Preparation and physicochemical characterization of deep eutectic solvents and ionic liquids for the potential absorption and biodegradation of styrene vapors.

Styrene emissions can be treated by physicochemical, biological, or physicochemical/biological means. Due to its low solubility in water an alternative to eliminate styrene emissions from air is the use of two-phase partitioning bioreactors (TPPBs) which comprised a hydrophobic non-aqueous phase (NAP) which can improve mass transfer of styrene. This study was devoted to prepare and evaluate the main physicochemical characteristics of novel NAPs such as Ionic liquids (ILs), Deep Eutectic Solvents (DESs) and Natural Deep Eutectic Solvents (NADEs) as well as their toxicity and biodegradability to treat styrene vapors. Absorption experiments of styrene showed that the best NAPs were the DESs formed with Tetrabutylammonium bromide and decanoic acid and the ILs [Cmim][FAP], [Cmim] [NTf] and [Cmim] [PF], since they presented a styrene partition coefficient between 0.0015 and 0.0041. Finally, the IL [Cmim][FAP] was used as a NAP in a TPPB batch process given its high styrene affinity, low solubility in water and non-biodegradability; styrene mineralization was three times higher in the TPPB compared with the control. ILs are potential adjuvant phases in biological degradation systems, as well as other solvents like DESs and NADESs.