腐植酸对nZVI去除水中Cr(Ⅵ)的抑制及抑制作用的消除

The inhibitory role of humic acid on the reduction of Cr(VI) by Fe^0 nanoparticles and the elimination of its inhibitory role

以纳米级零价铁(nZVI)为主要工具修复受污染水体中的Cr(VI),考察了腐植酸(HA)对nZVI去除水中Cr(VI)的抑制作用,并初步探讨了淀粉稳定化nZVI对HA抑制作用的消除.结果表明,随着HA初始浓度由0增加大5,10,15,20,30mg/L,反应10min nZVI对Cr(VI)的去除效率分别达到91.9%,82.6%,78.6%,70.4%,70.0%和69.4%.可见,HA对nZVI去除Cr(VI)的影响是双方面的,一方面,HA会吸附在nZVI的表面,占据nZVI表面的活性反应部位,导致反应速率的下降;另一方面,HA表面带有大量的活性基团,有较大的负电性,会起到一定传递电子的作用,进一步促进反应的进行.由于nZVI的比表面积较大,HA的吸附作用占据主导地位,导致HA的加入对nZVI去除Cr(VI)反应产生明显的抑制作用.适量淀粉(0.5g/L)的加入确实能够起到阻碍nZVI颗粒团聚和HA在nZVI颗粒表面吸附的作用,从而维持nZVI较高的反应活性,消除HA对nZVI去除Cr(VI)的抑制作用.

The reduction of Chromium（VI） by Fe0 nanoparticles（nZVI） was carried out.At the same time,the inhibitory role of humic acid（HA） on the reduction of Cr（VI） by nZVI and the elimination of its inhibitory role by starch were evaluated.Our experimental results indicated that with the initial HA concentration increased from 0 to 5,10,15,20,30 mg/L,the removal efficiencies of Cr（VI） arrived at 91.9 %,82.6 %,78.6 %,70.4 %,70.0 % and 69.4 % in 10min,respectively.Indicating the effects of HA to Cr（VI） reduction by nZVI was dual.On the one hand,HA adsorbed on the surface of nZVI,which would occupy the active surface sites for Cr（VI） reduction and the accumulation of adsorbed HA on the nZVI surface might reduce the Cr（VI） reduction rate.On the other hand,the function in HA might act as electron shuttle promoting electron transfer,this would have a positive effective enhancing the reduction of Cr（VI） by nZVI.Generally speaking,the sorption behaviors of HA on the nZVI particle＇s surface played a dominant role for the nZVI＇s high specific surface areas,which resulted in the inhibitory role of HA on the reduction of Cr（VI） by nZVI.Appropriate content of starch could prevent agglomeration of nZVI and prevent the adsorption of HA on nZVI particles enhancing a state of dispersion which could maintain the reactivity of nZVI.To great extent,the starch addition at a dose of 0.5 g/L could eliminate the inhibitory role of HA.