Research On Magnetic Flocculation-membrane Filtration Process Based On Iron Speciation Analysis

Magnetically enhanced flocculation ultrafiltration?MEF-UF?has successfully adopted in micro-polluted water treatment processes.In this study,the effects of magnetize methods on Fe?III?species distribution was analyzed,for exploring the mechanism of membrane fouling reduction via magnetically enhanced coagulation.The effects of magnetization on Fe?III?species,coagulation performance,and floc properties were investigated to explore the reason of membrane fouling reduction in MEC-UF processes.The residual magnetic field intensity of magnetic seeds?Fe3O4?changed along with their magnetization times from 1 to 10 min.After 4 min magnetization in magnetic field intensity of H = 0.2 T,the residual magnetic field intensity of magnetized seeds?Fe3O4?was the most?0.92 mT?.The results showed that the magnetized seeds could influence the distributions of Fe???species due to their residual magnetic field intensity after magnetization,the same conclusion was acquired about the relationship through the hydrolysis products of Fe???affected by the Fe3O4 suspension at various magnetization times.The magnetized Fe3O4 suspension not only affected the sum of Fea and Feb of Fe????especially Fea?,but increased the quantity of particles in the micro-polluted water.The Fea and Feb content of Fe???could up to 92.9%after affected by Fe3O4 particles with 4 min magnetization.Therefore,the flocs were much larger with higher strength factor and higher recovery factor,the coagulation performance was better and the cake layers of less compressible were looser and more porous,which was good for membrane fouling reduction.This leads to a better knowledge about magnetically enhanced coagulation on membrane fouling reduction from the perspective of magnetized particles could have an influence on Fe???species distribution.Regular FeCl₃,magnetized FeCl₃,FeCl₃ combined with Fe3O4 and FeCl₃ combined with magnetized Fe3O4 were investigated by comparing their Fe???species distribution,in order to analysis the effects of magnetized methods in MEC-UF processes.Results showed that Fea and Feb contents of FeCl₃ increased after direct magnetization via magnetic field was much higher than those of affected by magnetized Fe3O4 seeds.FT-IR analysis indicated that both of them had a great influence on chemical bonds?between-Fe-and-O-/-OH-?of FeCl₃.The TMP increased most slowly and zeta potential of fouled membrane was lowest in MEC-UF process by addition magnetized Fe3O4 seeds.The magnetized Fe3O4 seeds could play a part in improving contents of Fea and Feb and chemical bonds in FeCl₃.The addition of magnetized Fe3O4 seeds not only increased particles amount,but functioned as coagulation core and adsorbed more pollutants.In a word,the combination of FeCl₃ with magnetized Fe3O4 was the best coagulant to membrane fouling reduction in MEF-UF processes.