研究报告
谢武明,毕小林,黄子峻,李瑜辉.纳米活性氧化铝负载磁性纳米零价铁对不同重金属的吸附机理[J].环境科学学报,2020,40(8):2732-2740
纳米活性氧化铝负载磁性纳米零价铁对不同重金属的吸附机理
- Adsorption mechanism of different heavy metals on the magnetic nano-zerovalent iron supported by nano-active alumina
- 基金项目：广东省重大科技专项（No.2015B010110004）；广州市产学研协同创新重大专项（No.2014Y2-00214，201704030109）
- 作者
- 单位
- 谢武明
- 广东工业大学环境科学与工程学院, 广州 510006
- 毕小林
- 广东工业大学环境科学与工程学院, 广州 510006
- 黄子峻
- 广东工业大学环境科学与工程学院, 广州 510006
- 李瑜辉
- 广东工业大学环境科学与工程学院, 广州 510006
- 摘要：采用液相还原法将纳米零价铁（nZVI）均匀负载在纳米活性氧化铝（γ-Al2O3）表面和孔道内壁上，制备出磁性纳米零价铁/活性氧化铝复合材料（nZVI/γ-Al2O3）并对其进行了表征，模拟了5种典型重金属离子Zn（Ⅱ）、Cu（Ⅱ）、Cd（Ⅱ）、Cr（Ⅲ）、Mn（Ⅱ）在nZVI/γ-Al2O3上的吸附等温线和动力学，并研究了多元重金属离子体系中竞争吸附和协同吸附行为.结果表明，磁性纳米零价铁负载在纳米活性氧化铝上，不仅克服了因体积效应和表面界面效应所导致的nZVI颗粒团聚，而且使nZVI仍处于稳定的高表面能状态.nZVI/γ-Al2O3复合材料兼具高表面积、高还原性和高表面活性，其对Zn（Ⅱ）、Cu（Ⅱ）、Cd（Ⅱ）、Cr（Ⅲ）、Mn（Ⅱ）离子表现出了良好的吸附性能，单一重金属离子的饱和吸附容量分别为53.0、74.9、114.7、99.1、42.9 mg·g-1.在多元重金属离子体系中5种重金属离子存在竞争吸附和协同吸附作用.当pH为6.67，吸附剂投加量为0.5 g·L-1，各重金属离子初始浓度为10 mg·L-1时，300 min内Cr（Ⅲ）、Cu（Ⅱ）、Zn（Ⅱ）、Mn（Ⅱ）的去除率分别高达99.9%、99.9%、99.9%、81.7%，处理后Cr（Ⅲ）、Cu（Ⅱ）、Zn（Ⅱ）平衡浓度均低于检出限，Mn（Ⅱ）和Cd（Ⅱ）平衡浓度分别为1.9 mg·L-1和6.4 mg·L-1；在多元体系下Zn（Ⅱ）与其他金属离子存在协同吸附，但Cd（Ⅱ）与其他重金属离子存在竞争吸附，其去除率仅为37.7%.因此，nZVI/γ-Al2O3复合吸附材料用于去除废水中典型重金属具有良好的应用前景.
- Abstract：The magnetic nano-zero-valent iron-modified nano-active alumina (nZVI/γ-Al2O3) composite materials were synthesized by chemical reduction method in aqueous solution with nano-zero valent iron (nZVI) being well-integrated on the surface and in the pore walls of activated alumina (γ-Al2O3). The Zn (Ⅱ), Cu (Ⅱ), Cd (Ⅱ), Cr (Ⅲ), and Mn(Ⅱ) isotherms and adsorption kinetics of nZVI/γ-Al2O3 were analyzed, and their competitive and synergistic adsorption mechanisms for the heavy metals in a multicomponent system were also studied. The results showed that the nZVI/γ-Al2O3 keeps in a stable high surface energy state and avoids the agglomeration of nZVI for volume and surface interface effect of nanoparticles. The nZVI/γ-Al2O3 exhibited the high specific surface area, reducibility, and surface activity. Also it showed good adsorption performance for Zn (Ⅱ), Cu (Ⅱ), Cd (Ⅱ), Cr (Ⅲ), and Mn(Ⅱ) in the single adsorption systems with saturation adsorption capacities of 53.0, 74.9, 114.7, 99.1, and 42.9 mg·g-1 respectively. There are competitive and synergistic adsorptions in the multiple heavy metals solution. Under the optimized adsorption conditions with pH 6.67, at the adsorbent dosage of 0.5 g·L-1, the removal rates of Cr (Ⅲ), Cu (Ⅱ), Zn (Ⅱ), and Mn(Ⅱ) were 99.9%, 99.9%, 99.9%, and 81.7%, respectively, under initial concentration of 10 mg·L-1 for each. In addition, under the optimized condition, the equilibrium concentrations after adsorption were lower than the limits of detection, but Mn (Ⅱ) and Cd (Ⅱ) were 1.9 and 6.4 mg·L-1, respectively. Synergistic adsorption effect between Zn (Ⅱ) and coexisting metal ions was observed in the multiple heavy metals system. However, competition adsorption from coexisting metal ions was detected for Cd (Ⅱ) with the removal rate of only 37.7%. The present results suggest that there is a favorable application foreground for the nZVI/γ-Al2O3 composite adsorbent in the removal of typical heavy metals from wastewater.
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