The sponge of Luffa cylindrical (LFC), a fibrous material, was employed as adsorbent for the removal of Brilliant Green (BGD) from aqueous effluent via batch studies. The optimum removal of BGD was found at pH 8.2 and the equilibrium was attained within 3 hours. The kinetic data are analyzed using several models including pseudo-first-order, pseudo-second-order, power function, simple elovich, intraparticle diffusion, and liquid film diffusion. The fitting of the different kinetics models to the experimental data, tested by error analysis, using the linear correlation coefficient ( 2 ) and chi-square analysis ( 2 ), showed that the mechanism of adsorption process was better described by pseudo-second-order and power function kinetic models. The equilibrium isotherm data were analyzed using Langmuir, Freundlich, and Temkin models and the sorption process was described by the Langmuir isotherm with maximum monolayer adsorption capacity of 18.2 mg/g at 303 K. The thermodynamic properties Δ 0 , Δ 0 , and Δ 0 showed that adsorption of BGD onto LFC was spontaneous, endothermic, and feasible within the temperature range of 303-313 K.

Mixed-micelle formation in the binary mixtures of dodecyltrimethylammonium bromide (DTABr) and cetyltrimethylammonium bromide (CTABr) surfactants in water-ethanolamine mixed solvent systems has been studied by conductometric method in the temperature range of 298.1 to 313.1 K at 5 K intervals. It was observed that the presence of ethanolamine forced the formation of mixed micelle to lower total surfactant concentration than in water only. The synergistic interaction was quantitatively investigated using the theoretical models of Clint and Rubingh. The interaction parameter β12 was negative at all the mole fractions of DTABr in the surfactant mixtures indicating a strong synergistic interaction, with the presence of ethanolamine in the solvent system resulting in a more enhanced synergism in micelle formation than in water only. The free energy of micellization ΔGM values was more negative in water-ethanolamine mixed solvent system than in pure water indicating more spontaneity in mixed micelle formation in the presence of ethanolamine than in pure water.

Simple and differential UV/Visible spectroscopic method were used to monitored the interaction of Sodium dodecyl sulphate (SDS) and Sodium-N-laouryl sarcosinate (SLS) with crystal violet (CV) in pre-micellar and post-micellar concentration range. The results showed that the peak of CV at 590nm was unperturbed in CV/SDS system, but the intensity increased as surfactant concentration increased, unlike in the CV/SLS system. This is an indication that strong interaction between occurred CV and surfactants molecule. Absorption data were also used to obtain partition coefficient (Kc) values and binding constant (Kαβ) values from which the free energy of partition (0 c G ) and the free energy of binding (0 G  ) were estimated. From the partition coefficient (Kc) values, it could be inferred that the solubilization of CV is more pronounced and spontaneous in the SDS than in the SLS micellar media.

The effect of triethanolamine, a solvent with wide technical and industrial benefit on the micellization of an aqueous mixture of cationic surfactants, dodecyltrimethylammonium bromide (DETAB) and hexadecyltrimethylammonium bromide (HATAB) was studied to examining the stability of the mixed micelles at 298.1, 303.1, 308.1 and 313.1 K using the electrical conductance method. The values of the critical micelle concentration (C*) were found to decrease with an increase in the concentration of triethanolamine (TEA). The values of the free energy of micellization (ΔGm) were negative at a particular temperature, and the extent of spontaneity was discovered to increase when the concentration of TEA was increased. However, an increase in temperature was observed to have a negative linear relationship with the spontaneity of the process. The formation of the mixed micelles was an exothermic process, and it was also TEA and temperature-dependent with a trend similar to those observed in the free energy of micellization (ΔGm). The degree of disorderliness of the system was also found to be entropy driven at a higher concentration of TEA. The synergistic interaction between the molecules of DETAB–HATAB in the presence of TEA (0.4% v/v) and the spontaneity of the system was at the maximum at 0.1:0.9 mol fraction ratio and the energetics of the system was discussed based on hydrophobic–solvophobic interaction of the monomers in TEA at elevated temperatures.

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