Department of Chemistry
Master of Science
Surfactant mediated extractions are analogous to liquid-liquid extractions (LLE) except surfactants are used as extractants instead of organic solvents. The benefit for using surfactants for extractions includes lower toxicity, lower associated costs and direct compatibility with high performance liquid chromatography techniques. In this study, a novel immobilized surfactant extraction method was developed. In this method, the cationic alklytrimethylamrnonium surfactants are immobilized onto a strong cationic exchange resin through ion exchange. This surfactant-resin material is placed in a column and aqueous solutions containing analytes are passed through. The analytes are retained by the long carbon chain of the surfactant molecules and by the sulfonic acid group site on the cationic resin. By adding saturated sodium chloride solution, the resin is converted into the sodium form, and the analytes and surfactant molecules subsequently elute from the column. The solution is collected. By adding an appropriate amount of cosurfactant to the solution, a biphasic solution forms, consisting of aqueous and surfactant rich layers. Almost all the surfactant molecules trapped with analytes will move to the upper surfactant rich phase. The analytes are concentrated in this manner. An aliquot of the surfactant-rich phase is then injected into a high performance liquid chromatograph for analysis. In this research work, the surfactant molecules were confirmed to be bounded on ion exchange resin readily. The relationship between the amount of surfactant bounded on resin and the exchange reaction time was determined. The resin mesh size, resin pretreating time, and sample flow rate were investigated. The effectiveness of this procedure was tested using seven chlorophenols as trace samples. The recoveries for selected chlorophenols were as high as 90 percent. The detection limits were as low as 10-parts-per billion. The effect of water hardness on the extraction efficiency was also investigated. The possible mechanism of this novel extraction technique is discussed.
Zhu, Ming, "An Immobolized Surfactant Extraction Technique Compatible with High Performance Liquid Chromatography-Ultraviolet Visible Detection" (1999). Masters Theses & Specialist Projects. Paper 765.