. 2021 Sep 10;24(10):103114. doi: 10.1016/j.isci.2021.103114

Table 4.

Conventional solvent recovery technologies, driving forces, important specifications, and key advantages and disadvantages

Technology	Principle/driving force	Specifications and important conditions	Advantages	Disadvantages	Literature sources
Physical separation

Precipitation	Charge solubility	Antisolvent, supersaturation, temperature, pH change	Low cost, selective removal possible, high yield, can remove dissolved solids	Impurities, coprecipitates	(Green and Perry, 2019; Harvey, 2019; Mersmann and Kind, 1988; Wu et al., 2019)
Sedimentation or decantation	Density gradient, Settling velocity	Size, density, tank depth, residence time	Effective at removing dense particles, cheap to implement	Require large space, must be designed based on maximum volume, cannot remove dissolved solids	(Belter et al., 1988; Green and Perry, 2019; Kwok-Keung and LeChevallier, 2013)
Centrifugation	Settling velocity Centrifugal force	Size, density, angular speed, the ratio of centrifugal to gravitational force, and settling distance	Effective at removing low-density and colloidal particles in a shorter time frame than sedimentation	Energy-intensive, cannot remove dissolved solids, generates high heat, and poses a safety hazard when processing volatile solvents	(Agena et al., 1998; Ambler, 1961; Green and Perry, 2019; Price, 1970; Taulbee and Mercedes Maroto-Valer, 2000)

High-temperature separation

Distillation	Relative volatility	Relative volatility >1.05 Heat of vaporization and energy requirements	Designed for a large variety of flow rates, it can separate a homogeneous fluid mixture	Energy-intensive, difficult to separate azeotropes unless a modification is made	(Diwekar, 2011; Górak and Sorensen, 2014; Green and Perry, 2019; Smith and Jobson, 2000; Towler and Sinnott, 2012)

Membrane processes

Membranes	Particle/molecular size/permeability Sorption/Diffusion Pressure	Pore size, Mol. wt. cut-off, average flux, Pressure gradient, type of membranes – M.F., U.F., NF, and R.O.	Lower energy requirement than distillation, highly selective with products, break azeotropes	Fouling, cannot operate at high temperature, may not be compatible with all solvents	(Green and Perry, 2019; Ho and Sirkar, 1992; Lewis, 1996; van Reis and Zydney, 2007; Xiang et al., 2020)
Pervaporation	Sorption/Diffusion Partial pressure	The heat of vaporization, chemical potential gradient, pressure gradient, average flux, membrane selectivity	Can break azeotropes, separate close-boiling point mixture, lower energy requirement than distillation,	Low-permeate flow rate, reduced membrane stability	(Green and Perry, 2019; Luis, 2018; Shao and Kumar, 2011; Slater et al., 2012b; Zarzo, 2018)

Liquid–liquid extraction

Liquid–liquid extraction	Selective partitioning of solutes	Partition coefficient, the solubility of solutes, low solubility of the added solvent in water	Extracts dissolved solids from solvents, high selectivity, separates azeotrope mixture, does not require high temperature	Solvent-intensive, requires, limited by solubility	(Belter et al., 1988; Birajdar et al., 2014; Green and Perry, 2019; Kennedy and Cabral, 1993; Seader et al., 2010; Towler and Sinnott, 2012; Wu and Tu, 2016)
Aqueous two-phase extraction	Partitioning of solute, bioselectivity	Solubility, the composition of two phases, molecular weight	Highly practical with separating bioproducts	Macromolecule partition differently than smaller molecules	(Asenjo and Andrews, 2012; Benavides et al., 2011; Johansson et al., 1998; Sikdar et al., 1991; Wu et al., 2011)