Benzalkonium Chloride Micellization: Salt and Temperature Dependence (Conductivity, Surface Tension)

The aggregation behavior of cationic surfactant (Benzalkonium chloride (BKC)), in the absence and presence of KCl and MgSO4 in aqueous media, was investigated at room temperature by surface tension measurements and at different temperatures by conductivity measurements. Critical micelle concentration (CMC), micelle ionization degree (α), the thermodynamic parameters (standard Gibb's energy of micellization (ΔGomic), enthalpy of micellization (ΔHomic), and entropy of micellization (ΔSomic)), and interfacial parameters were determined. In addition, the geometry of formed micelles was investigated. The effect of magnesium sulfate on BKC micellization was more pronounced compared to potassium chloride. At all temperatures, BKC's CMC values were lower with magnesium sulfate than with potassium chloride. Similarly, the CMC and α values were directly proportional to temperature.