Monteagudo J M, Durán A
Universidad de Castilla-La Mancha, Departamento de Ingeniería Química, Escuela Técnica Superior de Ingenieros Industriales, Avda. Camilo José Cela, 1, 13071 Ciudad Real, Spain.
Chemosphere. 2006 Nov;65(7):1242-8. doi: 10.1016/j.chemosphere.2006.04.057. Epub 2006 Jun 9.
The decoloration and mineralization of the azo dye orange II under conditions of artificial ultraviolet light and solar energy concentrated by a Fresnel lens in the presence of hydrogen peroxide and TiO(2)-P25 was studied. A comparative study to demonstrate the viability of this solar installation was done to establish if the concentration reached in the focus of the Fresnel lens was enough to improve the photocatalytic degradation reaction. The degradation efficiency was higher when the photolysis was carried out under concentrated solar energy irradiation as compared to UV light source in the presence of an electron acceptor such us H(2)O(2) and the catalyst TiO(2). The effect of hydrogen peroxide, pH and catalyst concentration was also determined. The increase of H(2)O(2) concentration until a critical value (14.7 mM) increased both the solar and artificial UV oxidation reaction rate by generating hydroxyl radicals and inhibiting the (e(-)/h(+)) pair recombination, but the excess of hydrogen peroxide decreases the oxidation rate acting as a radical or hole scavenger and reacting with TiO(2) to form peroxo-compounds, contributing to the inhibition of the reaction. The use of the response surface methodology allowed to fit the optimal values of the parameters pH and catalyst concentration leading to the total solar degradation of orange II. The optimal pH range was 4.5-5.5 close to the zero point charge of TiO(2) depending on surface charge of catalyst and dye ionization state. Dosage of catalyst higher than 1.1 gl(-1) decreases the degradation efficiency due to a decrease of light penetration.
研究了在人工紫外光以及由菲涅耳透镜聚集的太阳能条件下，偶氮染料橙II在过氧化氢和TiO(2)-P25存在时的脱色和矿化情况。进行了一项对比研究以证明该太阳能装置的可行性，从而确定在菲涅耳透镜焦点处达到的浓度是否足以提高光催化降解反应。与在电子受体如H(2)O(2)和催化剂TiO(2)存在下的紫外光源相比，在聚光太阳能辐射下进行光解时降解效率更高。还测定了过氧化氢、pH值和催化剂浓度的影响。过氧化氢浓度增加至临界值（14.7 mM）时，通过产生羟基自由基和抑制（e(-)/h(+)）对的复合，提高了太阳能和人工紫外氧化反应速率，但过量的过氧化氢作为自由基或空穴清除剂与TiO(2)反应形成过氧化合物，降低了氧化速率，导致反应受到抑制。使用响应面方法能够拟合pH值和催化剂浓度的最佳值，从而实现橙II的完全太阳能降解。最佳pH范围为4.5 - 5.5，接近TiO(2)的零电荷点，这取决于催化剂的表面电荷和染料的电离状态。催化剂用量高于1.1 gl(-1)时，由于光穿透率降低，降解效率下降。
