Preparation Of Fe/Mn/Co Silicate Catalyst And Its Catalysis Of Organophosphorus Pesticide Wastewater Degradated By K₂S₂O₈ Oxidation Technology

In recent years,China's annual output of pesticides exceeded one million tons,with 300 million tons of pesticide wastewater,pesticide wastewater is recognized as one of the difficult industrial wastewater,of which 80% are organophosphorus pesticide wastewater,organic phosphorus pesticide wastewater COD content is very High,up to tens of thousands of mg/L,TP,ammonia,salt,the same high.In this paper,a series of Fe/Mn/Co silicate catalysts were prepared by using sol-gel method,and the composition ratio of the metal elements of the catalyst,the time of ultrasonic treatment,the calcination temperature and other factors on the catalyst activity.The catalysts were characterized by means of surface analyzer,Fourier transform infrared spectroscopy,X-ray diffractometer,X-ray photoelectron spectroscopy,scanning electron microscopy and energy dispersive spectroscopy.The degradation effect of K₂S₂O₈ on the degradation of acephate wastewater and the actual organic phosphorus wastewater was studied under different reaction conditions.The mechanism of the catalyst was analyzed and the following conclusions were obtained:?1?Fe/Mn/Co silicate catalyst was prepared as follows: Fe/Mn/Co 2: 1: 0.2,calcination temperature 400?,ultrasonic 1 h;the catalyst was characterized by the catalyst composition of SiO2NaO·Fe2O3,NaFe?Si O4?2,FeOOH,CoFe2O4-MnFe2O4,belonging to the layered,mesoporous,amorphous materials.?2?Fe/Mn/Co silicate catalyst catalyzed K₂S₂O₈ degradation of 1800mg/L acephate wastewater the best conditions: temperature 35 ?,pH 7,0.8MPa,reaction 1h,K₂S₂O₈ dosage 0.2g/L,catalyst the removal rate of COD was up to 85%,the conversion rate of organic phosphorus was 94%,and the removal rate of methamidophos was 88%.The initial COD concentration of pesticide wastewater was 25000mg/L,TP 4000mg/L,NaCl concentration 6000 mg/L in the COD removal rate of 68%,organic phosphorus conversion rate of 70%.?3?The degradation of pollutants in organophosphorus pesticide wastewater is caused by the oxidation of ·SO4 by K₂S₂O₈ catalyzed by Fe/Mn/Co silicate catalyst.The adsorption capacity of the catalyst to acephate is only 4.9%,while the catalyst has good the removal rate of COD and the conversion rate of organic phosphorus were about 70% and the removal rate of methotrexate was about 55% in 1800mg/L acephate wastewater after 6 times of recycling.?4?Fe,Mn and Co were +3 valence,+ 2 valence,+ 2 valence,respectively,after the reaction of Fe/Mn/Co silicate catalyst before and after the reaction,the reaction was changed to +6,The results show that the three metal elements are involved in the catalytic reaction of K₂S₂O₈,Mn,Co and Fe form MnFe2O4 and CoFe2O4,Mn and Co respectively.The catalyst can distribute more Fe and catalyst on the surface of the catalyst.The reduction ability is enhanced,so that the catalyst has a higher activity.