| 桉树生物炭负载绿色合成纳米零价铁去除水中Cr (Ⅵ) |
| 摘要点击 2518 全文点击 2780 投稿时间：2022-01-25 修订日期：2022-03-04 |
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| 中文关键词 桉树 绿色合成 纳米零价铁 生物炭 Cr(Ⅵ) |
| 英文关键词 Eucalyptus green synthesis nanoscale zero-valent iron biochar Cr(Ⅵ) |
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| 中文摘要 |
| 以桉树叶提取物绿色合成的纳米零价铁（nZVI）为主体，使用桉树生物炭（EBC）负载，成功制备一种高效去除Cr （Ⅵ）的复合材料（EBC-nZVI），考察单一材料和复合材料去除Cr （Ⅵ）的效果差异和循环利用潜力；并研究投加量和溶液初始pH对去除效果的影响.使用GC-MS分析合成前后提取液中成分变化，通过SEM-EDS、FTIR、XRD和XPS对材料表征，结合吸附动力学和吸附等温线实验讨论去除机制.结果表明，绿色合成过程中桉树叶提取液提供了充当还原剂和封端剂的生物分子，复合材料分散性良好并有效缓解nZVI的钝化.复合材料去除Cr （Ⅵ）的过程中EBC和nZVI表现出协同作用，在pH为3，投加量1g·L-1条件下对100mg·L-1的Cr （Ⅵ）溶液去除率达到99.5%以上，且具有良好的循环利用潜力.EBC-nZVI吸附过程符合准二级动力学模型和Langmuir吸附等温模型，活性位点与Cr （Ⅵ）的化学吸附过程是去除速率的主要限制因素.EBC-nZVI与Cr （Ⅵ）的反应机制是nZVI和Fe （Ⅱ）将吸附的Cr （Ⅵ）还原为Cr （Ⅲ），然后通过表面络合、官能团吸附和共沉淀以FeOOH、Fe2O3、Cr （OH）3和Cr2O3的形式实现去除. |
| 英文摘要 |
| A composite material with a high efficiency of Cr(Ⅵ) removal, green synthesis nanoscale zero-valent iron supported on Eucalyptus biochar (EBC-nZVI), was prepared by using Eucalyptus leaf extract-synthesized nanoscale zero-valent iron (nZVI) as the functional body and Eucalyptus sawdust-derived biochar (EBC) as the support material. The difference in Cr(Ⅵ) removal efficiency and recycling potential between the single material and composite material was explored. Some parameters affecting the Cr(Ⅵ) removal were also investigated, including the dosage and initial pH. The changes in components in Eucalyptus leaf extracts before and after synthesis were analyzed using GC-MS. SEM-EDS, FTIR, XRD, and XPS were used to characterize the material, and the removal mechanism was discussed in combination with adsorption kinetics and isothermal adsorption experiments. The results showed that Eucalyptus leaf extracts provided biomolecules as reducing agents and capping agents in the process of green synthesis. The EBC-nZVI had good dispersion and effectively alleviated the passivation of nZVI. EBC and nZVI of composite material displayed a synergistic effect, and the final Cr(Ⅵ) removal percentage was above 99.5% under the following conditions:pH=3, EBC-nZVI dosage of 1 g·L-1, and Cr(Ⅵ) concentration of 100 mg·L-1; the experiments showed that it had good regeneration potential. The adsorption reactions were in line with the pseudo-second order model and Langmuir model, and the main step to limit the adsorption rate was the chemical adsorption process of the active sites with Cr(Ⅵ). The removal mechanism was mainly via the reduction of adsorbed Cr(Ⅵ) to Cr(Ⅲ) by nZVI and Fe(Ⅱ), which then could be removed by surface complexation, functional group adsorption, and co-precipitation in the form of FeOOH, Fe2O3, Cr(OH)3, and Cr2O3. |
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