The phase separation, interaction forces and thermodynamics of sodium alginate and TX-100 mixture in the manifestation of alcohols: UV-visible and cloud point measurement studies

Physicochemical parameters and modes of interaction associated with the micelle formation of a mixture of tetradecyltrimethylammonium bromide and cefixime trihydrate: effects of hydrotropes and temperature

The interaction between an antibiotic drug (cefixime trihydrate (CMT)) and a cationic surfactant (tetradecyltrimethylammonium bromide (TTAB)) was examined in the presence of both ionic and non-ionic hydrotropes (HTs) over the temperature range of 300.55 to 320.55 K. The values of the critical micelle concentration (CMC) of the TTAB + CMT mixture were experienced to have dwindled with an enhancement of the concentrations of resorcinol (ReSC), sodium benzoate (NaBz), sodium salicylate (NaS), while for the same system, a monotonically augmentation of CMC was observed in aq. 4-aminobenzoic acid (PABA) solution. A gradual increase in CMC, as a function of temperature, was also observed. The values of the degree of counterion binding (β) for the TTAB + CMT mixture were experienced to be influenced by the concentrations of ReSC/NaBz/NaS/PABA and a change in temperature. The micellization process of TTAB + CMT was observed to be spontaneous (negative standard Gibbs free energy change (ΔG0m)) at all conditions studied. Also, the values of standard enthalpy change (ΔH0m) and entropy change (ΔS0m) were found negative and positive, respectively (with a few exceptions), for the test cases indicating an exothermic and enthalpy-entropy directed micellization process. The recommended interaction forces between the components in the micellar system are electrostatic and hydrophobic interactions. In this study, the values of ΔC0m were negative in aqueous NaBz, ReSC, and PABA media, and positive in case of NaS. An excellent compensation scenario between the enthalpy and entropy for the CMT + TTAB mixed system in the investigated HTs solutions is well defined in the current work.

Investigation of the impacts of simple electrolytes and hydrotrope on the interaction of ceftriaxone sodium with cetylpyridinium chloride at numerous study temperatures

Herein, interactions between cetylpyridinium chloride (CPC) and ceftriaxone sodium (CTS) were investigated applying conductivity technique. Impacts of the nature of additives (e.g. electrolytes or hydrotrope (HDT)), change of temperatures (from 298.15 to 323.15 K), and concentration variation of CTS/additives were assessed on the micellization of CPC + CTS mixture. The conductometric analysis of critical micelle concentration (CMC) with respect to the concentration reveals that the CMC values were increased with the increase in CTS concentration. In terms of using different mediums, CMC did not differ much with the increase in electrolyte salt (NaCl, Na2SO4) concentration, but increased significantly with the rise of HDT (NaBenz) amount. In the presence of electrolyte, CMC showed a gentle increment with temperature, while the HDT showed the opposite trend. Obtained result was further correlated with conventional thermodynamic relationship, where standard Gibb's free energy change ( Δ G m o ) , change of enthalpy ( Δ H m o ) , and change of entropy ( Δ S m o ) were utilized to investigate. The Δ G m o values were negative for all the mixed systems studied indicating that the micellization process was spontaneous. Finally, the stability of micellization was studied by estimating the intrinsic enthalpy gain (Δ H m o , ∗ ) and compensation temperature (Tc). Here, CPC + CTS mixed system showed more stability in Na2SO4 medium than the NaCl, while in NaBenz exhibited the lowest stability.

Influence of twin-headed gemini micellar system on the study of methionine amino acid with ninhydrin in buffer solution

The influence of double-headed gemini was examined in the present study by studying the amino acid methionine mixed with ninhydrin in CH₃COOH-CH₃COONa buffer solvent. The absorbance was monitored at fixed time intervals with UV-vis spectroscopy. An impact typical of surfactants was observed on the ninhydrin-methionine reaction and explained by a pseudo-phase model of micelles. The effect of different temperatures (343 to 363 K) was also determined. Based on data showing the impact of temperature on k_ψ , several relevant thermodynamic quantities, ΔH ^#, ΔS ^#, and E _a, were calculated using linear least-squares regression. In addition, the influence of the other reaction ingredients on the reaction, that is, pH and the concentration of ninhydrin and methionine, was studied. The CMC (critical micelle concentration) of pure geminis and the surfactant system with methionine and ninhydrin was evaluated at two temperatures, i.e. at 303 K and 353 K by conductivity measurements. The CMC values of pure gemini surfactants evaluated in the existing case at 303 K are concordant with the results stated before. Moreover, other parameters, including rates and binding constants, were calculated.

Interactional, Functional and Biological Properties of Lactone Sophorolipid (LSL) and Collagen Oligopeptides (COP) in Aqueous Solution

For the mixed aqueous solution of LSL and COP, the interaction mode and mechanism have been comprehensively studied using multispectral methods including fluorescence spectrum, ultraviolet-visible adsorption spectrum (UV-Vis), and circular dichroism spectrum (CD). Then its surface activity, particle size, foaming, emulsifying, viscosity, and antibacterial properties are evaluated in detail by surface tension measurement (ST), dynamic light scattering (DLS), oscillametric method, spectrophotometer, ubbelohde viscometer and zone of inhibition separately. Compared with the single LSL or COP aqueous solution, the mixed system shows different performance optimizations in different aspects. The surface activity and foaming properties are mainly attributed to LSL, and the viscosity is attributed to COP. Fluorescence spectroscopy results show that the fluorescence distribution of COP has significant changes by the LSL addition and a static quenching mechanism is proved. The results of UV-Vis and CD spectra also show the changing conformation of COP by the LSL addition. The data of thermodynamic parameters prove that the combination of LSL and COP is a spontaneous exothermic process and is an enthalpy-driven process. The interaction mechanism between LSL and COP is very helpful for the application and development of the mixed mild biosurfactant-protein system used in the cosmetic and food industries.