2024 AIChE Annual Meeting
Evaluating Novel, Amine-Free Switchable Hydrophilicity Solvents
Industries commonly use flammable and toxic volatile organic solvents for reactions, extractions, and separations. They require energy-intensive distillations to be separated, and represent health risks to workers due to their hazards. Switchable Hydrophilicity Solvents (SHSs) offer a solution, as they are able to switch between hydrophilic and hydrophobic behavior using an external trigger, allowing for a non-energy intensive separation. Anionic SHSs specifically use a carboxylic acid that switches between its neutral, hydrophobic state and its anionic, hydrophilic state. The switch is triggered by the addition of a base, which deprotonates the acid and forms a water-soluble salt. This reaction can be reversed by sparging with CO2, which reprotonates the acid making it hydrophobic again. Previous work identified three main issues with current switchable solvents: the surfactant nature of long chain carboxylic acids, high water usage, and toxic counter-ions. Viable SHSs were identified, but the options are few and still limited by their water usage. The main goal of this project is to find new carboxylic acids with switchable behavior and to evaluate possible relationships between the structure and properties of the solvents. Since these novel solvents are not fully understood, studying their structure-property relationship can help develop a framework to identify new alternatives and their appropriate operating conditions for various applications.
