Professor Emeritus The University of Oklahoma Norman, Oklahoma, United States
Abstract: In this presentation I provide an overview of my journey into the world of microemulsions, motivated by specific applications which ultimately helped advance fundamental approaches. My first foray into microemulsions sought to expedite aquifer remediation thereby protecting human health. Our objective was to liberate aquifer-trapped oil by interfacial tension reduction and, as needed, advanced solubilization. This research started with bench scale studies, advanced to pilot scale field studies, and ultimately resulted in full scale implementations of surfactant-enhanced aquifer remediation. We next studied microemulsion-based oilseed extraction to replace hexane-based processes. This research was our first foray into working with triglyceride oils which presented unique challenges to microemulsion formation. This work progressed from batch studies to laboratory-based pilot scale studies. Based on what we learned about working with triglycerides we went on to evaluate microemulsion-based vegetable-oil biofuels and detergency of triglyceride-soiled fabrics. All the above research was motivated by the desire to maximize surfactant segregation to the oil-water interface to minimize interfacial tension with the added benefit of maximizing solubilization. Initial efforts were guided by HLB (hydrophilic-lipophilic balance) values along with CPF (critical packing factor) and WRR (Winsor R Ratio) concepts. Limitations in HLB values and difficulty in quantifying parameters in the CPF and WRR concepts led to our focus on the HLD (hydrophilic-lipophilic deviation) approach which has proven to be more robust and comprehensive. For example, we demonstrated that optimal detergency formulations for a range of soils and surfactant systems could be captured by a common range of HLD values. Ongoing research to advance the HLD concept make the future of microemulsion-based formulations and technologies exciting.
