| The soil and groundwater of China domestic chromium chemical industry sites were seriously polluted by chromium,and its remediation is of practical significance.As a risk control technology for groundwater,permeable reactive barrier(PRB)technology requires simple installation,low energy consumption,and low cost,and therefore has been widely applied in groundwater remediation.Due to the various advantages of Zero-valent iron,including simultaneous removal ability for multiple pollutants,environmental friendliness,cheaper price,and easier acess,PRB with filler of zero-valent iron has been widely used in the remediation of Cr(?)contaminated groundwater.However,the surface of zero-valent iron is prone to passivation,leading to a decrease in chromium removal performance,and a reduction in the operating life of iron-based PRB material.In order to develop a PRB material with higher chromium removal capacity and stability.In this paper,a one-pot method was used to modify the iron with coupling modification of iron-copper and sulfidation,and a sulfidated bimetallic material(S-ZVICu)was thereby obtained.The structure of S-ZVICu was revealed,its chromium removal mechanism was investigated,and its application performance was evaluated.The main innovative progresses are summarized as follows:(1)A sulfidated bimetalllic material(S-ZVICu)was prepared by the iron-copper bimetal-sulfide coupling modification of iron powder.Under the optimal preparation conditions,including a sulfidation pH value of 5.4,a sulfidation time period of 2 h,a Cu/Fe mass ratio of 0.0125,and an S/Fe molar ratio of 0.084,the prepared S-ZVICu has a specific surface area up to 8.9 m2·g-1 and a chromium removal capacity as high as 67.5 mg·g-1.Its chromium removal capacity is 54 times higher than that of commercial original iron powder.(2)The structure of prepared S-ZVICu was revealed and its chromium removal mechanism was investigated.The XPS,SEM-EDS and other characterization results exhibited that,the S-ZVICu has a special surface hierarchical structure of Fe0/Cu0/FeSx.Such structure enables S-ZVICu a loose porous surface and a more hydrophilic interface.Combined with Fe(II)masking experiment research,the chromium removal mechanism of S-ZVICu was explained.Cr(VI)is mainly removed by S-ZVICu through reduction,adsorption and precipitation.The Cu0 and FeSx on the surface of S-ZVICu play a dual role in promoting electron transport between the core Fe0 and Cr(VI).(3)Through static and dynamic simulation experiments,the application performance of the prepared S-ZVICu was evaluated.The static simulation experiment results showed that S-ZVICu has a good stability and safety,without secondary pollution risk of Cu(II).Chloride ions in groundwater could help to improve the chromium removal.S-ZVICu has a wide range of pH applications.Under a pH value of 8,its chromium removal efficiency can still reach 99%.In addition,in the co-existence of multiple pollutants,the removal efficiencies of Cr(VI),As(III),V(V)and Pb(II)could reach 99%.The PRB dynamic simulation experiment test results showed that,the higher the influent concentration,the faster the loss rate of Cr(VI)removal performace for S-ZVICu.Compared with the commercial original iron powder,S-ZVICu is capable of saving about 62%in material cost. |
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