CO2-enhanced extraction of acetic acid from fermented wastewater

The industrial process of recovering fermentation-based volatile fatty acids (VFAs) utilizes H2SO4 to acidify the fermentation broth containing VFA-salts [e.g. Ca(CH3COO)2] to enable formation of molecular VFAs. Molecular VFAs are then recovered by liquid–liquid extraction. However, acidification with H2SO4 results in production of large quantities of salts (e.g. CaSO4). Using CO2 rather than mineral acids for acidification of fermentation broth is an environmentally benign alternative which eliminates salt formation. In this study, CO2 was applied in pressures up to 40 bar to enhance the efficiency of extraction of acetic acid (HAc) from fermented wastewater. HAc extraction under atmospheric conditions was also investigated to obtain benchmarks. The ionic liquid [P666,14][Phos] and trioctylamine (TOA) dissolved in n-octanol were applied as solvents to extract HAc from fermented wastewater model solutions containing HAc (1 wt%) and various salts resulting in pH ranging from 2.8 to 6. A more pronounced increase in extractability of HAc, expressed as HAc distribution (D = [HAc]solvent/[HAc]aqueous), was observed for [P666,14][Phos] with increasing CO2 pressure. A mathematical model taking into account carbonic acid equilibria and dissociation of HAc and salts showed that the measured influence of CO2 cannot be explained by the effect of CO2 on aqueous phase pH. Thus, it may be concluded that the pressurized CO2 has altered the fluid properties of the solvents and made them more accessible for HAc. This suggests that applying pressurized CO2 may enhance extraction efficiency of processes other than those involving extraction of volatile fatty acids

Upgrading Fast Pyrolysis Oil via Hydrodeoxygenation and Thermal Treatment: Effects of Catalytic Glycerol Pretreatment

The effects of stabilizing fast pyrolysis oil (PO) with glycerol via catalytic glycerol pretreatment on upgrading via hydrodeoxygenation (HDO) or thermal treatment (TT) were studied. Nonstabilized (original) fast pyrolysis oil was also upgraded via HDO or TT to obtain benchmarks. Generally, HDO decreases the molecular weight of PO. The major beneficial effect of stabilization with glycerol was reduction in molecular weight of the upgraded oil. However, it was observed that the molecular weight reduction was largely induced by the dilution effect of glycerol/glycerol-derived fragments. It should also be noted that glycerol-consuming reactions via decreasing the carboxylic acid and phenolic contents of PO (e.g., via esterification) may play a role in reducing self-polymerization during HDO or TT. Stabilization of PO with glycerol, however, led to an increase in the yield of aqueous fractions of HDO and TT due to the formation of hydrophilic fragments from glycerol and PO constituents. After HDO, the oil fractions of stabilized and nonstabilized PO exhibited similar H/C and O/C molar ratios, suggesting that oxygen removal from the oil fractions was not significantly affected by stabilization

Comparison of solvent‐based affinity separation processes using C

BACKGROUND: Vapor–liquid and liquid–liquid equilibria of unsaturated and saturated hydrocarbons with the bio-based solvent dihydrolevoglucosenone, trademarked as Cyrene, have been reported recently, aiming at the utilization of the solvent in liquid–liquid extraction (LLX) and extractive distillation (ED). In this work, for a model system comprised of methylcyclohexane (MCH) and toluene (TOL), both LLX-based and ED-based processes were compared over a wide range of compositions based on simulations in AspenPlus V10. An economic evaluation based on total annual costs was performed, and the processes using Cyrene were compared with equivalent processes using the industrial benchmark Sulfolane. RESULTS: In the absence of literature data for Sulfolane–MCH–TOL, additional liquid–liquid extractions were done to facilitate parameter estimation for simulation. The Cyrene-based ED process was found to be more efficient than the Sulfolane-based ED process, primarily at lower (30 mol% the ED process with Cyrene is most economic. This process analysis showed that Cyrene is an appropriate bio-based alternative for Sulfolane as an entrainer for ED processes to separate aromatics and aliphatics

Applications of isothermal titration calorimetry in pure and applied research from 2016 to 2020

The last 5 years have seen a series of advances in the application of isothermal titration microcalorimetry (ITC) and interpretation of ITC data. ITC has played an invaluable role in understanding multiprotein complex formation including proteolysis-targeting chimeras (PROTACS), and mitochondrial autophagy receptor Nix interaction with LC3 and GABARAP. It has also helped elucidate complex allosteric communication in protein complexes like trp RNA-binding attenuation protein (TRAP) complex. Advances in kinetics analysis have enabled the calculation of kinetic rate constants from pre-existing ITC data sets. Diverse strategies have also been developed to study enzyme kinetics and enzyme-inhibitor interactions. ITC has also been applied to study small molecule solvent and solute interactions involved in extraction, separation, and purification applications including liquid-liquid separation and extractive distillation. Diverse applications of ITC have been developed from the analysis of protein instability at different temperatures, determination of enzyme kinetics in suspensions of living cells to the adsorption of uremic toxins from aqueous streams