Removal Of Pollutants In Water By Magnetic Field Enhanced PRB Reaction System

Zero-valent iron is easily passivated,which results in poor reactivity.The magnetic field was used to strengthen it to improve its efficiency in removing pollutants.Dye reactive brilliant red X-3B and the more toxic Se(?)were selected as the target pollutants.Zero valent iron and quartz sand mixture,zero-valent iron and zeolite mixture,zero-valent iron and bentonite mixture,zero-valent iron and activated carbon mixture were used as PRB reaction medium,respectively.The magnetic field was external to the reactor.The performance of the magnetic field-enhanced zero-valent iron permeable reaction barrier(ZVI-PRB)to remove reactive brilliant red X-3B and hexavalent selenium(Se(?))were investigated.Results were as follows:(1)The performance of removal of reactive brilliant red X-3B by magnetic field-enhanced zero-valent iron PRB was investigatd,a mixture of zero-valent iron and quartz sand was used as PRB reaction media,and continuous flow experiments were carried out under different operating conditions.The results showed that the removal effect of Reactive Brilliant Red X-3B increased with increasing p H;adjusting the ratio of the PRB reaction medium,it was found that the higher dosage of zero-valent iron,the better the removal efficiency of Reactive Brilliant X-3B.Further examining the effect of different active brilliant red X-3B concentrations on PRB,it was found that the lower the concentration,the better the removal efficiency.During the experiment,it was found that zero-valent iron was gradually consumed in PRB.SEM and XRD tests were performed on the filled filler after the reaction.It was found that the remaining material was mainly a small amount of iron oxide and unreacted quartz sand.Although the removal law was the same between with and without the magnetic field,the removal efficiency with the magnetic field is generally better than that without the magnetic field.Therefore,the magnetic field can effectively strengthen the zero-valent iron PRB to remove active brilliant red X-3B.(2)The performance of Se(?)removal by magnetic field-enhanced zero-valent iron PRB was investigated,a mixture of zero-valent iron and quartz sand was used as the PRB reaction medium,and continuous flow experiments were conducted under different operating conditions.The results showed that the removal effect of Se(?)increased with the increasing of p H.adjusting the proportion of PRB reaction medium,the higher dosage of zero-valent iron in the reaction medium,the better the removal efficiency of Se(?).The effect of different Se(?)concentrations on PRB was investigated further,it was found that the lower the Se(?)concentration,the better the removal efficiency.It was found that zero-valent iron was gradually consumed in PRB with time elapsing.SEM and XRD tests were performed on the filled filler after the reaction.It was found that the remaining material was mainly a small amount of iron oxide and unreacted quartz sand.Although the removal law was the same between with and without the magnetic field,the removal efficiency with the magnetic field is generally better than that without the magnetic field.Therefore,the magnetic field can effectively strengthen the zero-valent iron PRB to remove Se(?).(3)The performance of active brilliant red X-3B and Se(?)removal under different reaction medium conditions by magnetic field-enhanced zero-valent iron PRB were also investigated.The PRB reaction medium were Zero valent iron and quartz sand mixture,zero-valent iron and zeolite mixture,zero-valent iron and bentonite mixture,zero-valent iron and activated carbon mixture,respectivly.At p H =4,the ratio of ZVI&quartz sand,ZVI&zeolite,ZVI&bentonite,ZVI&activated carbon was 1:20 respectivly,active brilliant red X-3B concentration is 3 mg/L,and the Se(?)concentration was 1 mg/L.The results showed that various reactive media can effectively remove active brilliant red X-3B and Se(?),and the removal efficiency were ranked from low to high as below,zero-valent iron and quartz sand mixture<zero-valent iron and bentonite mixture <zero-valent iron and Zeolite mixture <zero valent iron and activated carbon mixture.Although the removal law was the same between with and without the magnetic field,the removal efficiency with the magnetic field is generally better than that without the magnetic field.Therefore,the magnetic field can effectively strengthen the zero-valent iron PRB to remove reactive brilliant red X-3B and Se(?)under different reaction medium conditions.