柠檬皮渣负载纳米零价铁去除搬迁厂厂区土壤中铬污染

Removal of Chromium Pollution from Soil of Relocation Plant by Nano-zero-valent Iron Loaded on Lemon Peel Residue

通过制备柠檬皮渣生物活性炭,利用液相还原法,负载上纳米零价铁(nZVI),有效解决nZVI在土壤中铬污染处理中自身团聚问题,提高Cr(VI)的去除率。研究发现,当碳铁质量比为1.25︰1,生物活性炭携载纳米零价铁(nZVI/AC)对土壤Cr(VI)去除率达60.3%。SEM和能谱分析表明,nZVI/AC比纯纳米零价铁更好的分散性,nZVI均匀分布活性炭表面,有效减少铁的团聚。当p H在3~9,随着p H的降低,去除率升高。在p H小于3时,观察到最高的去除效率。反应温度的升高对于提高n ZVI/AC去除溶液中Cr(VI)反应速率贡献有限。吸附动力学符合准二级动力学模型,说明n ZVI/AC对于Cr(VI)的去除主要受化学吸附过程控制。

In order to solve the problem of self-aggregation and improve the removal rate of Cr(VI) in the treatment of Cr pollution in soil, the bioactivated carbon from lemon peel residue was prepared and loaded with nano-sized zero-valent iron(nZVI) by liquid-phase reduction method. When the mass ratio of carbon to iron was 1.25︰1, the removal rate of Cr(VI) carried by nano-scale zero-valent iron(nZVI/AC) was 60.3 %. SEM and energy spectrum analysis show that nZVI/AC has better dispersibility than pure nanosized zero-valent iron, and nZVI distributes the surface of activated carbon evenly, thus effectively reducing the agglomeration of iron. When pH was 3~9, the removal rate increases with the decrease of pH. The highest removal efficiency was observed when pH was less than 3.The increase of reaction temperature had limited effect on the removal rate of Cr(VI) from nZVI/AC solution. The kinetics of Cr(VI) removal by nZVI/AC was mainly controlled by the chemical adsorption process.