Analysis of Removal Process of Laulic Acid Soil by Aqueous Solution of Sodium Dodecyl Sulfate using Microscopic Image Data

Abstract

Washing process of solid fatty acid soil with surfactant aqueous solution was analyzed using the image data captured by CCD microscope system. Lauric acid and soduim dodecyl sulfate were used as model soil and surfactant, respectively. A small lump of fatty acid was adhered on the inner surface of glass tube and surfactant solution was flowed into the glass tube. Then the area of the interface between fatty acid soil and glass tube was observed using CCD microscope system. The image was recorded as AVI file and extracted as BMP file for analysis use. The removal process in this study can be divided into two patterns; (1) fatty acid soil is separated from the glass tube abruptly, and (2) fatty acid is removed continuously. The moving image of the latter removal pattern was captured and analyzed to clarify the removal mechanism.
The result showed that removal rate calculated from square root of the base area (=length order) varied with time in nearly direct proportion. A side image of the soil was calculated from the base area changes in order to compare with the real initial image, and relatively good similarity was obtained. Therefore the removal rate per unit soil area is expected to be constant in the removal process. This result supports the assumption that the removal mechanism of laulic acid is occurred by solubilization mechanism.