scholarly journals Protonation Equilibria of L-Aspartic, Citric and Succinic Acids in Anionic Micellar Media

2009 ◽  
Vol 6 (2) ◽  
pp. 561-568 ◽  
Author(s):  
P. Srinivasa Rao ◽  
B. Srikanth ◽  
V. Samba Siva Rao ◽  
C. Kamala Sastry ◽  
G. Nageswara Rao
Keyword(s):  
Citric Acid ◽  
Ionic Strength ◽  
Computer Program ◽  
Succinic Acid ◽  
Protonation Constants ◽  
Micellar Media ◽  
Statistical Parameters ◽  
Protonation Equilibria ◽  
The Impact ◽  
Best Fit

The impact of sodium lauryl sulphate (SLS) on the protonation equilibria ofL-aspartic acid, citric acid and succinic acid has been studied in various concentrations (0.5-2.5%w/v) of SLS solution maintaining an ionic strength of 0.16 mol dm-3at 303 K. The protonation constants have been calculated with the computer program MINIQUAD75 and the best fit models have been calculated based on statistical parameters. The trend of log values of step-wise protonation constants with mole fraction of the medium has been explained based on electrostatic and non-electrostatic forces operating on the protonation equilibria. The effects of errors on the protonation constants have also been presented.

Effect of Solvent on Protonation Equilibria of L-Serine and L-Tryptophan in Ethylene Glycol-Water Mixtures

2021 ◽  
Vol 25 (7) ◽  
pp. 124-129
Author(s):  
Ch. Sudhakar ◽  
Allabakshu Shaik ◽  
M. Ramanaiah ◽  
Ch. Nageswara Rao
Keyword(s):  
Dielectric Constant ◽  
Ethylene Glycol ◽  
Protonation Constants ◽  
Statistical Parameters ◽  
Protonation Equilibria ◽  
Effect Of Solvent ◽  
R Factor ◽  
Chemical Models ◽  
Best Fit ◽  
Skewness And Kurtosis

Protonation equilibria of L-serine and L-tryptophan in varying compositions (0.0-50.0 % v/v) of ethylene glycol-water mixtures were investigated pH-metrically. Titrations were performed at 303.0 K and the ionic strength of the medium was maintained at 0.16 mol L-1 using sodium chloride. The protonation constants have been calculated with the computer program MINIQUAD 75 and are selected based on statistical parameters. The best fit chemical models of the protonation equilibria were based on crystallographic R-factor, χ2, skewness and kurtosis. The protonation constants of L-serine and L-tryptophan change linearly with increasing ethylene glycol content. This is attributed to the dielectric constant of the medium.

scholarly journals Effect of Solvent on Protonation Equilibria ofL-Proline andL-Valine in 1, 2-Propanediol-Water Mixtures

2012 ◽  
Vol 9 (2) ◽  
pp. 517-524 ◽  
Author(s):  
P. Bhushanavathi ◽  
B. Veeraswamy ◽  
G. Nageswara Rao ◽  
U. Viplavaprasad
Keyword(s):  
Dielectric Constant ◽  
Sodium Chloride ◽  
Ionic Strength ◽  
Protonation Constants ◽  
Protonation Equilibria ◽  
Effect Of Solvent ◽  
R Factor ◽  
Chemical Models ◽  
Best Fit ◽  
Skewness And Kurtosis

Protonation equilibria ofL-proline and L-valine in varying compositions (0.0-60.0% v/v) of 1, 2-Propanediol-water mixtures were investigated pH-metrically. Titrations were performed at 303.0 K and the ionic strength of the medium was maintained at 0.16 mol L-1using sodium chloride. The best fit chemical models of the protonation equilibria were based on crystallographic R-factor, Χ2, skewness, and kurtosis. All the protonation constants of proline and valine increased with increasing propanediol content. This is attributed to the dielectric constant of the medium.

scholarly journals Speciation Studies of L-Histidine Complexes of Pb(II), Cd(II), and Hg(II) in DMSO-Water Mixtures

2012 ◽  
Vol 2012 ◽  
pp. 1-9
Author(s):  
K. Bharath Kumar Naik ◽  
B. Ananda Kumar ◽  
S. Raju ◽  
G. Nageswara Rao
Keyword(s):  
Dielectric Constant ◽  
Ionic Strength ◽  
Complex Formation ◽  
Species Distribution ◽  
Statistical Parameters ◽  
Experimental Conditions ◽  
Equilibrium Study ◽  
Predominant Species ◽  
Chemical Models ◽  
Best Fit

Equilibrium study on complex formation of L-histidine with Pb(II), Cd(II), and Hg(II) has been investigated pH metrically in DMSO-water mixtures (0–60% v/v) at 303 K and 0.16 mol L−1 ionic strength. The predominant species detected for Pb(II) and Cd(II) are ML2H4, ML2H3, ML2H2, ML2H, and ML2 and those for Hg(II) are ML2H4, ML2H3, ML2, and ML. The appropriateness of experimental conditions is verified by introducing errors intentionally in the concentrations of ingredients. The 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 stability constants of the complexes with dielectric constant of the medium is attributed to the electrostatic and nonelectrostatic forces. The species distribution and the plausible equilibria for the formation of the species are also presented.

