Treatment Of P-Nitrophenol Wastewater By Photo-assisted Heterogeneous Fenton Process

In order to solve the problems such as the low utilization rate of H2O2 by convent ional Fenton method,the small application range of reaction pH,the difficulty in recycl ing the catalyst,and the increase of the chroma of the solution by ferric ion,the hetero geneous Fenton method attracts people's attention.The purpose of this paper is to study the heterogeneous Fenton catalyst,Fe-Ce/Al2 O3,which is difficult to degrade organic p-nitrophenol(PNP)as the target pollutant.Un der the combined action of light and catalyst,the purpose of removing PNP in water is achieved.The effect of catalyst concentration and catalyst concentration on the perform ance of the catalyst was studied.The influence of catalyst preparation conditions on the catalyst characteristics and treatment efficiency was investigated.The catalytic mechanis m of the catalyst was analyzed and the influence of the heterogeneous Fenton system o n the PNP wastewater was studied.Influence factors,and finally get a catalyst with go od catalytic performance.The optimal preparation conditions of heterogeneous catalysts were as follows:25g of activated Al2O3 particles were placed in 100mL of 0.3 mol/L Fe(NO3)3 solution,The mixed solution of Ce(NO3)3 and oxalic acid(30%of Ce(NO3)3 and 0.3%of oxalic aci d)was immersed in a constant temperature water bath at 25 ? for 25h,then heated in water bath.Washed with deionized water,filtered,dried in an oven at 105?,and calcin ed at 350? for 3 hours to obtain a supported Fe-Ce/Al2O3 catalyst.The BET specific s urface area of the Fe-Ce/Al2O3 catalyst was 228.92m2/g,the total pore volume was 0.41 cm3/g,and the average pore size was 4.56nm.The catalyst had a rich pore structure on thecatalyst surface.In this experiment,the heterogeneous photo-assisted Fenton method was used to tre at p-nitrophenol wastewater.The process was carried out by using Fe-Ce/Al2O3 as cataly st and H2O2 as oxidant,and the degradation of PNP wastewater under ultraviolet light e ffect.The optimum conditions of 100mL 200mg/L PNP wastewater were as follows:the loading amount of Fe-Ce/Al2O3 was 100g/L,the dosage of H2O2 was 150mmol/L,the initial pH value was 4,The removal rate reached 98.7%,COD removal rate increased t o 72.9%.In the stability test of the catalyst,the Fe-Ce/Al2O3 catalyst has a good repeat ability in the heterogeneous Fenton system.The catalytic activity of the catalyst remaine dgood after 5 times of reaction.The first-order kinetic equation of degradation of p-nitrophenol wastewater by heter ogeneous photocathode Fenton method was studied.The reaction rate constants increased first and then decreased at different temperatures,H2O2 and catalyst dosage.The reacti on rate constant decreases with increasing pH or initial PNP concentration at different p H and PNP initial concentrations.The heterogeneous Fenton-treated PNP was chosen as the research object,and inorg anic ions commonly found in water were selected to study the effect of these ions on t he heterogeneous Fenton reaction.The influence of the PNP removal rate on the catalyt ie activity was investigated.On the deep research,the S2-on heterogeneous Fenton catal yst for the oxidation of PNP solution is the most obvious effect.H2PO4-,Cl-,H2CO3,S O42-ions all inhibited the PNP solution with heterogeneous Fenton catalyst,and the inhi bition degree was H2PO4->SO42->Cl->H2C03,N032-?Ca2+?K+ and Mg2+ had little eff ect on the degradation of PNP and did not affect the catalytic performance of heterogen eous Fenton catalysts.