Thermophysical properties and solubility of different sugar-derived molecules in deep eutectic solvents

\u3cp\u3eDeep eutectic solvents (DESs) are designer solvents analogous to ionic liquids but with lower preparation cost. Most known DESs are water-miscible, but recently water-immiscible DESs have also been presented, which are a combination of hydrogen bond donors and acceptors with long hydrophobic alkyl chains (e.g., decanoic acid + quaternary ammonium salts). These hydrophobic DESs are very interesting as solvents for recovering molecules from aqueous solutions. In this study the solubility of the sugar derived molecules furfural (FF), hydroxymethylfurfural (HMF), dimethyladipate, glucose, fructose, cyclopentanediol, cyclopentanone, and tetrahydrofurfurylalcohol was experimentally screened in six different DESs (five hydrophilic and one hydrophobic) at 30-50-80 °C, for the first time. The Kamlet-Taft parameters of the DESs were also determined, and correlations with the solubility data were established. Moreover, the thermophysical properties (viscosity, decomposition temperature) of the six DESs were measured. All DESs showed Newtonian viscosity behavior. Their thermal stability was good but decreased when sugars were added to the DES phase. The hydrophobic DES had the most interesting solubility properties (highest solubility for FF and HMF, and lowest solubility for the monosaccharides glucose and fructose) and is water-immiscible. Moreover, the hydrophobic DES has the highest Kamlet-Taft π parameter (measure of dipolarity/polarizability ratio) that can be related to the high selectivity for HMF and FF over glucose. Thus, especially the hydrophobic DES is a promising extractant that can be used for selective removal of FF and HMF by liquid-liquid extraction from aqueous biomass solutions, e.g. in biorefineries.\u3c/p\u3

Small-scale screening of novel biobased monomers:the curious case of 1,3-cyclopentanediol

\u3cp\u3eIn this work, we report on the small scale polycondensation and consecutive analysis of novel polyesters based on the potentially renewable 1,3-cyclopentanediol (CPdiol). To avoid evaporation of monomers during thin-film polymerization reactions, trimer pre-polyesters have been synthesized from the corresponding acid-chlorides with diol monomers. Polymerization of these trimers was explored by thermogravimetric analysis to identify potential side reactions, and to assess the ideal polymerization temperature. In general we observe that trans-1,3-cyclopentanediol exhibits good thermal stability up to 200 °C, whereas thermal dehydration of the alcohol end-groups occurs upon further heating. In contrast, for cis-1,3-cyclopentanediol, the ester bonds of the cyclopentane end-groups become labile, thereby generating carboxylic acid end-groups, and 3-cyclopentenol already at 180 °C. The thermal dehydration reactions yield double bond end-groups, which in turn facilitate cross-linking through cross-coupling and Diels-Alder reactions, leading to an increase in molecular weight. Despite the limited thermal stability of CPdiol, here we demonstrate that polymerization of CPdiol can successfully be achieved in thin-film polycondensation conditions at 180 °C, yielding molecular weights well above 10 kg mol\u3csup\u3e−1\u3c/sup\u3e.\u3c/p\u3

Selective separation of furfural and hydroxymethylfurfural from an aqueous solution using a supported hydrophobic deep eutectic solvent liquid membrane

For the first time, 12 different supported deep eutectic solvent (DES) liquid membranes were prepared and characterized. These membranes consist of a polymeric support impregnated with a hydrophobic DES. First, the different membranes were characterized and their stability in water and air was determined. Subsequently, the supported DES liquid membranes were applied for the recovery of furfural (FF) and hydroxymethylfurfural (HMF) from aqueous solutions. The effects of substrate properties (e.g. pore size), DES properties (e.g. viscosity) and concentrations of FF and HMF in the feed phase on the observed diffusivities and permeabilities were assessed. It was found that the addition of DES enhances the transport of FF and HMF through the polymeric membrane support. In particular, the use of the DES consisting of thymol + lidocaine (in the molar ratio 2 : 1) impregnated in a polyethylene support resulted in enhanced transport for both FF and HMF, and is most interesting for (in situ) isolation of FF and HMF from aqueous solutions, e.g. in biorefinery processes

110th Anniversary: Distribution coefficients of furfural and 5-hydroxymethylfurfural in hydrophobic deep eutectic solvent + water systems: experiments and perturbed-chain statistical associating fluid theory predictions

