Cellobiose as a Model Carbohydrate for Predicting Solubilities in Nonaqueous Solvents

Abstract

The use of nonaqueous solvents for conversion of biomass molecules into platform chemicals and fuels is hindered by a lack of solubility data and models. Accordingly, the solubility of the model carbohydrate, cellobiose, was measured at 20 °C in 18 organic liquids and water. Solubility ranged from <0.001 g L–1 in hydrocarbon solvents to >100 g L–1 in hydrogen bond acceptor solvents. Three models were analyzed to evaluate accuracy and to understand factors that affect cellobiose solubility: Hansen’s solubility theory (HST), linear free energy relationship (LFER), and several versions of the UNIQUAC functional-group activity coefficients (UNIFAC) model. Cellobiose Hansen solubility parameters (HSPs) were estimated using experimental solubility measurements, but the model was unable to correctly distinguish several of the good solvents from the poor ones. A regressed LFER containing contributions from solvent excess molar refraction, polarizability/dipolarity, acidity, basicity, and molar volume was able to match measured solubilities to within ±2 log units (AAD of 66% and ARD of 27%). The LFER model indicated that good solvents were highly polarizable and had low molar volume, consistent with the good cellobiose solubility observed for water. A modified version of UNIFAC, including an additional association term (A-UNIFAC), predicted the solubility of cellobiose and several other carbohydrates in water and alcohols to within ±0.65 log units (AAD of 25% and ARD of 6.7%), indicating that the A-UNIFAC framework can be used in a predictive manner. This work provides guidance for future studies on the use of nonaqueous solvents for biomass conversion.

Sustainable biomass hydrodeoxygenation in biphasic systems

“…184 Thus, water-oil biphasic systems can increase the strength of hydrogen bonds between molecules and water molecules by forming hydrogen-rich local solvent regions around the OH groups of the reactants, thereby influencing the solubility of the substance and further accelerating the reaction rate. 185,186 Esteban et al 54 reported the selective HDO of sugars from lignocellulose to produce 5-HMF and furfural in a water/MIBK biphasic system, as shown in Fig. 18a.…”

High-Throughput Computational Solvent Screening for Lignocellulosic Biomass Processing

“…The mass of cellobiose recovered in aqueous acid solution is denoted as 𝑚 cellobiose and the mass of solvent in the test solution is given as 𝑚 solv . As the maximum solubility limits of cellobiose were unknown and could vary widely among solvents [90], the dissolution of cellobiose was studied below the saturation point for individual solvents.…”

Suppression Effect of Gamma-Valerolactone on the Mild Alkaline Pretreatment of Hybrid Pennisetum

“…Recently, gamma-valerolactone has been highlighted as a biomass-derived organic solvent that has high dissolution of lignin but low dissolution rate of carbohydrates; , its use in GVL/water and GVL/water/acids has been widely applied for the delignification of lignocellulosic biomass with enhanced performances. − Given the advantages of both alkaline/water and GVL/water for lignocellulosic biomass pretreatment, we hypothesized that the combination of alkaline and GVL can adopt advantages from both sides, leading to a technique that not only improves delignification but also suppresses the loss of carbohydrates. However, trials on the combined GVL/alkaline pretreatment have not been carried out, and the effect of GVL on alkaline delignification remains unknown.…”