Lei Jing, Liu Chengshuai, Li Fangbai, Li Xiaomin, Zhou Shungui, Liu Tongxu, Gu Minghua, Wu Qitang
The Faculty of Agriculture, Guangxi University, Nanning 630005, PR China.
J Hazard Mater. 2006 Sep 21;137(2):1016-24. doi: 10.1016/j.jhazmat.2006.03.028. Epub 2006 May 22.
To understand the photodegradation of azo dyes in natural aquatic environment, a novel photo-Fenton-like system, the heterogeneous iron oxide-oxalate complex system was set up with the existence of iron oxides and oxalate. Five iron oxides, including gamma-FeOOH, IO-250, IO-320, IO-420 and IO-520, were prepared and their adsorption capacity was investigated in the dark. The results showed that the saturated adsorption amount (gamma(max)) was ranked the order of IO-250 > IO-320 > gamma-FeOOH > IO-420 > IO-520 and the adsorption equilibrium constant (Ka) followed the order of IO-250 > IO-520 > gamma-FeOOH > IO-420 > IO-320. The effect of initial pH value, the initial concentrations of oxalate and orange I on the photodegradation of orange I were also investigated in different iron oxide-oxalate systems. The results showed that the photodegradation of orange I under UVA irradiation could be enhanced greatly in the presence of oxalate. And the optimal oxalate concentrations (C(ox)0) for gamma-FeOOH, IO-250, IO-320, IO-420 and IO-520 were 1.8, 1.6, 3.5, 3.0 and 0.8 mM, respectively. The photodegradation of orange I in the presence of optimal C(ox)0 was ranked as the order of gamma-FeOOH > IO-250 > IO-320 > IO-420 > IO-520. The optimal range of initial pH was at about 3-4. The first-order kinetic constant for the degradation of orange I decreased with the increase in the initial concentration of orange I. Furthermore, the variation of pH, the concentrations of Fe3+ and Fe2+ during the photoreaction were also strongly dependent on the C(ox)0 and iron oxides.
为了解偶氮染料在天然水环境中的光降解情况，在铁氧化物和草酸盐存在的条件下，建立了一种新型类光芬顿体系——非均相铁氧化物 - 草酸盐复合体系。制备了五种铁氧化物，包括γ - FeOOH、IO - 250、IO - 320、IO - 420和IO - 520，并在黑暗中研究了它们的吸附容量。结果表明，饱和吸附量（γ(max)）的顺序为IO - 250 > IO - 320 > γ - FeOOH > IO - 420 > IO - 520，吸附平衡常数（Ka）的顺序为IO - 250 > IO - 520 > γ - FeOOH > IO - 420 > IO - 320。还研究了初始pH值、草酸盐和橙黄I的初始浓度对不同铁氧化物 - 草酸盐体系中橙黄I光降解的影响。结果表明，在草酸盐存在下，UVA辐照下橙黄I的光降解可大大增强。γ - FeOOH、IO - 250、IO - 320、IO - 420和IO - 520的最佳草酸盐浓度（C(ox)0）分别为1.8、1.6、3.5、3.0和0.8 mM。在最佳C(ox)0存在下，橙黄I的光降解顺序为γ - FeOOH > IO - 250 > IO - 320 > IO - 420 > IO - 520。初始pH的最佳范围约为3 - 4。橙黄I降解的一级动力学常数随橙黄I初始浓度的增加而降低。此外，光反应过程中pH、Fe3 +和Fe2 +浓度的变化也强烈依赖于C(ox)0和铁氧化物。
