Catalyzed Oxidation Of P-nitro Phenol Based On Fenton-like Process With Coal Fly Ash

The fly ash in power plants causes many problems, such as environmental pollution and health harm. The research on changing waste into valuables and the full utilization of coal fly ash is in focus. Fly ash has active elements, such as, Fe, Mg, K, Ti, which have also reported on the catalytic effects of fly ash.P-nitro phenol is in the list of 129 priority pollutants of US and 68 priority pollutants of our country because of its toxicity. In order to study the catalytic properties of fly ash, P-nitro phenol was selected as target contaminant.Coal fly ash was investigated as a catalyst on two technical routes in the oxidation of p-nitro phenol with H₂O₂, such as original fly ash and granulated fly ash.The results show that different kinds of coal fly ash have different stucture and composition, which affect its catalytic and adsorption properties. BFA and TFA have almost the same catalytic effects , which COD removal reach 60%.The adsorption effects of BFA is superior to TFA based on its high carbon percent and large specific surface area.Using original fly ash as catalyst, the effects of fly ash composition, pretreatment methods and other parameters (such as dosage, pH, reaction time and oxidant concentration) on PNP removal rate were studied. It was found that acid treatment on fly ash could effectively improve the PNP removal rate. With an initial H₂O₂ concentration of 166 mg/L, 20 g/L acid-treated fly ash could remove99% PNP at 25℃, pH=3 within 20 min.The Fe ion release reduce with reaction times increasing.The removal rate remained at about 99% in the rest 7 rounds of reuse.Using 70% fly ash and 30% attapulgite as catalyst carrier by extrusion process, and loading in iron oxide by impregnation methods to prepare catalyst, the results show that: With an initial H₂O₂ concentration of 166 mg/L, 50 g/L granulated calyst could remove 83% PNP at 25℃,pH=3 within 60 min.Because coal fly ash calyst could produce·OH by hydrogen peroxide in the above two processes,it called Fenton-like Process.