Influences of alcohol and diol on the aggregation behaviour, modes of interaction and the thermodynamic properties of the mixture of bromocresol green dye and sodium dodecyl sulphate at numerous temperatures

The aggregation of the mixture of anionic surfactant - sodium dodecyl sulfate (SDS), and an anionic dye - bromocresol green sodium salt (BCG) was investigated by conductometric technique in water and alcoholic/diolic media within a temperature range of 300.55-320.55 K (with 5 K interval). The observed critical micelle concentration (cmc) decreases with surging of the concentration of BCG, following the same trend for beta value. In presence of additives (ethanol, propanol, and ethylene glycol), the cmc value decreases up to a certain concentration and then the cmc values start enhancing with increasing concentration in all the cases. With the increased additive percentage, the beta values continually decrease. Again, the cmc value increases gradually with the increase of temperature both in water and aq. additives media. The free energy of studied aggregation phenomena is negative which experiences an augmentation with the escalation of temperature. The increased negative value of free energy at elevated temperature indicates that the process becomes more spontaneous at a higher temperature. The Delta H-m(0) and Delta S-m(0) values reveal that the probable interaction forces between BCG and SDS are hydrophobic, ion-ion, as well as electrostatic interactions. [GRAPHICS]

Automated summary

The critical micelle concentration of a mixture of anionic surfactant SDS and anionic dye BCG was studied in different media and temperatures. The presence of additives affected the cmc values, initially decreasing and then increasing with concentration. Additionally, the cmc values increased gradually with temperature in all cases, while the beta values decreased with increased additive percentage.