(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) obtained from waste/wastewater using a mixed microbial culture (MMC) usually varies in its properties due to daily variation in the waste/wastewater composition applied as feedstock. In the current study, the average molecular weight (MW) of PHBV was purposely reduced from about 1 MDa to about 200 kDa by drying the PHBV-rich biomass at elevated temperature of 120 °C for 18 h to ease extraction and handling. Furthermore, conversion into value-added chemicals such as trans-crotonic acid (trans-CA) and trans-2-pentenoic acid (2-PA) by thermal decomposition (pyrolysis) benefits from the lower MW. For the extraction of low MW PHBV, the use of the bio-based solvents 2-methyltetrahydroxyfuran (2-MTHF) and dihydrolevoglucosenone (cyrene) was studied. The maximum extraction yield of 62 ± 3 % with purity of > 99 % was achieved with 2-MTHF at 80 °C for an hour with high biomass to solvent ratio of 5 % (g/mL). Cyrene-based extractions resulted in the highest yield of 57 ± 2 % with purity of > 99 % at 120 °C in 2 h with 5 % (g/mL) biomass to solvent ratio. The mass balance closure over the extraction process indicated that about 15 % and 10 % of polymer has remained in the residual biomass after extraction by 2-MTHF and cyrene, respectively. The performance of these new solvents to extract polymers with various average MW was compared to the benchmark extractions using chloroform and dimethyl carbonate (DMC). It was found that for the polymers with low average MW the extraction efficiency of the proposed solvents exceeds the benchmark solvents.@en

Green organic entrainers and natural deep eutectic solvents (NADESs) possessing high boiling points and decomposition temperatures, exhibit considerable potential as advanced materials for green entrainers in extractive distillation. However, there is a wide range of solvents to choose from and their properties are only rarely available for use in process design and simulation. The present study aims to assess the selection parameters and examine the performance of and select green organic entrainers and NADESs for the separation of the close boiling mixture methylcyclohexane-toluene. The evaluation carried out was based on selectivity and relative volatility values obtained by using predictive models. COSMO-RS (a unimolecular quantum chemical calculation) was employed to predict the selectivity at infinite dilution, while group contribution methods such as UNIFAC and modified UNIFAC (Dortmund) were used to predict the relative volatility. According to the calculated results, the selectivity appeared a more important selection parameter than the performance index. The relative volatility prediction using the UNIFAC and UNIFAC Dortmund methods exhibits comparable trends to the selectivity results derived from COSMO-RS. However, the use of UNIFAC and modified UNIFAC (Dortmund) in predicting the relative volatility of NADES containing mixtures is limited due to the absence of functional group parameters. This CAPE study reveals that, based on the calculated selectivity (using COSMO-RS) and relative volatility (using UNIFAC, and modified UNIFAC (Dortmund)), most of the proposed green organic entrainers and NADESs exhibit a higher or comparable selectivity and relative volatility as the benchmark entrainers. This confirms the potential of the evaluated green entrainers with higher selectivity and relative volatility to enhance the design of extractive distillation. Therefore, the cost, energy and water consumption, as well as CO2 emissions in the methylcyclohexane and toluene separation can be reduced.@en