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This study explores the mixed micellization between anionic surfactant sodium dodecyl sulfate (SDS) and cationic surfactant cetyltrimethylammonium bromide (CTAB) in H 2 O/H 2 O + alcohol mixed medium over a temperature range of 298.15− 318.15 K using the conductivity measurement technique. The experimentally estimated critical micelle concentration (cmc) values are lower than respective ideal cmc (cmc id ), which reveals the presence of the interaction among the surfactants. The cmc values disclose that the presence of lower carbon alcohol (methanol and ethanol) favors the mixed micellization of SDS and CTAB. In the presence of alcohol, the extent of micelle ionization (g) of the system enhances. Different theoretical models (Rubingh/ Motomura/Rodenas) were applied to estimate micellar mole fraction (X 1 ), and the obtained results illustrate the significant participation of CTAB in the mixed micellization. The magnitudes of activity coefficients (f 1 and f 2 < 1) as well as interaction parameter (β < 0) in almost every case clarify the attractive relations between CTAB and SDS. The standard free energy of mixed micellization (ΔG m °) and excess free energy of micellization (ΔG ex ) illustrate the spontaneous mixed micelle formation and greater stability of the SDS + CTAB micelle than that of individual surfactants, respectively. The ΔH m °as well as ΔS m °values of SDS + CTAB micellization were also estimated and illustrated in detail. The values of ΔG m,tr °for SDS + CTAB illustrate that micellization is more spontaneous in the presence of ethanol than in the presence of methanol. The values of ΔH m,tr °and ΔS m,tr °were also calculated and discussed.

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Hydrogenase biomimetics: structural and spectroscopic studies on diphosphine-substituted derivatives of Fe2(CO)6(µ-edt) (edt = ethanedithiolate) and Fe2(CO)6(µ-tdt) (tdt = 1,3-toluenedithiolate).

A conductometric study of the mixed micellization behavior between cetyltrimethylammonium bromide (CTAB, a cationic surfactant) and sodium dodecyl sulfate (SDS, an anionic surfactant) was carried out in the absence/presence of various percentages of chitosan in the temperature range of 298.15–318.15 K. The deviations of critical micelle concentration (cmc) from the ideal values indicate the interaction between CTAB and SDS. The micellar mole fraction values according to different proposed models X1Rub (Rubingh), X1M (Motomura), X1Rod (Rodenas), and X1id (ideal mole fraction) were estimated and the results obtained reveal the high contribution of CTAB in the mixed micellization, which enhances with the increase of the mole fraction of CTAB. The negative magnitudes of normalΔGm0 indicate the spontaneous formation of mixed micelles between CTAB and SDS. The values of activity coefficients (f1 and f2) were less than unity and the values of the interaction parameter (β) are negative in all cases, which indicate the attractive interaction between CTAB and SDS. The negative values of excess free energy of micellization (ΔGex) signify the stability of the mixed micelles. The negative values of normalΔHm0 in the chitosan systems indicate that micellization is exothermic. The values of normalΔSm0 were found to be positive in all cases.

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