Preparation of stable alginate microcapsules coated with chitosan or polyethyleneimine for extraction of heavy metal ions

Mohammad Outokesh, Hitoshi Mimura, Yuichi Niibori, Kouichi Tanaka

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

Stable alginate microcapsules in dried form containing bis(2,4,4-trimethylpentyl) monothiophosphinic acid (HA) were prepared by coating of fresh alginate microcapsules with chitosan or polyethyleneimine (PEI). The thickness of coatings was estimated by electron probe microanalysis (EPMA), along with electron microscopy (SEM), as well as comparison of uptake percentage of coated and uncoated hollow capsules. Characterization of microcapsules was carried out by Ag+ uptake experiments, destructive chemical analyses and thermogravimetric methods (TG and DTA). Chemical stability tests in HNO3 and NaNO3 media indicated that the coating with 4-double layer chitosan or mono-layer PEI led to an appreciable enhancement of impermeability in the range of pH > 1or [Na+] < 1 M (mol dm-3). Unfortunately, multiple coating causes some extractant losses due to effect of physical stress during the coating; however, PEI-coated microcapsules nearly completely hold their extractant content. Stable extractive microcapsules have an appreciable potential for the selective removal of heavy metal ions.

Original languageEnglish
Pages (from-to)291-301
Number of pages11
JournalJournal of Microencapsulation
Volume23
Issue number3
DOIs
Publication statusPublished - 2006 May 1

Keywords

  • Alginate microcapsules
  • Chitosan
  • Coating thickness
  • Extractant content
  • Impermeability
  • Polyethyleneimine

ASJC Scopus subject areas

  • Bioengineering
  • Pharmaceutical Science
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Colloid and Surface Chemistry

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