School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China.
School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; Key Laboratory of Ministry of Education on Pollution Control and Ecosystem Restoration in Industry Clusters, Guangzhou, 510006, China; Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, Guangzhou, 510006, China.
Chemosphere. 2024 Aug;362:142652. doi: 10.1016/j.chemosphere.2024.142652. Epub 2024 Jun 25.
The simultaneous removal of anionic and cationic heavy metals presents a challenge for adsorbents. In this study, acetate (Ac-) was utilized as the intercalating anion for layered double hydroxide (LDH) to prepare a novel biochar composite adsorbent (Ac-LB) designed for the adsorption of Pb(II), Cu(II), and As(V). By utilizing Ac- as the intercalating anion, the interlayer space of the LDH was enlarged from 0.803 nm to 0.869 nm, exposing more adsorption sites for the LDH and enhancing the affinity for heavy metals. The results of the adsorption experiments showed that the adsorption effect of Ac-LB on heavy metals was significantly improved compared to the original FeMg-LDH modified biochar composites (LB), and the maximum adsorption capacity of Pb(II), Cu(II), and As(V) were 402.70, 68.50, and 21.68 mg/g, respectively. Wastewater simulation tests further confirmed the promising application of Ac-LB for heavy metal adsorption. The analysis of the adsorption mechanism revealed that surface complexation, electrostatic adsorption, and chemical deposition were the main mechanisms of action between heavy metals (Pb(II) and Cu(II)) and Ac-LB. Additionally, Cu(II) ions underwent a homogeneous substitution reaction with Ac-LB. The adsorption process of As(V) by Ac-LB mainly relied on complexation and ion-exchange reactions. Lastly, the modification of the LDH structure by Ac as an intercalating anion, thereby increasing the affinity for heavy metals, was further illustrated using density-functional theory (DFT) calculations.
同时去除阴离子和阳离子重金属对吸附剂来说是一个挑战。在这项研究中，醋酸盐（Ac-）被用作层状双氢氧化物（LDH）的插层阴离子，以制备一种新型的生物炭复合吸附剂（Ac-LB），用于吸附 Pb(II)、Cu(II)和 As(V)。通过利用 Ac-作为插层阴离子，LDH 的层间距从 0.803nm 扩大到 0.869nm，为 LDH 暴露更多的吸附位点，并增强对重金属的亲和力。吸附实验结果表明，与原始 FeMg-LDH 改性生物炭复合材料（LB）相比，Ac-LB 对重金属的吸附效果显著提高，Pb(II)、Cu(II)和 As(V)的最大吸附容量分别为 402.70、68.50 和 21.68mg/g。废水模拟试验进一步证实了 Ac-LB 在重金属吸附方面的应用前景。吸附机制的分析表明，表面络合、静电吸附和化学沉积是重金属（Pb(II)和 Cu(II))与 Ac-LB 之间的主要作用机制。此外，Cu(II)离子与 Ac-LB 发生了均相取代反应。Ac-LB 对 As(V)的吸附过程主要依赖于络合和离子交换反应。最后，利用密度泛函理论（DFT）计算进一步说明了 Ac 作为插层阴离子对 LDH 结构的修饰，从而提高了对重金属的亲和力。
