Analysis Of Iron Form And Process Research In Magnetic Field Enhanced Coagulation-membrane Filtration

The coagulation-membrane filtration process is widely used in the treatment of micro-polluted water.In this study,the effect of magnetization with Fe3O4,coagulant concentration and hydrolysis process on the distribution of Fe(Ⅲ)species was analysed by a timed complexation spectroscopy method and ultraviolet spectroscopy.The effect of the distribution of Fe(Ⅲ)species on the floc properties during coagulation and the membrane fouling in continuous coagulation-membrane filtration process was studied.At first,the effect of magnetization time on the residual magnetic flux density of the magnetic seeds(Fe3O4)suspension and the effect of the residual magnetic flux density on the distribution of Fe(Ⅲ)species were studied.The results showed that the residual magnetic field intensity of magnetic seeds(Fe3O4)changed with their magnetization time from 1 to 10 min in magnetic field intensity of H=200 mT.The magnetization time increases,the residual magnetic field intensity first increases and then decreases.After 3 min of magnetization,the residual magnetic field intensity of magnetic seeds(Fe3O4)research maximum,about 0.78 mT.The residual magnetic field intensity with 9 min was the least,about 0.18 mT.And the residual magnetic field intensity could influence the distributions of Fe(Ⅲ)species.The higher the residual magnetic field intensity,the higher the sum of Fea and Feb(Fea+b)of Fe(Ⅲ)species.Secondly,the effects of the magnetic field-based,hydrolysis process and the concentration on the Fe(Ⅲ)species distribution were analyzed by the timed conplexation spectroscopy method and ultraviolet spectroscopy.The results showed the higher of the concentration,the more dominant the monomer specy(Fea).With the extending of the hydrolysis time of the coagulant solution,it can be seen that the monomer specy is gradually reduced and converted to the high polymer state.It reflects that the hydrolysis process is a process in which an oligomeric state continuously combines with OH-to form a polyhydroxy complex,which eventually leads to a gradual decrease in the oligomeric state and an increase in the high polycondensation state.At the same time,the higher the residual magnetic flux density of the magnetic seeds(Fe3O4)suspension,the higher the proportion of the low polymerization state.The existence the residual magnetic flux density of the magnetic seeds(Fe3O4)suspension inhibits the hydrolysis process of the FeCl3 solution in some extent.Finally,the continuous coagulation-membrane filtration process with direct filtration,coagulant(magnetization time is Omin),magnetization time is 3 min,magnetization time is 9 min was compared,and the economic aspects of magnetization for 3 min and non-magnetization were compared.The experimental results show that the coagulation as a pretreatment method can significantly slow down the membrane fouling.And the greater the proportion of Fea+b in the FeC13 solution,the more favorable flocs with large size and loose structure are formed.The slower the membrane fouling rate,the larger the filtration flux and the higher the filtration efficiency are.The non-magnetization,the lower proportion of the active ingredient Fea+b lead to form small floc size.The structure is compact,and the membrane fouling rate is fast,resulting in lower filtration flux and treatment efficiency.The directly filtering the water cause the fastest membrane fouling.Therefore,coagulation can effectively reduce membrane fouling effestively.By adjusting the distribution of Fe(Ⅲ),increasing the proportion of effective form,membrane fouling can be controlled in the filtration process,which improve filtration efficiency and saving operating expenses.