Adsorption of divalent metal ions by succinylated and oxidized corn starches

D. K. Kweon, J. K. Choi, E. K. Kim, Seung Taik Lim

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165 Citations (Scopus)

Abstract

Corn starch was succinylated (degree of substitution, DS 0.03-0.07) with succinic anhydride in an aqueous alkaline medium (pH 10), or oxidized (DS 0.13-0.29) with sodium hypochlorite in the presence of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and sodium bromide, and the adsorption properties of the starches for Cu 2+, Zn 2+, Pb 2+, and Cd 2+ in their aqueous salt solutions were investigated under various conditions. Regardless of the metal type, the adsorption capacity of both ionic starches reached a state of equilibrium within 5-10 min for starch dispersion in metal solutions. The succinylated starch was most effective in binding Pb 2+, whereas the oxidized starch was effective for Cu 2+ among the tested metal ions. Cd 2+ was least effective in binding either to the succinylated or to the oxidized starch. However, the oxidized starch was partially soluble in aqueous solutions, and thus the starch dissolution resulted in reduced metal-adsorption efficiency. The metal-adsorption of both ionic starches followed the Langmuir adsorption isotherm. The maximum adsorption capacity (Q) and Langmuir constant (b) for a succinylated starch (DS 0.07) for Pb 2+ were 0.534 mmol g -1 and 2.276 × 10 -3 ppm -1, respectively. These values were higher than those of Cu 2+, Zn 2+, and Cd 2+. The Q and b values for an oxidized starch (DS 0.29) for Cu 2+ were significantly higher (1.245 mmol g -1 and 14.98 × 10 -3 ppm -1, respectively) than those of Pb 2+, Zn 2+, and Cd 2+. Therefore, among the tested ions, Pb 2+ was adsorbed most effectively by the succinylated starch, and Cu 2+ by the oxidized starch.

Original languageEnglish
Pages (from-to)171-177
Number of pages7
JournalCarbohydrate Polymers
Volume46
Issue number2
DOIs
Publication statusPublished - 2001 Oct 1

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Keywords

  • Langmuir constant
  • Metal-adsorption
  • Oxidized starch
  • Succinylated starch

ASJC Scopus subject areas

  • Food Science
  • Biochemistry

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