\u3cp\u3eFurfural (FF) and 5-hydroxymethylfurfural (HMF) are intermediates for many products, such as monomers for bioplastics, and can be obtained from various renewable resources. The isolation of these sugar-derived molecules from aqueous solutions is one of the main challenges in biorefinery processes. In the work described in this paper, the separation of FF and HMF from aqueous phases is carried out with hydrophobic deep eutectic solvents (DESs) as new extracting agents. Distribution coefficients of FF and HMF in 10 different hydrophobic DES + water systems have been measured and compared to that of the benchmark extracting agent (toluene). The dependence of the distribution coefficients on the presence of sugars in the system has also been investigated. The hydrophobic DESs were found to selectively extract FF and HMF from aqueous solutions without any co-extraction or precipitation of sugars. Finally, the distribution coefficients have been successfully predicted with PC-SAFT (perturbed-chain statistical associating fluid theory) without the need to fit any parameter to the measured distribution coefficients.\u3c/p\u3

Thermodynamic properties of hydrophobic deep eutectic solvents and solubility of water and HMF in them:measurements and PC-SAFT modeling

\u3cp\u3eRecently, hydrophobic deep eutectic solvents (DESs) were proposed as interesting solvents for biorefinery processes, such as the production of 5-hydroxymethylfurfural (HMF) from glucose in an aqueous environment. Physicochemical property data of hydrophobic DES + water/HMF systems are of utmost importance for process design. In this work, density and vapor pressure of eight different hydrophobic DESs, as well as water solubility and HMF solubility in these DESs were experimentally determined. The solubility was modeled using the pseudo-pure component approach within the framework of Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT). New pure-component parameters for the eight hydrophobic DESs were obtained by fitting to measured density and vapor-pressure data, instead of to density data only. Based on these new pure-component parameters for the DESs, the solubilities of water and of HMF in the hydrophobic DESs were modeled in good agreement with the experimental data at 298 K and atmospheric pressure.\u3c/p\u3

Influence of distribution on the heating of superparamagnetic iron oxide nanoparticles in poly(methyl methacrylate) in an Alternating Magnetic Field

The effect of distribution on the heating of superparamagnetic iron oxide nanoparticles in a polymer matrix has been investigated in an alternating magnetic field. Commercially available particles have been distributed using 30 and 50 wt % loading in a poly(methyl methacrylate) (p(MMA)) matrix by different preparation methods, resulting in different distributions of the particles. Freeze-drying a mixture of ferrofluid and p(MMA) latex followed by compounding is found to diminish particle aggregation, leading to an optimal distribution. Subsequently, the heating of the particles in the nanocomposites has been investigated in an alternating magnetic field of 2850 A m-1 with a 745 kHz frequency. These heating experiments show significantly higher specific absorption rates (SARs) of the incorporated iron oxide particles in the case of the freeze-drying method due to the improved distribution of the particles when compared to direct compounding or solvent casting. Furthermore, the higher particle loading provides faster heating, although the SAR decreases due to the presence of larger aggregates

Removal of alkali and transition metal ions from water with hydrophobic deep eutectic solvents

Hydrophobic deep eutectic solvents were used for the first time for the removal of metal ions from non-buffered water. It was shown that the extraction occurs via an ion exchange mechanism in which all transition metal ions could be extracted with high distribution coefficients, even for high Co2+ concentrations and low DES/water mass ratios. Maximum extraction efficiency could be reached within 5 s and regeneration was possible.\u3cbr/\u3e\u3cbr/\u3

Determination of the total vapor pressure of hydrophobic deep eutectic solvents:experiments and perturbed-chain statistical associating fluid theory modeling

\u3cp\u3eHead-space gas chromatography mass spectrometry (HS-GC-MS) was used for the first time to measure the total vapor pressure of hydrophobic deep eutectic solvents (DESs). The new method was developed as a valid alternative for thermogravimetric analysis (TGA), as TGA did not allow obtaining reliable total vapor pressure data for the hydrophobic DESs studied in this work. The main advantage of HS-GC-MS is that the partial pressure of each DES constituent and the contribution of each DES constituent to the total vapor pressure of the mixture can be measured. The results give a clear indication of the interactions occurring between the DES constituents. Also, activity coefficients, enthalpies of evaporation, and activation energies for fluid displacement were obtained and correlated to the measured vapor pressure data. It was confirmed that the total vapor pressures of the hydrophobic DESs are very low in comparison to vapor pressures of commonly used volatile organic solvents like toluene. The total vapor pressures of the hydrophobic DESs were successfully predicted with perturbed-chain statistical associating fluid theory (PC-SAFT) when using PC-SAFT parameters for the individual DES constituents.\u3c/p\u3