scholarly journals Determination of Protonation Constants of Viral Inhibitor, Aurintricarboxylic Acid in SDS and CTAB Micellar Media: A Potentiometric Study

2021 ◽  
Vol 33 (10) ◽  
pp. 2301-2305
Author(s):  
K. Bhargavi ◽  
P. Shyamala ◽  
G. Nageswara Rao
Keyword(s):  
Formation Constants ◽  
Protonation Constants ◽  
Micellar Media ◽  
Statistical Parameters ◽  
Chi Square ◽  
Aurintricarboxylic Acid ◽  
Viral Inhibitor ◽  
Chi Square Test ◽  
Anionic Micelle

Protonation constants of a viral inhibitor, aurintricarboxylic acid were determined using potentiometric method of data acquisition followed by chemometric modelling methods of analysis in the presence of two different kinds of micellar media, CTAB, a cationic micelle and SDS, an anionic micelle. MINIQUAD75 program was used for the determination of the plausible species and their corresponding formation constants at 303 ± 0.1 K and 0.01 M ionic strength. Five formation constants were identified corresponding to five ionizable hydrogens. Species concentration distribution diagrams were generated using Origin software. Best-fit chemical models were selected on the basis of statistical parameters like standard deviation (SD), U (sum of the squares of the residuals in mass balance equations) and chi-square test. It was found that the formation constants are lower in CTAB micellar medium while there is no significant change in the presence of SDS compared to aqueous medium.

scholarly journals Effect of micelles on the chemical speciation of binary complexes of Co(II), Nii(II), Cu(II) and Zn(II) with succinic acid

2009 ◽  
Vol 74 (7) ◽  
pp. 745-754
Author(s):  
Bathula Srikanth ◽  
Srinivasa Rao ◽  
Siva Rao ◽  
Kamala Sastry ◽  
Nageswara Rao
Keyword(s):  
Ionic Strength ◽  
Computer Program ◽  
Succinic Acid ◽  
Mole Fraction ◽  
Chemical Speciation ◽  
Ionic Surfactants ◽  
Binary Complex ◽  
Complex Species ◽  
Binary Complexes ◽  
Modelling Studies

Speciation of Co(II), Ni(II), Cu(II) and Zn(II) complexes with succinic acid in the presence of anionic, cationic and non-ionic surfactants at an ionic strength of 0.16 mol dm-3 and temperature 303 K were investigated pH metrically. The existence of different binary complex species was established from modelling studies using the computer program MINIQUAD75. The decreased stability of the complexes with increasing micellar content was explained by electrostatic forces. The influence of the micelles on the chemical speciation is discussed based on the mole fraction of the medium. Distribution diagrams of various species of the complexes in relation to pH are presented.

scholarly journals Mixed ligand complexes of essential metal ions with L-glutamine and succinic acid in SLS-water mixtures

2012 ◽  
Vol 77 (4) ◽  
pp. 453-463 ◽  
Author(s):  
Hima Bindu ◽  
Nageswara Rao
Keyword(s):  
Succinic Acid ◽  
Electrostatic Interactions ◽  
Ternary Complexes ◽  
Mixed Ligand ◽  
Mixed Ligand Complexes ◽  
Statistical Parameters ◽  
Chemical Models ◽  
Chelate Effect ◽  
Binary Complexes ◽  
Best Fit

Speciation of mixed ligand complexes of Co(II), Ni(II) and Cu(II) with L-glutamine and succinic acid was studied in varying amounts (0.0-2.5% w/v) of sodium lauryl sulphate in aqueous solutions maintaining an ionic strength of 0.16 mol L-1 (NaCl) at 303.0 K. Titrations were carried out in the presence of different relative concentrations (M : L : X = 1 : 2 : 2, 1 : 4 : 2, 1 : 2 : 4) of metal (M) to L-glutamine (L) to succinic acid (X) with sodium hydroxide. Stability constants of ternary complexes were refined with MINIQUAD75. The best-fit chemical models were selected based on statistical parameters and residual analysis. The species detected were ML2X, MLX, MLXH and MLXH2 for Co(II), Ni(II) and Cu(II). Extra stability of ternary complexes compared to their binary complexes was believed to be due to electrostatic interactions of the side chains of ligands, charge neutralization, chelate effect, stacking interactions and hydrogen bonding. The species distribution with pH at different compositions of SLS and plausible equilibria for the formation of species were also presented.

scholarly journals Mononuclear Binary Complex Formation Equilibria of L-Ornithine with Biologically Essential Metals in TBAB Micellar Media

