In a time when the effects of climate change and industrial waste are creating more water stressed areas around the globe, it is crucial to make the best of available water resources in an effective and sustainable manner. Temperature swing solvent extraction is a desalination technique that has shown increasing promise in the past decades, more recently in its effectiveness toward hypersaline brines. The technique employs amine solvents that have characteristic solubility properties which are inversely proportional to temperature. At lower temperatures, a larger amount of water is attracted to the solvent leaving a concentrated raffinate. The amine-water layer, separated from the raffinate, undergoes temperature swing to higher temperatures, and the pure water is extracted from the amine according to the decreased water solubility. In this study, seven different solvents, consisting of secondary and tertiary amines, were chosen to compare the method’s effectiveness for each type of amine, on the calculation basis of volume, mass, and mole ratios between the solvent and water. 1M and 4M salinity was employed to cover the range of relevant hypersaline levels. Yielded product water and its corresponding amine solvent were analyzed to ensure their safety for human consumption as defined by the Environmental Protection Agency, focusing on the efficiency of each extraction. Residual salt content was analyzed using a conductivity meter, and the residual amine content was analyzed using a TOC/TN analyzer. The extracted product water then undergoes a post-treatment (dead-end reverse osmosis) to evaluate the removal efficiency trace amine. Realized trends from gathered data show triethylamine as the solvent that produces the cleanest water strictly after the extraction technique, regardless of calculation basis or salinity. The trends within the TOC/TN analysis were consistent with those from the literature regarding solubility levels amongst the amines used, given differences in their molecular structure.


We would like to acknowledge the financial support from the School of Science and Technology at Georgia Gwinnett College (STEC 4500 grants).

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