Solar photocatalytic degradation of reactive blue 4 using a Fresnel lens

Solar Concentration for Wastewaters Remediation: A Review of Materials and Technologies

As the effectiveness of conventional wastewater treatment processes is increasingly challenged by the growth of industrial activities, a demand for low-cost and low-impact treatments is emerging. A possible solution is represented by systems coupling solar concentration technology with advanced oxidation processes (AOP). In this paper, a review of solar concentration technologies for wastewater remediation is presented, with a focus on photocatalyst materials used in this specific research context. Recent results, though mostly on model systems, open promising perspectives for the use of concentrated sunlight as the energy source powering AOPs. We identify (i) the development of photocatalyst materials capable of efficiently working with sunlight, and (ii) the transition to real wastewater investigation as the most critical issues to be addressed by research in the field.

Comparative Study of Advanced Oxidation Processes to Treat Petroleum Wastewater

This study was carried out to compare the performance of different oxidation processes, such as solar photo-Fenton reaction, solar photocatalysis by TiO2, and the combination of the two for the treatment of petroleum wastewater from Sohar Oil Refinery by a central composite design with response surface methodology. The degradation efficiency was evaluated in terms of chemical oxygen demand (COD) and total organic carbon (TOC) reductions. Solar photocatalysis by the TiO2/Fenton method improved the performance of the photocatalyst at neutral pH for petroleum wastewater without the need to adjust the pH during this treatment. Under acidic conditions, the solar photo-Fenton process is more efficient than solar TiO2photocatalysis while it is less efficient under alkaline conditions. The TiO2dosage and pH are the two main factors that improved the TOC and COD reductions in the solar photocatalysis using combined TiO2/Fenton and the solar TiO2photocatalysis processes while the pH and H2O2concentration are the two key factors that affect the solar photo-Fenton process.

Photocatalytic degradation using design of experiments: a review and example of the Congo red degradation

The use of chemometric methods such as response surface methodology (RSM) based on statistical design of experiments (DOEs) is becoming increasingly widespread in several sciences such as analytical chemistry, engineering and environmental chemistry. Applied catalysis, is certainly not the exception. It is clear that photocatalytic processes mated with chemometric experimental design play a crucial role in the ability of reaching the optimum of the catalytic reactions. The present article reviews the major applications of RSM in modern experimental design combined with photocatalytic degradation processes. Moreover, the theoretical principles and designs that enable to obtain a polynomial regression equation, which expresses the influence of process parameters on the response are thoroughly discussed. An original experimental work, the photocatalytic degradation of the dye Congo red (CR) using TiO(2) suspensions and H(2)O(2), in natural surface water (river water) is comprehensively described as a case study, in order to provide sufficient guidelines to deal with this subject, in a rational and integrated way.

Evaluating the photo-catalytic application of Fenton's reagent augmented with TiO(2) and ZnO for the mineralization of an oil-water emulsion

In the present study, homogenous (photo-Fenton) and heterogeneous photo-assisted systems (Fenton/TiO(2)/UV, Fenton/ZnO/UV and Fenton/TiO(2)/UV/Air) were investigated for the treatment of a diesel-oil wastewater emulsion. The augmentation of the photo-Fenton process by heterogeneous TiO(2) increased the reaction rate, in terms of COD reduction efficiency from 61% to 71%. Furthermore, the COD removal efficiency was increased to 84% when air was bubbled through the reactants. However, if the Fenton/TiO(2) /UV/Air process is to be utilized as a treatment for this wastewater, the separation of the TiO(2) from the treated effluent would need further consideration.

Solar TiO2-assisted photocatalytic degradation of IGCC power station effluents using a Fresnel lens

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.