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Chelation of Vanadium( IV ) by a Natural and Edible Biopolymer Poly( γ ‐glutamic acid) in Aqueous Solution: Structure and Binding Constant of Complex
Author(s) -
Karmaker Subarna,
Saha Tapan K.
Publication year - 2008
Publication title -
macromolecular bioscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.924
H-Index - 105
eISSN - 1616-5195
pISSN - 1616-5187
DOI - 10.1002/mabi.200700121
Subject(s) - biopolymer , chelation , aqueous solution , chemistry , vanadium , polymer chemistry , glutamic acid , nuclear chemistry , inorganic chemistry , chemical engineering , polymer , organic chemistry , amino acid , biochemistry , engineering
The naturally occurring edible biopolymer poly( γ ‐glutamic acid) ( γ ‐PGA) is shown to be an efficient chelating agent of vanadium( IV ). The structure of poly( γ ‐glutamic acid)oxovanadium( IV ) (VO‐ γ ‐PGA) complex in solution has been analyzed by electron spin resonance and UV‐visible absorption spectra. The equatorial coordination sphere of vanadium( IV ) is proposed to be [2 × carboxylate (2O)–VO–(OH 2 ) 2 ]. The binding isotherm is determined for suspensions of γ ‐PGA in vanadium( IV ) oxide sulfate (VS) solutions of different concentrations, and the data have been adjusted to fit the modified Langmuir equation. The maximum amount of vanadium bound per gram of γ ‐PGA is estimated to be 141 mmol · g −1 with a binding constant of 22 L · g −1 at pH 3.