Morphologically controlled synthesis of MgFe-LDH using MgO and succinic acid for enhanced arsenic adsorption: Kinetics, equilibrium, and mechanism studies

Yusuf Olalekan Zubair, Shigeshi Fuchida, Keishi Oyama, Chiharu Tokoro*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

In this study, we investigated improving the performance of a layered double hydroxide (LDH) for the adsorption of As(III) and As(V) by controlling the morphology of LDH crystals. The LDH was synthesized via a simple coprecipitation method using barely soluble MgO as a precursor and succinic acid (SA) as a morphological control agent. Doping the LDH crystals with carboxylate ions (RCOO) derived from SA caused the crystals to develop in a radial direction. This changed the pore characteristics and increased the density of active surface sites. Subsequently, SA/MgFe-LDH showed excellent affinity for As(III) and As(V) with maximum sorption densities of 2.42 and 1.60 mmol/g, respectively. By comparison, the pristine MgFe-LDH had sorption capacities of 1.56 and 1.31 mmol/g for As(III) and As(V), respectively. The LDH was effective over a wide pH range for As(III) adsorption (pH 3–8.5) and As(V) adsorption (pH 3–6.5). Using a combination of spectroscopy and sorption modeling calculations, the main sorption mechanism of As(III) and As(V) on SA/MgFe-LDH was identified as inner-sphere complexation via ligand exchange with hydroxyl group (–OH) and RCOO. Specifically, bidentate As-Fe complexes were proposed for both As(III) and As(V) uptake, with the magnitude of formation varying with the initial As concentration. Importantly, the As-laden adsorbent had satisfactory stability in simulated real landfill leachate. These findings demonstrate that SA/MgFe-LDH exhibits considerable potential for remediation of As-contaminated water.

Original languageEnglish
Pages (from-to)637-649
Number of pages13
JournalJournal of Environmental Sciences (China)
Volume148
DOIs
Publication statusPublished - 2025 Feb

Keywords

  • Adsorption
  • Arsenic
  • Bidentate complex
  • Heavy magnesium oxide
  • Layered double hydroxide
  • Stabilization
  • Succinic acid

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • General Environmental Science

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