Stabilization of nanoscale zero-valent iron (nZVI) with modified biochar for Cr(VI) removal from aqueous solution
Stabilization of nanoscale zero-valent iron (nZVI) with modified biochar for Cr(VI) removal from aqueous solution
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DOI：
10.1016/j.jhazmat.2017.03.002
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发表时间：
2017-06-15
影响因子：
13.6
通讯作者：
Zeng, Guangming
中科院分区：
文献类型：
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作者：
Dong, Haoran;Deng, Junmin;Zeng, Guangming
分别对生物质炭进行酸（HCl）处理（HCl-BC）、碱（KOH）处理（KOH-BC）和氧化（H2 O2）处理（H2 O2-BC），制得3种改性生物质炭。制备了生物炭和改性生物炭负载零价铁纳米颗粒（nZVI@BC、nZVI@HCl-BC、nZVI@KOH-BC和nZVI@H2O2-BC），并比较了它们对Cr（VI）的去除能力。结果表明，nZVI@HCl-BC具有最佳的性能，并对其机理进行了讨论。与Cr（VI）反应后的nZVI@HCl-BC表面元素分布图显示，Fe、Cr和O元素均匀沉积在HCl-BC表面，表明所形成的Cr（III）/Fe（III）能够均匀地沉积在HCl-BC表面，而不是仅包覆在nZVI表面。这表明载体HCl-BC也可以起到缓解nZVI钝化的作用。此外，还考察了nZVI/HCl-BC质量比、pH值和Cr（VI）初始浓度对Cr（VI）去除率的影响。在较低质量的HCl-BC，nZVI聚集不能完全抑制在HCl-BC表面，而过量的生物炭可以阻塞nZVI的活性位点。此外，发现通过nZVI@HCl-BC去除Cr（VI）取决于pH和初始Cr（VI）浓度两者。(C)2017 Elsevier B.B. All rights reserved.
Three types of modified biochar (BC) were produced respectively with acid (HCl) treatment (HCl-BC), base (KOH) treatment (KOH-BC) and oxidation (H2O2) treatment (H2O2-BC) of raw biochar. Both the raw biochar and modified biochars supported zero valent iron nanopartilces (nZVI) (i.e. nZVI@BC, nZVI@HCl-BC, nZVI@KOH-BC and nZVI@H2O2-BC) were synthesized and their capacities for Cr(VI) removal were compared. The results showed that the nZVI@HCl-BC exhibited the best performance and the underlying mechanisms were discussed. The surface elemental distribution maps of the nZVI@HCl-BC after reaction with Cr(VI) showed that Fe, Cr and O elements were deposited on the surface of HCl-BC evenly, indicating that the formed Cr(III)/Fe(III) could settle on the surface of HCl-BC uniformly rather than coated only on the nZVI surface. This reveals that the supporter HCl-BC could also play a role in alleviating the passivation of nZVI. Besides, the effects of mass ratio (nZVI/HCl-BC), pH, and initial Cr(VI) concentration on Cr(VI) removal were examined. At lower mass of HCl-BC, nZVI aggregation cannot be fully inhibited on the surface of HCl-BC, whereas excessive biochar can block the active sites of nZVI. Additionally, it was found that Cr(VI) removal by nZVI@HCl-BC was dependent on both pH and initial Cr(VI) concentration. (C) 2017 Elsevier B.B. All rights reserved.