| 磁性介孔碳负载纳米零价铁的制备及其去除高盐废水中Cr(Ⅲ)有机配合物 | |
| Preparation of magnetic mesoporous carbon loaded nano zero-valent iron for removal of Cr(Ⅲ) organic complexes from high-salt wastewater | |
| 摘要: 采用液相还原法制备了磁性介孔碳(Fe3O4@C)负载纳米零价铁(nano zero-valent iron，nZVI)复合材料(Fe3O4@C-nZVI)，并将其用于高盐水中Cr (Ⅲ)-EDTA (EDTA：乙二胺四乙酸)的去除。扫描电镜、透射电镜、X射线衍射等表征表明nZVI成功负载且分散良好，可磁性分离，在碳层保护下nZVI稳定性强，有利于材料的重复利用。nZVI的加入大大提高了Fe3O4@C-nZVI对Cr (Ⅲ)-EDTA的吸附能力，在pH=4.0、反应温度为25℃时，Fe3O4@C-nZVI对Cr (Ⅲ)-EDTA的最大吸附量为10.24 mg·g-1，显著高于Fe3O4@C (4.31 mg·g-1)。吸附Cr (Ⅲ)-EDTA的过程更符合Langmuir模型和准二级动力学模型。Fe3O4@C-nZVI对Cr (Ⅲ)-EDTA的吸附能力随着溶液pH值的增加先增加后减小；低浓度络合剂(EDTA、柠檬酸)会促进Cr (Ⅲ)-EDTA的吸附，而络合剂浓度增加时则表现为抑制；高浓度阳离子(Na+、K+、Ca2+)会促进Cr (Ⅲ)-EDTA的吸附。Fe3O4@C-nZVI在盐和络合剂环境中对Cr (Ⅲ)-EDTA仍表现出显著的吸附效果。经过3次再生循环后，Fe3O4@C-nZVI对Cr (Ⅲ)-EDTA的吸附量达6.90 mg·g-1。X射线光电子能谱分析表明，Fe3O4@C-nZVI通过表面FeⅢ与Cr (Ⅲ)-EDTA之间的配位作用形成FeⅢ-EDTA-Cr (Ⅲ)配合物从而将Cr (Ⅲ)-EDTA去除，随后通过离子置换作用将Cr (Ⅲ)置换出来，置换出的Cr (Ⅲ)会与表面氧化铁共沉淀为CrxFe1-x(OH)3，进而沉积在nZVI表面被去除。 | |
| 关键词: 磁性介孔碳 纳米零价铁 Cr(Ⅲ) 高盐废水 吸附机制 | |
| 基金项目: 国家自然科学基金(No.22076111)资助。 | |
| Abstract: Magnetically mesoporous carbon (Fe3O4@C)/nano-zerovalent iron (nZVI) composites (Fe3O4@C-nZVI) were successfully prepared by a liquid-phase reduction for the effective removal of Cr(Ⅲ)-EDTA (EDTA: ethylenediaminetetra-acetic acid) in high-salinity wastewater. By characterization and analysis by scanning electron microscope (SEM) and electron microscope (TEM), the nZVI has been successfully loaded into the carbon layer without significant agglomeration and can be magnetically separated and nZVI was stable under the protection of a carbon layer which is favorable for the reuse of materials. The presence of nZVI on the adsorbents greatly improved the adsorption of Cr(Ⅲ)-EDTA and the maximum adsorption capacity of Fe3O4@C-nZVI was 10.24 mg·g-1 at pH=4.0, 25 ℃, which was remarkably higher than that of Fe3O4@C (4.31 mg·g-1). The results showed that the Langmuir model and the pseudo-second-order kinetic model can better describe the adsorption of Cr(Ⅲ)-EDTA by Fe3O4@C-nZVI. The adsorption capacity of Fe3O4@C-nZVI on Cr(Ⅲ)-EDTA increased and then decreased with the increase of solution pH value; low concentrations of complexing agents (EDTA, citric acid) would promote the adsorption of Cr(Ⅲ)-EDTA, whereas an increase in the concentration of the complexing agents showed inhibition; due to the charge shielding effect, high concentrations of cations (Na+, K+, Ca2+) in the solution will promote the adsorption of Cr(Ⅲ)-EDTA. Fe3O4@C-nZVI still showed significant adsorption of Cr(Ⅲ)-EDTA in a salt and complexant environment. The adsorption saturated Fe3O4@C-nZVI was regenerated by 0.1 mol·L-1 HCl solution, the adsorption of Cr(Ⅲ)-EDTA by Fe3O4@CnZVI reached 6.90 mg·g-1 after three regeneration cycles. X -ray photoelectron spectrum analysis of Fe3O4@C-nZVI before and after reaction showed that the adsorption mechanism was mainly through complexation between surface FeⅢ and Cr(Ⅲ)-EDTA to form FeⅢ-EDTA-Cr(Ⅲ) complexation products, and subsequently displaces Cr(Ⅲ) due to ionic displacement, and the displaced Cr(Ⅲ) will be removed by co-precipitation with FeⅢ as CrxFe1-x(OH)3 deposited on the nZVI surface. | |
| Keywords: magnetically mesoporous carbon nano zero-valent iron Cr(Ⅲ) high salinity water adsorption mechanism | |
| 投稿时间：2024-03-11 修订日期：2024-06-29 | |
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| 张元培,王家宏,黄金明,胡智.磁性介孔碳负载纳米零价铁的制备及其去除高盐废水中Cr(Ⅲ)有机配合物[J].无机化学学报,2024,40(9):1731-1742. | |
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