One major challenge to our growing society is the extraction of both contaminants and market-value chemicals from water and waste systems. As water becomes a more precious commodity, new methods that clean water and recover precious compounds without wasting further water resources are critical. Hydrophobic materials that can extract compounds from water in a biphasic system can lead to a highly effective and efficient process. Ionic liquids, which are hydrophobic organic salts existing as liquids at room temperature, are tunable organic materials comprised of cations and anions that can be optimized for water immiscibility and extraction efficiency. Ionic liquid extractions can serve as an environmentally friendly method of extraction of compounds from water, including biofuels and rare earth metals as commodity chemicals, or heavy metals and organic compounds that are toxic.<br/>This study focuses on ionic liquids containing phosphonium cations for broad-spectrum extraction of chemicals from water, due to their ability to form separate phases with water allowing for biphasic extraction. The ionic liquids were tested for extraction efficiency of several classes of compounds, including lanthanide and actinide metals, that can easily pollute biological systems and cause adverse effects. These metals have market value as precious metals, but can also be toxic due to radioactivity and heavy metal poisoning. The ionic liquids were also determined to extract large organic compounds, such as biofuels produced by bacteria in water systems, to address alternative solutions to energy production.<br/>As these materials would potentially be used in the extraction from environmental samples, the toxicity of the ionic liquid compounds was assessed on several species of bacteria using zone of inhibition tests. Many of the ionic liquids showed a low toxicity, which can be interpreted as a potential for the use of phosphonium based ILs in biofuel and metal extraction. Ionic liquids therefore present a new approach to broad spectrum extraction processes, including restoration of environmental systems to their standard environment through the extraction of harmful metals or organics, and allow recovery of commodity materials.

Low toxicity extraction solvents for recovery of precious materials and environmental contaminants

253rd National Meeting (2017)

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