Hydrocolloid liquid-core capsules for the removal of heavy-metal cations from water

A. Nussinovitch*, O. Dagan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

Liquid-core capsules with a non-crosslinked alginate fluidic core surrounded by a gellan membrane were produced in a single step to investigate their ability to adsorb heavy metal cations. The liquid-core gellan-alginate capsules, produced by dropping alginate solution with magnesium cations into gellan solution, were extremely efficient at adsorbing lead cations (267mg Pb2+/g dry alginate) at 25°C and pH 5.5. However, these capsules were very weak and brittle, and an external strengthening capsule was added by using magnesium cations. The membrane was then thinned with the surfactant lecithin, producing capsules with better adsorption attributes (316mg Pb+2/g dry alginate vs. 267mg Pb+2/g dry alginate without lecithin), most likely due to the thinner membrane and enhanced mass transfer. The capsules' ability to adsorb other heavy-metal cations - copper (Cu2+), cadmium (Cd2+) and nickel (Ni2+) - was tested. Adsorption efficiencies were 219, 197 and 65mg/g, respectively, and were correlated with the cation's affinity to alginate. Capsules with the sorbed heavy metals were regenerated by placing in a 1M nitric acid suspension for 24h. Capsules could undergo three regeneration cycles before becoming damaged.

Original languageEnglish
Pages (from-to)122-131
Number of pages10
JournalJournal of Hazardous Materials
Volume299
DOIs
StatePublished - 2015

Bibliographical note

Publisher Copyright:
© 2015 Published by Elsevier B.V.

Keywords

  • Alginate
  • Gellan
  • Heavy-metal cation
  • Liquid-core capsule
  • Protonation

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