Investigation of the solution initial pH effects on the performance of UV/Fe-ZSM5/H2O2 process

Effect of the solution initial pH was investigated on the performance of photo-Fenton process using Fe-ZSM5 zeolite as a heterogeneous catalyst for degradation of azo dye Acid Red 14. All experiments were performed in a 1.0 L tubular closed circulation batch photo-reactor. The dye degradation quantum yield was maximal when the solution initial pH was about 5. An amount of about 0.3 mg L−1 of Fe ions leached out of the zeolite. However, monitoring Fe ion concentration during the experiments showed that the efficiency of the process is not due to the leached Fe ions. The effect of pH on decomposition rate of hydrogen peroxide in different systems such as H2O2 alone, UV/H2O2, UV/Zeolite and UV/Zeolite/H2O2 was explored in detail to explain the results obtained.</jats:p

Modeling and Optimization of Heterogeneous Photo-Fenton Process with Response Surface Methodology and Artificial Neural Networks

In this study, estimation capacities of response surface methodology (RSM) and artificial neural network (ANN) in a heterogeneous photo-Fenton process were investigated. The zeolite Fe-ZSM5 was used as heterogeneous catalyst of the process for degradation of C.I. Acid Red 14 azo dye. The efficiency of the process was studied as a function of four independent variables, concentration of the catalyst, molar ratio of initial concentration of H2O2 to that of the dye (H value), initial concentration of the dye and initial pH of the solution. First, a central composite design (CCD) and response surface methodology were used to evaluate simple and combined effects of these parameters and to optimize process efficiency. Satisfactory prediction second-order regression was derived by RSM. Then, the independent parameters were fed as inputs to an artificial neural network while the output of the network was the degradation efficiency of the process. The multilayer feed-forward networks were trained by the sets of input−output patterns using a backpropagation algorithm. Comparable results were achieved for data fitting by using ANN and RSM. In both methods, the dye mineralization process was mainly influenced by pH and the initial concentration of the dye, whereas the other factors showed lower effects

Photocatalytic degradation kinetics of Reactive Black 5 (RB5) dyestuff on TiO2 modified by pretreatment with ultrasound energy

In the photocatalytic degradation of Reactive Black 5 (RB5) dyestuff, the photocatalytic activity of Riedel-de Haen brand TiO2, whose photocatalytic activity is low, was increased by ultrasound energy applied as a photocatalyst in the experiments. The BET surface areas of TiO2 with and without ultrasound treatment were 38 and 4 m(2)/g. The initial dye concentration, temperature and the effects of light intensity on the photocatalytic degradation kinetics of RB5 were examined. It was determined that the photocatalytic degradation follows pseudo-first order kinetics, depending on the dye concentration. The activation energy of the reaction was determined to be 29.3 kJ/mol