Abstract
The removal of myristic acid by aqueous alkyl poly (oxyethylene) ether type nonionic surfactant (CmEOn) solution was conducted by solubilization in surfactant micelles. Actual removal after 24 h by hepta (oxyethylene) ether (C12EO7) solution at various concentration and 30°C was in fair agreement with that calculated, based on the extent to which myristic acid A (sat), linearly related to the concentration of surfactant, could be solubilized. It is thus evident that removed myristic acid soil is solubilized in micelles. Linearity of the reciprocal plot of the Vinit, determined from the slope of the tangent line drawn through the origin (washing time=0), against 1/A (sat) shows that myristic acid soil is removed by the multi-step solubilization mechanism proposed by Shaeiwitz et al.
The effects of temperature on solubilization and removal of myristic acid were studied. At equilibrium, a clear isotropic solution was obtained at 2040°C, while opaque white dispersions were observed at above 45°C. Based on FT-IR measurement, the latter appeared to result from dispersions of ternary liquid crystalline (LC) (myristic acid-C12EO7-water). The removal of myristic acid improved with increase in washing temperature, and after 24 h at 2040°C was quite similar to that calculated from the limit of solubilization. However, above 45°C, actual removal was less than that determined from the extent of LC dispersion.
The effects of change in the structures of nonionic surfactants on the temperature dependency of solubilization of myristic acid were examined by varying the numbers of alkyl (m) and oxyethylene groups (n).
