Hexadecane studies, soil removal

Hexadecane Studies. Figure 2 also indicates that the removal of low viscosity liquid soils such as hexadecane (Cj6) is difficult to monitor with this spectroscopic approach because of the rapidity of removal. The run performed with surfactant-free water, however, indicates that a stable C16-water interface is achieved after 5 minutes. The somewhat hydrophobic ZnSe surface of the IRE can be considered a reasonable model of the polyester fabric surface. Water alone cannot completely clean the C16 from the surface, indicating a significant adhesion energy of hydrocarbon to the ZnSe. 

Unlike the experiments carried out below the cloud point temperature, appreciable solubilisation of oil was observed in the time frame of the study, as indicated by upward movement of the oil-microemulsion interface. Similar phenomena were observed with both tetradecane and hexadecane as the oil phases. When the temperature of the system was raised to just below the PITs of the hydrocarbons with C12E5 (45°C for tetradecane and 50°C for hexadecane), two intermediate phases formed when the initial dispersion of Li drops in the water contacted the oil. One was the lamellar liquid crystalline phase La (probably containing some dispersed water). Above it was a middle-phase microemulsion. In contrast to the studies below the cloud point temperature, there was appreciable solubilisation of hydrocarbon into the two intermediate phases. A similar progression of phases was found at 35°C using n-decane as the hydrocarbon. At this temperature, which is near the PIT of the water/decane/C Es system, the existence of a two-phase dispersion of La and water below the middle-phase microemulsion was clearly evident. These results can be utilised to optimise surfactant systems in cleaners, and in particular to improve the removal of oily soils. The formation of microemulsions is also described in the context of the pre-treatment of oil-stained textiles with a mixture of water, surfactants and co-surfactants. 

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