Study On Synthesis Of Metal Organic Frameworks MIL-88A Targeting Materials And Activate PS On Refractory Organic Pollutants Removel In Water

Metal-organic frameworks?MOFs?is a new porous material composed of inorganic metal nodes and organic ligands.Because of its large specific surface area,controllable pore size,diversity of structure and high chemical corrosion resistance,MOFs has a wide application prospect in catalysis and adsorption.Therefore,it is of great significance to study the porous materials such as MOFs for the removal of the refractory pollutants.In this study,MOFs's MIL series MIL-88A was the research emphasis.Using MIL-88A as the catalyst,OG and DBP as the target pollutants,applying the production of sulfate radicals by catalytic activated persulfate?PS?.The effects of the ratio of raw materials,synthesis time and temperature,drying time and temperature on the adsorption and catalytic performance of MIL-88A were investigated and the best preparation conditions for MIL-88A are obtained that was:the ratio of raw materials n?Fecl₃?6H₂O/Fumaric acid?=1:1,the synthesis temperature T=85,the crystallization time t=2h,the activation temperature T=100,the drying time is 10h.Using MIL-88A which produced at the best preparation conditions as the catalyst,the influence of environmental conditions on the catalytic reaction were considered and it was found that the catalytic reaction could exhibit strong catalytic performance only under acidic conditions.At the same time,the main reasons for the best catalytic activity of MIL-88A&St-3/MIL-88A&Ct-2 were the high specific surface area,more content of Fe dissolution and large particle size which were proved by the experiment.Fumaric acid,one of the raw materials of MIL-88A,could inhibit and promote the catalytic reaction when the content of fumaric acid is different.Through the filtrate experiment,it was concluded that the catalytic reaction involves homogeneous and heterogeneous,but the homogeneous reaction played the leading role and the homogeneous reaction was assisted to activate.Thus,the possible reaction mechanism of this catalytic reaction was obtained.Using MIL-88A as a precursor,the modified target material MIL-88A@MIP,which used DBP as a template molecule,was produced by molecularly imprinted method and applied in activating PS to degradate Phthalates Acid Esters.It was concluded through experiments that the best reaction conditions were:the molar ratio n?PS:DBP?=600:1,the dosages of MIL-88A@MIP was 0.5g/L and Initial pH=3.26.Besides,the intermediates were determined by GC-MS and based on these intermediate products and theoretical analysis,the possible mechanism and course of DBP degradation were proposed.It was pointed out that the main site of DBP attack by free radicals was the ester bond of its branched chain rather than the benzene ring.And hydrogen abstraction,decarboxylation and hydroxylation were the main mechanisms of DBP degradation.