Monteagudo J M, Durán A, Guerra J, García-Peña F, Coca P
Department of Chemical Engineering, Escuela Técnica Superior de Ingenieros Industriales, University of Castilla-La Mancha, Avda. Camilo José Cela 3, 13071 Ciudad Real, Spain.
Chemosphere. 2008 Mar;71(1):161-7. doi: 10.1016/j.chemosphere.2007.10.067. Epub 2007 Dec 19.
The heterogeneous TiO2 assisted photocatalytic degradation of wastewater from a thermoelectric power station under concentrated solar light irradiation using a Fresnel lens has been studied. The efficiency of photocatalytic degradation was determined from the analysis of cyanide and formate removal. Firstly, the influence of the initial concentration of H2O2 and TiO2 on the degradation kinetics of cyanides and formates was studied based on a factorial experimental design. Experimental kinetic constants were fitted using neural networks. Results showed that the photocatalytic process was effective for cyanides destruction (mainly following a molecular mechanism), whereas most of formates (degraded mainly via a radical path) remained unaffected. Finally, to improve formates degradation, the effect of lowering pH on their degradation rate was evaluated after complete cyanide destruction. The photooxidation efficiency of formates reaches a maximum at pH around 5-6. Above pH 6, formate anion is subjected to electrostatic repulsion with the negative surface of TiO2. At pH<4.5, formate adsorption and photon absorption are reduced due to some catalyst agglomeration.
研究了在聚光太阳光照射下，使用菲涅耳透镜，非均相二氧化钛辅助光催化降解热电厂废水的情况。通过分析氰化物和甲酸盐的去除情况来确定光催化降解效率。首先，基于析因实验设计，研究了过氧化氢和二氧化钛初始浓度对氰化物和甲酸盐降解动力学的影响。使用神经网络拟合实验动力学常数。结果表明，光催化过程对氰化物的破坏有效（主要遵循分子机制），而大部分甲酸盐（主要通过自由基途径降解）未受影响。最后，为提高甲酸盐的降解率，在氰化物完全破坏后评估了降低pH值对其降解速率的影响。甲酸盐的光氧化效率在pH约为5 - 6时达到最大值。pH高于6时，甲酸根阴离子与二氧化钛的负表面发生静电排斥。在pH < 4.5时，由于一些催化剂团聚，甲酸盐的吸附和光子吸收减少。
