Mechanistic insights into soil heavy metals desorption by biodegradable polyelectrolyte under electric field. (1st January 2022)

• Record Type: Journal Article
• Authors: Wang, Yuchen; Li, Ang; Ren, Binqiao; Han, Zijian; Lin, Junhao; Zhang, Qiwei; Cao, Tingting; Cui, Chongwei
• Is Part Of: Environmental pollution. Volume 292:Part A(2022)
• Publication Date: 2022-01-01
• Subjects: Electrokinetic technology -- Divalent heavy metals -- Alginate -- DFT; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2021.118277
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: In this study, we firstly used alginate to enhance an electrokinetic technology to remediate soil contaminated with divalent heavy metals (Pb 2+, Cu 2+, Zn 2+ ). The mechanisms of alginate-associated migration of metal ions in electric field were confirmed. Alginate resulted in a high electrical current during electrokinetic process, and soil conductivity also increased after remediation. Obvious changes in both electroosmotic flow and soil pH were observed. Moreover, these factors were affected by increasing alginate dosage. The highest Cu (95.82%) and Zn (97.33%) removal efficiencies were obtained by introducing 1 wt% alginate. Alginate can desorb Cu 2+ and Zn 2+ ions from soil by forming unstable gels, which could be dissociated through electrolysis. However, Pb 2+ ions did not easily migrate out of the contaminated soil. The density functional theory (DFT) calculations show Pb 2+ ions could form a more stable coordination sphere in metal complexes than Cu 2+ and Zn 2+ ions. The metal removal efficiency was decreased by increasing alginate dosage at a high level. More alginate could provide more carboxyl ligands for divalent metal ions to stabilize gels, which were difficult to dissociate by electrolysis. In summary, the results indicate it is potential for introducing alginate into an electrokinetic system to remediate Cu- and Zn- contaminated soil. Graphical abstract: Image 1 Highlights: Alginate can improve EKR efficiency for Cu 2+ and Zn 2+ contaminated soil. Alginate can desorb metal ions from soil by forming gels. Mechanistic insights into metal desorption were discussed by DFT calculations. Pb 2+ can form stable metal gels which were difficult to electrolysis.