Date of Award


Degree Name

Master of Science


Geological and Environmental Sciences

First Advisor

Dr. Daniel P. Cassidy

Second Advisor

Dr. Duane R. Hampton

Third Advisor

Dr. David Barnes


Saponins, surfactants, biosurfactant, solubility, enhancement

Access Setting

Masters Thesis-Open Access


Applications of surfactant technology in the environmental remediation industry can greatly enhance the success of non-aqueous phase liquid (NAPL) remediation. Saponins derived from the bark of the Quillaja soapbark tree were evaluated as an alternative natural surfactant. Properties including the critical micelle concentration, emulsion kinetics and the solubilization enhancement of sixteen PAHs (polycyclic aromatic hydrocarbons) were measured. The critical micelle concentration (CMC) for Quillaja saponin was found to be 60 mg/L. Soil contaminated with NAPL from a former manufactured gas plant was used to evaluate saponin’s ability to enhance the solubilization of PAHs commonly found in NAPL. Although solubilization enhancement was observed for all of the PAHs analyzed, the greatest enhancements occurred for PAHs having a larger number of aromatic rings. The solubilization enhancement data were, in turn, used to quantify the solubilization capacity of saponins and shown to have a strong correlation with the intrinsic properties of the PAHs. A novel determination was made with respect to emulsion kinetics. The optimal resting period determined by this research to maximize the effectiveness of saponins was found to be approximately 14 days. Overall, this research showed that saponins are an effective alternative for NAPL remediation