Micellization and surface properties of Triton X 100 in aqueous solution of short-chain alcohols

Abstract

This study investigates the micellization and surface properties of nonionic surfactant Triton X-100 (TX100) in binary water-alcohol mixtures containing methanol (MeOH), ethanol (EtOH), and 1-propanol (1-PrOH) at 293.15 K. Binary mixtures with alcohol volume fractions (VF) of 0.10, 0.20, 0.30, 0.40 and 0.50 were prepared. Surface tension measurements were carried out to determine the critical micelle concentration (CMC) and surface properties, including maximum surface excess concentration (Γmax), minimum area per molecule (Amin), surface pressure (πcmc) Gibbs free energy of adsorption (ΔGadso) and Gibbs free energy of micellization (ΔGmo). The results show that alcohol addition significantly influences micellization and interfacial behavior. CMC increased with increasing VF of alcohol, reflecting reduced hydrophobic interactions and a decline in polarity of medium. Above 0.30 VF of EtOH and 0.20 VF of 1-PrOH, formation of micelle ceases, indicating suppressed micellization due to extensive disturbance of water's hydrogen-bonding network, reduced cohesive energy density (CED), and dominance of alcohol-surfactant interactions. Surface properties reveal a decline in Γmax and πcmc, alongside an increase in Amin conforming reduce adsorption efficiency. Thermodynamic analysis shows that both ΔGmo and ΔGadso becomes less negative with increasing alcohol content, indicating unfavorable micelle formation and adsorption. These findings suggest that solvent parameters, such as the Gordon Parameter (GP) and CED play a critical role in modulating surfactant behavior in mixed solvent systems.

Keywords

• Surface tension
• Triton X 100
• Short chain alcohol
• Gordon parameter
• Cohesive energy density
• Micellization