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S. K. Saha ¹, R. N. Choudhury ¹, S. K. Chakravarti ¹

Affiliations
1 Department of Chemistry, University of North Bengal, Derjeeling, IN

Abstract

Multiple equilibria in humic acid-Cu(II) and humic acid-Ca systems in 0.1 N KNO₃, have been studied at different pH's using ion selective electrodes. At pH 4.8, Ca has been found to form only MA⁺, where as Cu(II) forms both MA⁺ and MA₂, complexes. Significant negative co-operative effect has been observed in all the systems studied, which is more prominent in Ca-humic acid complex at low pH. Logarithms of intrinsic stability constant, K₀, ranged from 7.5 to 8.5 for Cu(II) and 5.8 to 6.0 for Ca-complexes. Results are compared with those for the two synthetic model humic acid-metal systems.

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Himangshu S. Bose ¹, S. K. Chakravarti ¹

Affiliations
1 Department of Chemistry, North Bengal University, Darjeeling-734430, IN

Abstract

Tha solubilizations of a series of thiazine dyes have been studied with three anionic surfactants having different hydrocarbon chain. The quality of the solubilized dye is found to decrease with the increase of chain length of the surfactants and their order in respect of solubilization is sodium dodecyl sulfate (NaDS) > sodium heptadecyl sulfate (NaHS) > Dodecyl benzene sodium sulfonate (DBSS). In aqueous medium the nature of the dyes, their structure and size are important parameters to influence the behaviour of the solubilizers.

Keywords

Limit of Solubilization, Thiazine Dyes, Micelles.

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H. S. Bose ¹, S. K. Chakravarti ¹

Affiliations
1 Department of Chemistry, North Bengal University, Darjeeling-734430, IN

Abstract

The effect of alkali metal chlorides on the metachromatic behaviour of Trimethyl propyl thionine (TMPT) and Diethyl methyl propyl thionine (DEMPT) as induced by polyacrylic acid (PAA) was investigated spectrophotometrically. The size of hydrated ion and hydrophobicity of substituents were not found to be significant factors to influence the above behaviour. The alkali metal cation affinity sequence was observed as Li⁺ > K⁺ > Cs⁺ for polyacrylic acid exchangers. A large amount of destruction of metachromasy was observed in PAA-TMPT and PAA-DEMPT on addition of small amounts of cetyl trimethyl ammonium chloride (CTACI) and Decyl trimethyl ammonium chloride (DTACI) and their order CTACI > DTACI.

Keywords

Polyacrylic Acid Metachromasy, Micelles, Thiazine Dyes, TMPT & DEMPT, Hydrophobicity.

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U. K. Pal ¹, S. K. Chakravarti ¹

Affiliations
1 Department of Chemistry, University of North Bengal, Dist. Darjeeling, West Bengal, 734 430, IN

Abstract

The study of the exchange pattern on soil and peat fulvic acids (SFA and PFA) reveals that the uptake of Coen₃³⁺ increases with increase in pH but, after reaching a maximum at pH 6.5 it starts decreasing, and finally attains a steady value. The release isotherms indicate the following order of reactivity: Li ≈ Na < K < Rb < Cs < H for monovalent cations, (the reversal of exchangeability for Li and Na taking place at lower concentration) and Mg < Ca < Sr < Ba for the divalent cations. However, for organic cations the order of exchangeability is (C₂H₅)₄N > (CH₃)₄N at lower concentration but the reverse is observed at higher concentration. The release isotherms with monovalent cations distinctly display that the exchange processes occur in three stages. Kielland's equation has been harnessed to find out the thermodynamic equilibrium constants and Gibbs free energy change for exchange reactions involving bivalent cations. It is found that Log of corrected selectivity coefficients or thermodynamic equilibrium constants, when plotted separately against hydrated ionic radii and the reciprocal of Debye-Huckel parameter a⁰, the relative affinities of the counter ions for the exchange substrates are much better correlated with a⁰ rather than with hydrated ionic radii.

Keywords

Fulvic Acid, Coen₃, Uptake, Exchangeability, Selectivity Coefficients, Thermodynamic Equilibrium Constant.

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S. K. Chakravarti ¹

Affiliations
1 SK Chakravarti, Professor, Physics, National Institute of Technology

Abstract

Lexis Conferences is pleased to welcome everyone to attend our forthcoming Nanotech Forum 2020 which is going to be held during March 27-28, 2020 in Madrid, Spain. The meet will focus on the theme “Nanotechnology – The key to Future”.

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