光催化去除氰化物的影响，考察了溶液 pH 值、接触时间、初始氰化物浓度和有机化合物类型的变化。TiO2 光催化氧化氰化物的效率受溶液 pH 值的影响很大。随着溶液 pH 值的降低而增加。由于 ZnO 在极低和极高 pH 值下的光催化活性降低，源于催化剂的酸性/光化学腐蚀和/或 Zn(OH)2 的表面钝化，ZnO 对氰化物的最大去除率在接近中性 pH 值时观察到。与不存在有机化合物相比，由于相对较大的有机化合物的竞争氧化和表面阻塞，氰化物的去除效率在腐殖酸、乙二胺四乙酸、氮三乙酸存在的情况下大大降低。氰化物的氧化模式较好地用一级动力学模型描述。最后，TiO2 或 ZnO 的光催化反应可以有效地应用于处理含有氰化物的合成废水。
