TY - JOUR AU - Kochkodan, Olga AU - Maksin, Victor AU - Antraptseva, Nadiya AU - Semenenko, Tetyana PY - 2020/01/01 Y2 - 2024/03/29 TI - Molecular Interactions in Binary Surfactant Solutions: Effect of pH JF - Periodica Polytechnica Chemical Engineering JA - Period. Polytech. Chem. Eng. VL - 64 IS - 4 SE - DO - 10.3311/PPch.13975 UR - https://pp.bme.hu/ch/article/view/13975 SP - 437-445 AB - <p>By using surface tension and conductivity measurements, the colloid-chemical properties of the mixtures of cationic hexadecylpyridinium bromide with nonionic Triton X-100 surfactants were investigated both in the bulk solution and at air/solution interface at different pH values. The composition of mixed micelles and adsorption layers, parameters of molecular interactions in mixed micelles <em>β<sup>m</sup></em> and adsorption layers <em>β<sup>σ</sup></em>, as well as standard free energies of micelle formation Δ<em>G</em><sup>0</sup><sub><em>mic</em></sub> and adsorption Δ<em>G</em><sup>0</sup><em><sub>ads</sub></em> were calculated. It was found that molecules of the nonionic surfactant presumably dominate in the mixed micelles and adsorption layers. It was shown that <em>β<sup>m</sup></em> and <em>β<sup>σ</sup></em> have negative values, which indicate the strengthening of intermolecular interactions in the mixed micelles and adsorption layers. Based on the data obtained, it was suggested that ion-dipole interactions are involved in the formation of intermolecular structures between nonionic and cationic surfactants in aqueous solution and at the air-solution interface. It was shown that <em>β<sup>m</sup></em>, <em>β<sup>σ</sup></em> as well as Δ<em>G</em><sup>0</sup><em><sub>mic</sub></em> and Δ<em>G</em><sup>0</sup><em><sub>ads</sub></em> parameter depends on the solution pH value. The complex interplay of ion-dipole, protonation and chelation processes, which occur in the surfactant mixtures at different pH and affect the strength of intermolecular interaction, should be taken into account for data analysis.</p> ER -