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Stability constants of mixed ligand complexes of some bivalent transition metal ions under laboratory and soils conditions

KrishiKosh

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Title Stability constants of mixed ligand complexes of some bivalent transition metal ions under laboratory and soils conditions
 
Creator Jain, Sweety
 
Contributor Nepal, J.K.
 
Subject Acidity, Wood, Ligands, Animal husbandry, Organic acids, Solutes, Inorganic acid salts, Concentrates, Extraction, Irrigation
 
Description The stability constants of binary and ternary complexes of Mn(II),
Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) with N-(2-hydroxyethyl) imino diacetic
acid, iminodiacetic acid, nitrilotriacetic acid, lactic acid, glycolic acid,
thioglycolic acid were determined potentiometrically at ionic strengths ( =
0.1 and 0.2 M KNO3) and temperature 298±0.5K. The protonation
constants of the ligands were determined using Calvin-Bijerrum pH.
titration technique as modified by Irving and Rossotti at ionic strengths (
= 0.1 and 0.2 M KNO3) and temperature (298±0.5 K). The following
computational techniques were used.
i) Interpolation of half values
ii) Pointwise calculation method
iii) Correction term method
The calculation of stability constants for binary (1:1) systems and ternary (1:1:1)
systems were carried out by Ramamoorthy and Santapa method. The stability constants for
binary systems Mn(II) / Fe(II) / Co(II) / Ni(II) / Cu(II) / Zn (II) – HIMDA / IMDA / NTA /
Lactic Acid / Glycolic acid / Thioglycolic acid were evaluated to characterize the stability
Introduction
of ternary complexes. The stability constants in these systems were found to follow the
general trend. Mn(II) < Fe(II) > Co(II) < Ni (II) < Cu (II) > Zn (II). Lactic acid complexes
were found to be more stable than other complexes with these metal ions.
The stability constants of ternary systems [M(II) – HIMDA / IMDA /
NTA – Lactic acid / Glycolic acid / Thioglycolic acid] in terms of metal ions
follow the general trend Mn(II) < Fe(II) > Co(II) < Ni(II) < Cu(II) > Zn(II). The
ternary complexes with lactic acid as secondary ligand are more stable as
compared to others. The stability constants in all systems generally
decrease with increase in ionic strength. The variation in stability due to
ligand – ligand interaction was interpreted by the expression.  log KM,
which quantities the stability of ternary complexes relative to binary
parent complex. In present investigation the variation in hetero-ligand
interaction follow the trend as given below :
At  = 0.1 M KNO3, temperature (298±0.5 K)
Mn(II) – IMDA-Lactic acid > HIMDA-Lactic acid > NTA – Lactic acid.
Fe(II) – IMDA-Lactic acid > HIMDA-Lactic acid > NTA – Lactic acid.
Co(II) – HIMDA -Lactic acid > IMDA -Lactic acid > NTA – Lactic acid.
Ni(II) – IMDA-Lactic acid > HIMDA-Lactic acid > NTA – Lactic acid.
Cu(II) – IMDA-Lactic acid > HIMDA-Lactic acid > NTA – Lactic acid.
Zn(II) – IMDA-Lactic acid > HIMDA-Lactic acid > NTA – Lactic acid.
Activity trend of complexes against C. falcatum and F. oxysporum :
In case of F. oxysporum the decreasing order of anti-fungal activity
of complexes of system at  = 0.1 M KNO3 (298±0.5K) is as follows :
Zn(II)-NTA-Thioglycolic acid > Zn(II)- NTA-Glycolic acid > Zn (II)-NTA >
Zn(II)
And in case of C. falcatum the decreasing order of antifungal activity
(MIC) is : Zn(II)-NTA-Glycolic acid > Zn(II)-NTA-Thioglycolic acid /
Zn(II)-NTA > Zn(II).
Effect of chalating agent on DTPA extractable metals :
Extractability of metals increases with the addition of NTA. But
when lactic acid was added with NTA extractability of Zn, Co, Cu
decreased while Ni, Mn increased but of Zn remained same.
 
Date 2016-12-23T11:20:20Z
2016-12-23T11:20:20Z
2005
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/92375
 
Language en
 
Format application/pdf
 
Publisher CCSHAU