同时去除阴离子和阳离子重金属对吸附剂提出了挑战。在这项研究中,利用乙酸盐(Ac-)作为层状双氢氧化物(LDH)的嵌入阴离子,制备了一种新型生物炭复合吸附剂(Ac-LB),Cu(II),As(V)。通过利用Ac-作为嵌入阴离子,LDH的层间空间从0.803nm扩大到0.869nm,暴露更多的LDH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明显提高,和Pb(II)的最大吸附容量,Cu(II),As(V)分别为402.70、68.50和21.68mg/g,分别。废水模拟试验进一步证实了Ac-LB在重金属吸附中的应用前景。吸附机理的分析表明,表面络合,静电吸附,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进行均相取代反应。Ac-LB对As(V)的吸附过程主要依靠络合和离子交换反应。最后,通过Ac-作为嵌入阴离子对LDH结构的修饰,从而增加对重金属的亲和力,使用密度泛函理论(DFT)计算进一步说明。
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.