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Weak magnetic field accelerates chromate removal by zero-valent iron
Weak magnetic field（WMF） was employed to improve the removal of Cr（VI） by zero-valent iron（ZVI） for the first time. The removal rate of Cr（VI） was elevated by a factor of 1.12-5.89 due to the application of a WMF, and the WMF-induced improvement was more remarkable at higher Cr（VI） concentration and higher p H. Fe2＋was not detected until Cr（VI） was exhausted, and there was a positive correlation between the WMF-induced promotion factor of Cr（VI） removal rate and that of Fe2＋release rate in the absence of Cr（VI） at pH 4.0-5.5. These phenomena imply that ZVI corrosion with Fe2＋release was the limiting step in the process of Cr（VI） removal. The superimposed WMF had negligible influence on the apparent activation energy of Cr（VI） removal by ZVI, indicating that WMF accelerated Cr（VI）removal by ZVI but did not change the mechanism. The passive layer formed with WMF was much more porous than without WMF, thereby facilitating mass transport. Therefore,WMF could accelerate ZVI corrosion and alleviate the detrimental effects of the passive layer, resulting in more rapid removal of Cr（VI） by ZVI. Exploiting the magnetic memory of ZVI, a two-stage process consisting of a small reactor with WMF for ZVI magnetization and a large reactor for removing contaminants by magnetized ZVI can be employed as a new method of ZVI-mediated remediation.
Weak magnetic field accelerates chromate removal by zero-valent iron
Weak magnetic field（WMF） was employed to improve the removal of Cr（VI） by zero-valent iron（ZVI） for the first time. The removal rate of Cr（VI） was elevated by a factor of 1.12-5.89 due to the application of a WMF, and the WMF-induced improvement was more remarkable at higher Cr（VI） concentration and higher p H. Fe2＋was not detected until Cr（VI） was exhausted, and there was a positive correlation between the WMF-induced promotion factor of Cr（VI） removal rate and that of Fe2＋release rate in the absence of Cr（VI） at pH 4.0-5.5. These phenomena imply that ZVI corrosion with Fe2＋release was the limiting step in the process of Cr（VI） removal. The superimposed WMF had negligible influence on the apparent activation energy of Cr（VI） removal by ZVI, indicating that WMF accelerated Cr（VI）removal by ZVI but did not change the mechanism. The passive layer formed with WMF was much more porous than without WMF, thereby facilitating mass transport. Therefore,WMF could accelerate ZVI corrosion and alleviate the detrimental effects of the passive layer, resulting in more rapid removal of Cr（VI） by ZVI. Exploiting the magnetic memory of ZVI, a two-stage process consisting of a small reactor with WMF for ZVI magnetization and a large reactor for removing contaminants by magnetized ZVI can be employed as a new method of ZVI-mediated remediation.
Weak magnetic field accelerates chromate removal by zero-valent iron
2015
Article (Journal)
English
表观活化能 , Cr（VI） , WMF , Iron - chemistry , 正相关关系 , 释放速率 , 加速腐蚀 , 零价铁 , Water Pollutants, Chemical - chemistry , Chromates - chemistry , 弱磁场
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