This study explores a binary solvent system composed of biobased Cyrene and its derivative Cygnet 0.0 for application in membrane technology and in biocatalytic synthesis of polyesters. Cygnet‐Cyrene blends could represent viable replacements for toxic polar aprotic solvents. The use of a 50 wt % Cygnet‐Cyrene mixture makes a practical difference in the production of flat sheet membranes by nonsolvent‐induced phase separation. New polymeric membranes from cellulose acetate, polysulfone, and polyimide are manufactured by using Cyrene, Cygnet 0.0, and their blend. The resultant membranes have different morphology when the solvent/mixture and temperature of the casting solution change. Moreover, Cyrene, Cygnet 0.0, and Cygnet‐Cyrene are also explored for substituting diphenyl ether for the biocatalytic synthesis of polyesters. The results indicate that Cygnet 0.0 is a very promising candidate for the enzymatic synthesis of high molecular weight polyesters.
A more sustainable dialysis and water filtration membrane has been developed, by using the new, safer, bio-based solvent Cyrene® in place of N-methyl pyrrolidinone (NMP). The effects of solvent choice, solvent evaporation time, the temperature of casting gel, and coagulation bath together with the additive concentration on porosity and pore size distribution were studied. The results, combined with infrared spectra, SEM images, porosity results, water contact angle (WCA), and water permeation, confirm that Cyrene® is better media to produce polyethersulfone (PES) membranes. New methods, Mercury Intrusion Porosimetry (MIP) and NMR-based pore structure model, were applied to estimate the porosity and pore size distribution of the new membranes produced for the first time with Cyrene® and PVP as additive. Hansen Solubility Parameters in Practice (HSPiP) was used to predict polymer-solvent interactions. The use of Cyrene® resulted in reduced polyvinylpyrrolidone (PVP) loading than required when using NMP and gave materials with larger pores and overall porosity. Two different conditions of casting gel were applied in this study: a hot (70°C) and cold gel (17°C) were cast to obtain membranes with different morphologies and water filtration behaviours.
Hesperidin
and rutin are two sought-after natural flavonoids, traditionally extracted
from abundant natural citrus fruits and tea leaves using large amounts
of ethanol or methanol solvents. Recent trends in extractions have
focused on minimizing the use of solvents and creating simpler cost-effective
processes. This study aims to apply the concept of chemical valorization
in the context of a circular economy, by using agro-industrial waste
and biobased alternatives to traditional solvents, which are of environmental
concern. We use minimum amounts of solvent/sample (5 mL/0.25 or 0.5
g) to extract hesperidin and rutin in a single-stage solid–liquid
extraction. Thirty individual solvents and HSPiP were applied to find
the best solvents/blends for extraction. The type of solvent, sample
preparation, maceration time, and extraction temperature were studied.
Results showed that the biobased solvent Cyrene is very effective
when mildly heated to 65 °C (up to 91%) or mixed with water.
Adding water to Cyrene forms its geminal diol hydrate, this enhances
the solubility and extraction of hesperidin and rutin up to ten times
than those of the original pure ketone form. Quantitative sustainability
metrics from the CHEM21 Toolkit demonstrated that our extraction methodology
is environmentally friendly and offers future potential of isolation
of other flavonoids.
Short-chain
oxymethylene dimethyl ethers (OMEs) (molecular formula:
H3CO–(CH2O)
n
–CH3, where n = 3–5) have
previously been studied as diesel-like fuels and fuel additives. OMEs
can be produced from sustainably sourced methanol, and tests indicate
that they are neither genotoxic nor mutagenic. In this report, their
potential as solvents has been investigated to expand the bio-derived
solvent space. According to traditional solvatochromic parameters,
a commercial mixture of OME3–5 and its individual
components (OME3, OME4, and OME5)
have solvation properties similar to problematic industrial ether
solvents such as 1,4-dioxane. Peroxide formation, one of the chief
dangers of classical ether solvents, was found to occur much more
slowly in OMEs than in conventional solvents such as tetrahydrofuran
(THF), demonstrating an improved safety profile. The commercial OME3–5 mixture was found to be broadly miscible with organic
solvents but immiscible with water, suggesting potential application
in aqueous extractions. It performed well in the dissolution of polystyrene
and removal of paints and coatings, indicating OME3–5 may suitable to replace dichloromethane in polymer recycling, polymer
welding, and cleaning applications. To further demonstrate applicability
as a solvent, this mixture was shown to facilitate a model Suzuki
coupling reaction at rates similar to cyclopentyl methyl ether, which
is currently marketed as a green ether. Finally, OME3–5 proved a suitable solvent for enzymatic polymerization, giving high
yields, moderately high degrees of polymerization, and remarkably
narrow dispersity values.
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