Uptake of arsenate by an alginate-encapsulated magnetic sorbent: Process performance and characterization of adsorption chemistry

Soh Fong Lim, Yu Ming Zheng, Shuai Wen Zou, J. Paul Chen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

Arsenate removal by a calcium alginate-encapsulated magnetic sorbent was studied. The morphology, microstructure, and composition properties of the sorbent were explored using X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). The SEM study demonstrates that there are many protuberances and pores on the sorbent surface; the XRD analysis reveals that the sorbent consists of Fe3O4. The EDX analysis indicates that the adsorption on the surfaces of sorbent is highly location dependent. The interaction characteristics between the arsenic and the functional groups on the sorbent were studied by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). These studies indicate that the lattice oxygen in magnetite and the oxygen in hydroxyl of the calcium alginate play important roles in the sorption of arsenate ions onto the sorbent. More importantly, the XPS analysis demonstrates that the arsenate is reduced to arsenite after its adsorption onto the sorbent. It is proposed that divalent iron and the alcoholic group in alginate provide electrons to arsenate. A conceptual model for the adsorption is proposed to illustrate the mechanisms.

Original languageEnglish
Pages (from-to)33-39
Number of pages7
JournalJournal of Colloid and Interface Science
Volume333
Issue number1
DOIs
StatePublished - 1 May 2009
Externally publishedYes

Keywords

  • Adsorption
  • Arsenate
  • Arsenite
  • Calcium alginate-encapsulated magnetic sorbent
  • Reduction

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