2019 ◽  
Vol 31 (6) ◽  
pp. 1383-1388
Author(s):  
A.G. ATNAFU ◽  
R. SRINIVASU ◽  
P. SHYAMALA ◽  
G. NAGESWARA RAO
Keyword(s):  
Ionic Strength ◽  
Tetrabutylammonium Bromide ◽  
Binary Complex ◽  
Statistical Parameters ◽  
Complex Formation Equilibria ◽  
Surfactant Micelle ◽  
Ph Values ◽  
Chemical Models ◽  
Formation Equilibria ◽  
Best Fit

Investigation of mononuclear complex of L-ornithine in tetrabutylammonium bromide (TBAB, a cationinc surfactant) micelle media has been made pH metrically at constant temperature and ionic strength in different percentage of micellar solutions (0.0-2.5 %). Stability constants and best fit model for metal complexes were obtained by MINIQUAD75 computer program on the basis of the analysis of residues and other statistical parameters. Accordingly, ML, ML2, MLH and ML2H for both Co(II) and Cu(II) and ML2 and ML2H for Ni(II) mononuclear chemical models were obtained. The stabilization/destabilization equilibria of the binary system for the model species with percentage composition of micelles at constant ionic strength and temperature could be attributed to dielectric constant and other intrinsic interaction properties of tetrabutylammonium bromide micelle with ligands and metal ions. The plot of percentage of species against pH values has been generated from SIM refined data using origin85 software.

scholarly journals Ingredient-Dependent Extent of Lipid Oxidation in Margarine

Antioxidants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 105
Author(s):  
Sarah Fruehwirth ◽  
Sandra Egger ◽  
Dennis Kurzbach ◽  
Jakob Windisch ◽  
Franz Jirsa ◽  
...  
Keyword(s):  
Citric Acid ◽  
Lipid Oxidation ◽  
Oxidative Stability ◽  
Green Tea ◽  
Acyl Chain ◽  
Green Tea Extract ◽  
Tocopheryl Acetate ◽  
Tea Extract ◽  
The Impact ◽  
Β Carotene

This study reports the impact of margarine-representative ingredients on its oxidative stability and green tea extract as a promising antioxidant in margarine. Oil-in-water emulsions received much attention regarding factors that influence their oxidative stability, however, water-in-oil emulsions have only been scarcely investigated. Margarine, a widely consumed water-in-oil emulsion, consists of 80–90% fat and is thermally treated when used for baking. As different types of margarine contain varying additives, their impact on the oxidative stability of margarine during processing is of pressing importance. Thus, the influence of different ingredients, such as emulsifiers, antioxidants, citric acid, β-carotene and NaCl on the oxidative stability of margarine, heated at 80 °C for 1 h to accelerate lipid oxidation, was analyzed by the peroxide value and oxidation induction time. We found that monoglycerides influenced lipid oxidation depending on their fatty acyl chain. α-Tocopheryl acetate promoted lipid oxidation, while rosemary and green tea extract led to the opposite. Whereas green tea extract alone showed the most prominent antioxidant effect, combinations of green tea extract with citric acid, β-carotene or NaCl increased lipid oxidation in margarine. Complementary, NMR data suggested that polyphenols in green tea extracts might decrease lipid mobility at the surface of the water droplets, which might lead to chelating of transition metals at the interface and decreasing lipid oxidation.

Enrichment of hydrogen production from fruit waste biomass using ozonation assisted with citric acid

2021 ◽  
pp. 0734242X2110103
Author(s):  
Anbazhagan Sethupathy ◽  
Pushkar Kumar Pathak ◽  
Palani Sivashanmugam ◽  
Chelliah Arun ◽  
Jayakumar Rajesh banu ◽  
...  
Keyword(s):  
Citric Acid ◽  
Hydrogen Production ◽  
Suspended Solid ◽  
Net Energy ◽  
Waste Biomass ◽  
Acid Pretreatment ◽  
Disintegration Time ◽  
Fruit Waste ◽  
The Impact ◽  
Acid Dosage

In this study, the impact of ozonation abetted with the citric acid pretreatment (OZCAP) method on fruit waste was investigated for ameliorating hydrogen production. Initially, the ozonation pretreatment (OZP) method was performed by varying ozone (O3) dosage and disintegration time. At optimized conditions (O3 dosage (0.04 g/g suspended solid; SS) and disintegration time (40 minutes)), 17.6% of liquefied organics emancipate rate (LER) and 13.5% of SS reduction were perceived. Further augmenting LER of fruit waste, OZCAP method was proceeded by varying citric acid dosage and disintegration time at an optimized OZP dosage (0.04 g/g SS). A higher LER (24.4%) and SS reduction (19%) were described at an optimal citric acid dosage (0.03 g/g SS) and disintegration time (20 minutes). Then, the hydrogen production potential of OZCAP, OZP and raw fruit waste were evaluated in which OZCAP method exhibited a higher cumulative hydrogen production (30 mL/g volatile solids). Energy valuation reveals that OZCAP method exhibited a net energy of 3.7 kWh/kg of fruit waste.

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