Catalyzed Oxidation Of PNP In Fenton-like Precess With Coal Fly Ash Activated By Acid

Coal fly ash is one of the solid wastes generated from coal-fired power station. Although the serious harm to mankind and environment. Fly ash has certain catalytic capacity because of the possessions of porous structure, large BET area and activated metallic oxide. P-Nitrophenol (PNP) is considered to be priority toxic pollutant by U.S. Environmental Protection Agency (EPA) because it is toxic, hardly biodegradable and highly persistent in the environment. Fenton-like oxidation processes are a kind of new type oxidation technique based on Fenton oxidation precesses. The processes can remove the refractory organic pollutions more effectively in wastewater. PNP was selected as model organic compound and fly ash as raw material in this report to study the acid activiation of fly ash and the performance of oxidizing PNP in Fenton-like process which consists of activated fly ash and H2O2.Firstly an inorganic acid which has the best activation property for fly ash was selected, and then raw fly ash (RFA) and activated fly ash (AFA) were investigated in terms of surface and physico chemical properties. Secondly the influence parameters about catalytic capacity of AFA were studied. At last, under the kinetic precess of generating-OH and oxidizing PNP by catalyzing H2O2 with AFA under four parameters respectively (the dose of AFA and H2O2, pH and temperature), AFA catalytic mechanism was studied and discussed.Results showed nitric acid is the best one. Under the optimum conditions (pH=2.0, the dose of H2O2 and AFA were 166.5 mg·L-1,10 g·L-1 respectively, reaction time=60 minutes), PNP can be decomposed more than 98%; The results also demonstrated the adsorption amount of PNP by AFA and the amount of PNP oxidized by homogeneous Fenton-like oxidation precesses are just 2.96% and 2.79% respectively. In the catalytic process, the higher AFA load and less reaction time can increase the reutilization times and keep fine catalyst activation.Catalytic kinetics performance of the AFA at pH< 3 exhibited two-period removal rates of p-NP, viz. an initial slow remove period and a following rapid remove period, the reason is that the generation of HO2·and O2·with small oxidation potential in initial period and the generation of HO·whose oxidative capacity is very strong in the followed period. AFA catalytic mechanism has the same processes with Fe3+ homogenious catalytic mechanisms.