Degradation Of Organic Pollutants From Aqueous Solution By Advanced Oxidation Processes

Advanced Oxidation Processes (AOPs) are emerging as powerful and efficient techniques for the treatment of organic wastewaters. In the present study, ultrasonic technology and photocatalytic oxidation, as the important components of AOPs, were utilized in the degradation of organic pollutants from aqueous solutions.Ultrasonic degradation is proven to be effective for removing organic pollutants from aqueous solutions. In this study, removal of fuchsin basic from aqueous solutions by ultrasound was investigated. The effects of operating parameters such as ultrasound power, initial pH and temperature on the ultrasonic degradation were studied. Addition of catalyst Fe2+had a markedly positive effect on degradation. But addition of heterogeneous catalyst TiO2affected degradation slightly. Addition of radical scavenger suppressed fuchsin basic degradation significantly.Response surface methodology (RSM) is a collection of mathematical and statistical techniques for empirical model building. By design of experiments, the objective is to optimize a response which is influenced by several independent variables. Degradation of naproxen by combination of Fenton reagent and ultrasound irradiation was investigated and experiment conditions were optimized by using response surface methodology. Some preliminary runs were performed with the purpose of establish the variable ranges. After that, a central composite design was applied to evaluate the effect of H2O2, Fe2+and NPX concentration after10min, at pH=3and ultrasonic power amplitude at90%. Optimization by the response surface methodology was utilized to obtain the optimum of concentration of H2O2, Fe2+and NPX that resulted in the highest response.Industrial carbon nanotubes have been successfully applied in adsorption of environmental pollutants. The adsorption behaviour of Acid orange74(AO74) from aqueous solution by the combination of ultrasound and multi-walled carbon nanotubes (MWCNTs) was investigated. The combination method of ultrasound and MWCNTs achieved better results than either MWCNTs or ultrasound alone. The effects of dosage of MWCNTs, ultrasound time, temperature, initial concentration and pH of AO74solution were studied. Experimental isotherm data was represented with Langmuir and Frendlich adsorption isotherms models. The adsorption data were found to follow the Langmuir model better than the Frendlich model. Thermodynamics analysis suggested that adsorption of AO74onto MWCNTs was driven by a physisorption process. The adsorption of AO74follows pseudo second-order kinetics.Researches of sunlight degradation of different types of dyes (anionic and cationic), catalyzed by nanometer TiO2catalyst were did. The adsorptive and catalytic characteristics of different TiO2catalysts were investigated. Acid orange74was chosen as the object substrate to investigate the effects of dosage of the catalyst, dye concentration and initial pH value of the solution. The degradation products were analyzed by anion chromatography and it was found thatacid orange74has not been completely mineralized by photocatalytic oxidation.TiO2/graphene composites were synthesized by hydrothermol method. Influence of dosage of grapheme oxide on the photocatalytic activity of TiO2/graphene was studied. The results showed that the TiO2/Graphene composite exhibited a higher (nearly2.5times) degradation activity than pure TiO2. The enhancement of the photocatalytic activity could be attributed to the excellent electronic conductivity of graphene, which results in that the photogenerated electrons can transport to the surface of the composites more easily, thus inhibiting the recombination between photo-induced electrons and holes.