Pressure-Driven Membrane Processes for the Recovery and Recycling of Deep Eutectic Solvents: A Seaweed Biorefinery Case Study

Abstract

Deep eutectic solvents (DES) are green alternatives for conventional solvents. They have gained attention for their potential to extract valuable compounds from biomass, such as seaweed. In this framework, a case study was developed to assess the feasibility of pressure-driven membrane processes as an efficient tool for the recovery of deep eutectic solvents and targeted biomolecules. For this purpose, a mixture composed of the DES choline chloride–ethylene glycol (ChCl-EG) 1:2, water and alginate was made to mimic a DES extraction from seaweed. An integrated separation process design was proposed where ultrafiltration-diafiltration-nanofiltration (UF-DF-NF) was coupled. UF and DF were found to be effective for the separation of alginate with an 85% yield. DES was likewise recovered by 93%, proving the membrane filtrations’ technical feasibility. The NF performance to separate the DES from the water, for its recycling, laid by a 45%-50% retention and a final concentrated DES solution of 18%(v/v).

Keywords: Deep eutectic solvents, biorefinery, membrane processes, ultrafiltration, nanofiltration, seaweed.