2024 AIChE Annual Meeting
The Effect of Amine Location in Six-Carbon Amines on Desalination in Temperature Swing Solvent Extraction
Many industrial processes, as well as water treatment methods such as reverse osmosis and multi-stage flash, result in the creation of high salinity brines as byproducts, which can be up to ten times saltier than seawater. Current methods used to desalinate these solutions, such as thermal distillation, brine concentrators, and crystallization, either have high energy costs or a low through-put. As such, there is renewed interest in finding commercially viable methods to reduce the environmental impacts and costs of brine disposal. Temperature Swing Solvent Extraction (TSSE) is a desalination method that utilizes the temperature-dependence of certain solvents to selectively dissolve water out of brine solutions at lower temperatures and release it at higher ones. The focus of this project is to investigate the performance of six-carbon amine solvents in TSSE with the goal of understanding the structure-property-performance relationships between them. Six-carbon amine solvents have been tested for their desalination and water recovery capabilities using conductivity and mass measurements. Solvent behavior with various brine solutions has been characterized through change in volume, change in temperature, ion electrode, total organic carbon, and Karl-Fischer titration data. Results indicate that inclusion of a secondary amine rather than a primary or tertiary one is critical to the solvent’s ability to selectively intake water over salt ions and release it upon the temperature change, with symmetrical molecules displaying the best desalination capabilities.