Insight into different removal behaviors and mechanism of heavy metals via sulfate-loaded layered double oxide. Issue 3 (June 2022)

• Record Type: Journal Article
• Authors: Zhang, Ping; Wang, Wenjun; Liu, Wen; Li, Peng; Cai, Yue; Chen, Jincheng; Ding, Nengshui
• Is Part Of: Journal of environmental chemical engineering. Volume 10:Issue 3(2022)
• Publication Date: 2022-06
• Subjects: Heavy metals -- Different adsorption capability -- Sulfate-loaded layered double oxide -- Adsorption mechanism; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2022.107751
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: Sulfur-containing materials with high affinity toward heavy metals have recently aroused great research enthusiasm. Yet the removal differences and mechanisms for various heavy metals remain unclear in view of rarely systematical reports. In this regard, a sulfate-loaded adsorbent (MgAl-LDO@S) synthesized by precursor-calcination strategy was employed for investigating the removal differences of heavy metals (i.e ., Pb(Ⅱ), Cd(Ⅱ) and Ni(Ⅱ), typical heavy metals in wastewater). As predicted, a diverse adsorption capability for metals on MgAl-LDO@S was observed, following the order of Pb(Ⅱ) (631.90 mg g −1 ) > Cd(Ⅱ) (208.27 mg g −1 ) > Ni(Ⅱ) ( 1 19.02 mg g −1 ). Both adsorption isotherm and kinetic demonstrated that the monolayer, heterogeneous-homogeneous, and multilayer adsorption occurred in Pb(Ⅱ), Cd(Ⅱ) and Ni(Ⅱ), respectively, which were controlled by chemisorption. Furthermore, the removal differences were deeply exploded via the combination of XRD, FT-IR and XPS analyses and contribution calculation. The ion exchange was the main adsorption mechanisms for Pb (II) with 44.77%, while complexation dominated in Cd(II) and Ni(II) removal, with the proportion of 53.36% and 55.89%, respectively. Besides, the solubility constant ( K sp ) of precipitate, affinity of sulfate group, as well as the self-characteristic properties contributed to various removal ability for heavy metal ions (e.g., ionic radius, electronegativity, and hard-soft-acid-base attribute) as well. Graphical Abstract: ga1 Highlights: A sulfate-loaded layered double oxide was prepared via precursor-calcination strategy. The metals adsorption ability followed the order of Pb(II)> Cd(II)> Ni(II). Different mechanisms were identified as precipitation, surface complexation and ion exchange. The differences were associated with the K sp of precipitation and characteristics of metals.