The Role Of Weak Magnetic Field In Accelerating The Removal Of Arsenic By Zero-valent Iron From Groundwater

Arsenic is a metalloid element.Severe exceeding of arsenic has been found in soil and groundwater of most industrial sites.This paper investigated the enhancing effect and mechanism of Weak Magnetic Field?WMF?on arsenic removal by Zero-valent iron?ZVI?through batch tests and column tests.Results of batch test showed that the enhancing effect of WMF on arsenic removal was significant under all pH conditions?5-9?.Especially when initial pH was 7,the rate of reaction increased by 443%(from 0.21 s^-1 to 1.14 s^-1)and removal efficiency increased by 189%?from30.9%to 89.1%?in the presence of WMF.Moreover,the enhancing effect of WMF was more significant by ZVI of smaller particle size?5-9?m?.In addition,we found that in the presence of WMF,more oxygen participated in the reaction,which promoted the corrosion of ZVI and generated more iron oxides and hydroxides.These substances accelerated the adsorption and precipitation of arsenic.The results of SEM and XPS demonstrated this idea.However,the result of column experiment showed that WMF didn't have obvious impact on accelerating the removal of arsenic by zero-valent iron.This is because when the intensity of WMF is too large,ZVI particle can agglomerate together and reduce the effective surface area of ZVI which leads to a decrease of removal efficiency.From the simulation results of column,experimental result and simulated result showed high correlation.In summary,as an effective method to promote arsenic removal by ZVI,WMF is energy-free,chemical-free,environmental-friendly and has a prospective future.However,it should be mentioned that in practical application,it is important to control the intensity of WMF in the effective range.