La-doped MgFe-layered double hydroxides and their sorption properties towards tungsten oxyanions (WO42-) at alkaline pH’s

• Published in: Journal of environmental chemical engineering Vol. 12; no. 2; p. 112196
• Main Authors: Seftel, Elena M., Spooren, Jeroen, Kus, Monika, Cool, Pegie, Michielsen, Bart
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2024
• Subjects: Alkaline stability; Layered double hydroxides; Structural modification by La-doping; WO42- recovery; WO42- recovery; Structural modification by La-doping; Alkaline stability; Layered double hydroxides
• ISSN: 2213-3437; 2213-3437
• DOI: 10.1016/j.jece.2024.112196

The present study focuses on the tungsten recovery from alkaline solutions using for the first time La-doped MgFe-LDH type sorbents (pH ≥ 13). A small-scale synthesis procedure was optimized, and further upscaled (20x) to produce up to 200 g batches with reproducibility degree close to 100%. The chemical composition, structural and textural characteristics of the as-synthesized materials were investigated by ICP-OES, X-ray Diffraction, N2 physisorption and IR spectroscopy techniques. The materials were applied for sorption of WO42- anions in aqueous media under relevant conditions. Parameters influencing the sorption process, such as the LDH composition, pH of the sorption media, adsorption capacity, kinetics and desorption solution composition were thoroughly investigated. Multi-cycling tests in different desorption solutions combined with IR and XRD characterization of the La-MgFe-LDH solids in different steps of the process, allowed us to elucidate the WO42- recovery mechanism. Further, the La-doping in the LDH structure increases the sorption capacity and assures the material stability throughout the WO42- recovery process in high pH media. The alkaline stability was demonstrated by powder post characterization by X-ray Diffraction as well as performing alkaline stability test and follow up of any leaching elements by ICP-OES in alkaline solutions. The results indicate that the as-developed La-MgFe-LDH are suitable candidates for WO42- recovery from aqueous solutions, including highly alkaline solutions compatible with the current hydrometallurgical processes. •La-doped LDHs are used for the first time for WO42- recovery from alkaline streams.•La-doping in the LDH structure increases the sorption capacity.•La-doping in the LDH structure assures the material stability in high pH media.•Small-scale synthesis of La-doped LDHs is upscaled successfully (20x).•Sorption mechanism is revealed via characterization after WO42-adsorption.