Design and Application of Hydrophobic 2,2,4-Trimethyl-1,3-Pentandiol Deep Eutectic Solvents for Boron Extraction

Narjis Awaja, Ghaiath Almustafa, Ahmad S. Darwish, Ioannis Zuburtikudis, Hadil Abukhalifeh, Hassan A. Arafat, Inas Alnashef

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Recently, new genres of ionic liquids and deep eutectic solvents (DES) have emerged as eco-efficient "designer solvents". Herein, we report the liquification of the water soluble diol 2,2,4-trimehtyl-1,3-pentanediol (TMPD) into a novel hydrophobic DES with thymol or menthol. The intrinsic supercooling properties of the constituents yielded eutectic mixtures with a wide liquid window and superior capabilities for boron extraction. The design framework of the TMPD-based DESs considered multiple criteria in which the trade-offs between the solvents' properties, its boron extraction efficiency and leachability to the aqueous phase were thoroughly mapped. Formation of stable TMPD-boric acid complexes provided exceptional selectivity towards boron extraction from a synthetic brine solution. Thymol:TMPD and Menthol:TMPD at a molar ratio of 2:1 were selected as they exhibited superior extraction efficiencies for boron ('98%) without the drawbacks of lower DES stability or higher DES leachability into the aqueous phase. A remarkably stable performance of the TMPD-based DESs was verified with the sustained boron extraction efficiency over a wide range of pH (2-8), temperature (10-60 °C), aqueous feed boron concertation (100-6000 ppm) (Fig. 1) and most notably, the high A/O mass ratio. The DESs were highly selective for boron in the presence of various co-existing ions, and stable over multiple extraction-stripping cycles. This method of integrating TMPD as the active extracting agent within a DES mixture allows for a higher recovery and better extraction efficiency of boron compared to other traditional LLE systems in which TMPD is diluted with hazardous and volatile organic solvents. The sustainability of these novel solvents allow for its integration into membrane-based separation technologies such as Supported Liquid Membranes.

Original languageBritish English
Title of host publication2021 AIChE Annual Meeting
ISBN (Electronic)9781713852834
StatePublished - 2021
Event2021 AIChE Annual Meeting - Boston, Virtual, United States
Duration: 15 Nov 202119 Nov 2021

Publication series

NameAIChE Annual Meeting, Conference Proceedings


Conference2021 AIChE Annual Meeting
Country/TerritoryUnited States
CityBoston, Virtual


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