Phase Separation and Thermodynamic Behavior of Triton X-100 in the Occurrence of Levofloxacin Hemihydrates: Influence of Additives

J of Physical Organic Chem

2019

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Kinetic and mechanistic investigations of [Zn (II)‐Trp]+ and ninhydrin in aqueous and cationic cetyltrimethylammonium bromide (CTAB) surfactant have been executed in CH3COOH‐CH3COONa buffers of pH 5.0. Spectrophotometric as well as conductometric techniques were employed to carry out the study at experimental temperature. The values of rate constant (kobs in aqueous and kψ in CTAB surfactant) and binding parameters (KB for [Zn (II)‐Trp]+ and KN for ninhydrin) have been determined by the means of a computer program referred to as linear least squares technique. Fractional‐ and first‐order kinetics were found in ninhydrin and [Zn (II)‐Trp]+, respectively, in aqueous and cationic CTAB. Study was catalyzed and accelerated by CTAB surfactant. An increase in CTAB surfactant concentration from 0 to 45 mmol kg−1 resulted to an increase in kψ from 2.5 × 10−5 s−1 to 22.7 × 10−5 s−1. Surfactant concentration beyond 45 mmol kg−1 had a slow decreasing effect in kψ. In order to elucidate CTAB effect on kψ, a pseudo‐phase model of micelles was applied.

Section: Introductionmentioning

confidence: 99%

Kinetic and mechanistic investigations of [Zn (II)‐Trp]⁺ and ninhydrin in aqueous and cationic CTAB surfactant

Kumar

J of Physical Organic Chem

2019

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“…Graph of ln X s against T were observed nonlinear as well as a representative graph is exposed in Figure . Tangents were drawn via the necessary points of the graph and the slope of the tangent is considered as ∂ lnX s /∂ T is utilized to compute ∆H c 0 . The physico‐chemical indicators for the (TX 100+ diols) mixture in aqueous medium are shown in Table and Tables S2 and S3.…”

Section: Resultsmentioning

confidence: 99%

Impact of different diols/polyols on the phase separation behavior as well as thermodynamic properties of tween 80

Mishu

Amin

J of Physical Organic Chem

et al. 2019

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Herein, the cloud points (CPs) of tween 80 (Tw 80) in water/(water + diols [ethanediol, propanediol, and butanediol])/(water + polyols [glucose, fructose, and sorbitol]) systems were measured. For diols‐Tw 80‐water system and polyols‐Tw 80‐water system, the CP values were obtained to reduce gradually with increasing content of diols and polyols at a particular concentration of Tw 80. For a certain concentration of Tw 80 having different contents of diols, the observed ∆H0c, as well as ∆S0c values, were negative over the range of concentration of diols studied, and the negative values of ∆H0c and ∆S0c were reduced with the enhancement of the content of diols. The values of ∆H0c were negative, which indicate the process was exothermic. The clouding process of Tw 80 in the presence of different diols is mainly enthalpy‐controlled process, while the contributions of enthalpy tend to reduce with enhancing of the contribution of diols. In the case of polyols‐Tw 80 mixture in an aqueous environment, the ∆Gc0 values were achieved positive. The values of ∆Hc0 and ∆Sco were obtained negative for studied systems, while the negative values reduce with enhancing of polyol (glucose and fructose) concentrations. For sorbitol‐Tw 80 system, the values of ∆Hc0 were observed to be negative and the negative magnitudes reduce with enhancing of sorbitol concentrations. The thermodynamic parameters of transfer are also evaluated and illustrated in detail.

“…Surfactants contain a polar head (hydrophilic group) and a non-polar (hydrophobic hydrocarbon tail). They have been employed in several aspects of chemical, biological and industrial processes [1][2][3][4][5]. Surfactants aggregate frequently and catalyse the chemical reactions, but they also inhibit reactions.…”

Section: Introductionmentioning

confidence: 99%

Catalytic influence of 16- s -16 gemini surfactants on the rate constant of histidine and ninhydrin

Kumar

2020

R. Soc. open sci.

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The present paper reports the catalytic influence of 16-s-16 (spacer (s) = 4, 5, 6) gemini surfactants on the rate constant of histidine and ninhydrin at 343 K and pH 5.0 using the spectrophotometric technique. The effect of varying amounts of geminis was made on the rate constant of histidine and ninhydrin keeping other constituents constant. Characteristics of the rate constant (k ψ ) versus [gemini] depict the effect of surfactants on the rate constant. A systematic explanation about the effect of surfactants is revealed and discussed in the text. The influence of different parameters that includes [reactants], temperature and pH has also been performed on the study. In order to determine the critical micelle concentration (cmc) of pure surfactants and their solution mixtures, conductivity measurement was employed. By using the Eyring equation, activation parameters at different temperatures have been obtained. The resultant data of k ψ versus [gemini] plot were rationalized with the pseudo-phase model of micelles.