Zeng Xiangchu, Zhang Guanghua, Zhu Junfeng
Shaanxi Key Laboratory of Chemical Additives for Industry, Shaanxi University of Science and Technology, Xi'an, Shaanxi, 710021, PR China.
J Environ Manage. 2022 Jul 15;314:114979. doi: 10.1016/j.jenvman.2022.114979. Epub 2022 Apr 19.
The development of adsorbents to remove heavy metal ions from water with recyclable, high adsorption capacity, strong selectivity, safe, and economic performances has always been the focus and challenge of current research. A hyper-branched magnetic composite material (FeO@SiO-S) was fabricated by a method combining "grafting,", "branching," and "modification,", and the structure was characterized by FTIR, XRD, SEM, TEM, SAED, VSM, TGA, and BET. In addition, the adsorption performance and mechanism for heavy metal ions in water were studied. The as-prepared composite material had excellent selective absorbability for Hg, Cd, and Ag in the presence of Fe, Fe, Cu, Mn, CO, Zn, and Ni, and when pH = 6, T = 30 °C, t = 4 h, it reached a saturated adsorption capacity of 2.42, 2.18, and 1.94 mmol/g to Hg, Cd, and Ag, respectively. The adsorption isotherm was consistent with the Langmuir isotherm adsorption model, and the Dubinin Redushcke (D-R) model identified that the adsorption was chemical adsorption in nature. The adsorption kinetic followed the pseudo-second-order model and Boyd film diffusion models. The adsorption capacity of as-prepared material remained about 83% after five elutions. The adsorption mechanism and selective adsorption were revealed by FTIR, EDS, XPS, and DFT calculation. N atoms and O atoms of the active functional groups complexed with metal ions to form stable 2 heptachate chelates and 1 tridentate chelate to achieve the effect of adsorption; furthermore, the adsorption was mainly governed by N atoms of Schiff base groups. This work not only explored an innovative method for the construction of adsorbing materials but also provided a promising adsorbent to selectively remove heavy metal ions in water with potential application.
开发具有可回收、高吸附容量、强选择性、安全且经济性能的用于去除水中重金属离子的吸附剂一直是当前研究的重点和挑战。通过“接枝”、“支化”和“改性”相结合的方法制备了一种超支化磁性复合材料（FeO@SiO-S），并通过傅里叶变换红外光谱（FTIR）、X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、选区电子衍射（SAED）、振动样品磁强计（VSM）、热重分析（TGA）和比表面积分析（BET）对其结构进行了表征。此外，还研究了该复合材料对水中重金属离子的吸附性能及吸附机理。所制备的复合材料在Fe、Fe、Cu、Mn、Co、Zn和Ni存在的情况下，对Hg、Cd和Ag具有优异的选择性吸附能力，当pH = 6、温度T = 30°C、时间t = 4 h时，对Hg、Cd和Ag的饱和吸附容量分别达到2.42、2.18和1.94 mmol/g。吸附等温线符合朗缪尔等温吸附模型，杜宾宁-拉杜舍维奇（D-R）模型表明吸附本质上是化学吸附。吸附动力学遵循准二级模型和博伊德膜扩散模型。经过五次洗脱后，所制备材料的吸附容量仍保持约83%。通过FTIR、能谱分析（EDS）、X射线光电子能谱（XPS）和密度泛函理论（DFT）计算揭示了吸附机理和选择性吸附。活性官能团的N原子和O原子与金属离子络合形成稳定的2个七齿螯合物和1个三齿螯合物，以实现吸附效果；此外，吸附主要受席夫碱基团的N原子控制。这项工作不仅探索了一种构建吸附材料的创新方法，还提供了一种有前景的吸附剂，可选择性去除水中的重金属离子，具有潜在的应用价值。
