TY - JOUR

T1 - On the fate of deep eutectic solvents after their use as reaction media: the CO2 production during downstream and ultimate disposal

AU - María, Pablo Domínguez de

AU - Kara, Selin

N1 - Funding Information: PDdM acknowledges financial support from the European Union's Horizon 2020 research and innovation programme RADICALZ (grant number: 101000560) is gratefully acknowledged. SK acknowledges Deutsche Forschungsgemeinschaft (DFG, German Research Foundation, grant number: 391127961) for the financial support. This project has received funding from the European Union's Horizon Europe research and innovation program under the Marie Skłodowska-Curie grant agreement no. 101072731. The authors thank Dr Johanna Meyer (Institute of Technical Chemistry, Leibniz University Hannover) for the graphical representations.

PY - 2024

Y1 - 2024

N2 - Deep Eutectic Solvents (DES) have emerged as an alternative for many applications in different chemical sectors (to be used during the upstream and downstream processing, or as performance additives). While traditionally coined as green solvents, the petrochemical and energy-demanding origin of some DES components, together with some reported toxicological data, have been often overlooked. This perspective discusses the possible fate of DES once they have been used as synthetic reaction media, particularly related to the downstream unit to recover the product from the reaction mixture, and to the final DES disposal. The Total Carbon Dioxide Release (TCR) (measured as kg CO 2 per kg product) is used to compare different options. After a downstream processing to recover the product often involving an organic solvent which will be incinerated (producing CO 2), the used DES media can either be incinerated or diluted to some degree to be divested to a Wastewater Treatment Plant (WWTP). A mild wastewater treatment - involving state-of-the-art microbial processing steps, appears more promising than the incineration option, both in terms of CO 2 production, as well as to avoid the potential formation of halide compounds (e.g. from chloride) during the incineration. However, to reach the WWTP, a key factor is the dilution degree of the DES, and the biodegradability that DES (components) may display by wastewater microorganisms. At a range of 1 : 20 dilution, a production of ∼16 kg CO 2 per kg product may be expected in the WWTP, for a synthesis in DES containing 100 g substrate loading per L. Research is urgently needed to assess whether the treatment of DES as diluted wastewater may be a sustainable (and economic) solution for the DES fate.

AB - Deep Eutectic Solvents (DES) have emerged as an alternative for many applications in different chemical sectors (to be used during the upstream and downstream processing, or as performance additives). While traditionally coined as green solvents, the petrochemical and energy-demanding origin of some DES components, together with some reported toxicological data, have been often overlooked. This perspective discusses the possible fate of DES once they have been used as synthetic reaction media, particularly related to the downstream unit to recover the product from the reaction mixture, and to the final DES disposal. The Total Carbon Dioxide Release (TCR) (measured as kg CO 2 per kg product) is used to compare different options. After a downstream processing to recover the product often involving an organic solvent which will be incinerated (producing CO 2), the used DES media can either be incinerated or diluted to some degree to be divested to a Wastewater Treatment Plant (WWTP). A mild wastewater treatment - involving state-of-the-art microbial processing steps, appears more promising than the incineration option, both in terms of CO 2 production, as well as to avoid the potential formation of halide compounds (e.g. from chloride) during the incineration. However, to reach the WWTP, a key factor is the dilution degree of the DES, and the biodegradability that DES (components) may display by wastewater microorganisms. At a range of 1 : 20 dilution, a production of ∼16 kg CO 2 per kg product may be expected in the WWTP, for a synthesis in DES containing 100 g substrate loading per L. Research is urgently needed to assess whether the treatment of DES as diluted wastewater may be a sustainable (and economic) solution for the DES fate.

UR - http://www.scopus.com/inward/record.url?scp=85185501166&partnerID=8YFLogxK

U2 - 10.1039/d4su00021h

DO - 10.1039/d4su00021h

M3 - Article

VL - 2

SP - 608

EP - 615

JO - RSC Sustainability

JF - RSC Sustainability

SN - 2753-8125

IS - 3

ER -