Chemical Speciation of Binary Complexes of Pb(Ii), Cd(Ii) and Hg(Ii) with L-Methionine in Propylene Glycol -Water Mixture

G. Nageswara Rao; N. Vijaya Kumar; T. Siva Rao; K. Bhaskara Rao; N.V. V. Simhadri

G. Nageswara Rao School of Chemistry, Andhra University, Visakhapatnam-530003, India.
N. Vijaya Kumar DNR College, Bhimavaram-534202, W. G. Dt., AP. INDIA
T. Siva Rao School of Chemistry, Andhra University, Visakhapatnam-530003, India.
K. Bhaskara Rao DNR College, Bhimavaram-534202, W. G. Dt., AP. INDIA
N.V. V. Simhadri DNR College, Bhimavaram-534202, W. G. Dt., AP. INDIA

Keywords: Complex equilibria, Chemical speciation, L-Methionine, Propyleneglycol, Metals.

Abstract

Chemical speciation of Pb(II), Cd(II) and Hg(II) complexes of L-methionine in 0.0-60.0 % v/v propylene glycol-water mixtures has been studied pH metrically maintaining an ionic strength of 0.16 M at 303 K. The active forms of ligand are LH₃⁺, LH₂ and LH. The predominant species detected are MLH, ML and ML₂. Models containing different numbers of species were refined by using the computer program MINIQUAD75. The best-fit chemical models were arrived at based on statistical parameters. The trend in variation of complex stability constants with change in the dielectric constant of the medium is explained on the basis of electrostatic and non-electrostatic forces.

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Author Biographies

G. Nageswara Rao, School of Chemistry, Andhra University, Visakhapatnam-530003, India.

Professor

N. Vijaya Kumar, DNR College, Bhimavaram-534202, W. G. Dt., AP. INDIA

Lecturer in Chemistry

T. Siva Rao, School of Chemistry, Andhra University, Visakhapatnam-530003, India.

Professor

K. Bhaskara Rao, DNR College, Bhimavaram-534202, W. G. Dt., AP. INDIA

Lecturer in Chemistry

N.V. V. Simhadri, DNR College, Bhimavaram-534202, W. G. Dt., AP. INDIA

Lecturer in Chemistry

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