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Development of energy and resource-efficient processes to convert sustainable agricultural and forestry waste into valuable platform compounds, such as 5-hydroxymethylfurfural (5-HMF), has become an important research area for promoting a bioeconomy. However, separation and purification of 5-HMF from hydrolysate is a major challenge for its large scale industrial production. In this work, a series of novel polar-modified post-cross-linked resins were synthesized by oil/ water suspension polymerization, post-cross-linked, and amination reactions using different monomer/cross-linker ratios. Different mass percentages of toluene were also included as a porogen. The effect of pore structure on the equilibrium capacity of 5-HMF onto resins using both single and ternary-component systems was investigated. The results showed that the post-cross-linked resin with ethylene glycol dimethacrylate/divinylbenzene (at 1:4 w/w) with 100% (w/w) toluene had the largest BET surface area (1075 m 2 /g). The largest 5-HMF equilibrium capacity was 65.8 ± 1.3 mg/g in the single-component system and 57.9 ± 1.3 mg/g in the ternary-component system. Additionally, the maximum selectivity values of 5-HMF-FA and LA-FA are 26.6 and 14.2 on PCL-PDE resin with the 100% toluene mass percentage. Furthermore, the average pore diameter and BET surface areas of the resin played a significant role in the adsorption process of 5-HMF from both single-and ternary-component systems. In all, this research provides an important theoretical and practical screening method for the directed design of adsorbents for 5-HMF separation and purification.

5-hydroxymethylfurfural (5-HMF) is a promising high value-added platform chemical, which can be produced from glucose, fructose, or lignocellulosic biomass via catalysis technology. However, the effective separation of 5-HMF from aqueous solution and actual biomass hydrolysate is still challenging because 5-HMF can be further rehydrated into levulinic acid (LA) and formic acid (FA) under acidic conditions. Herein, the adsorption behavior of glucose and 5-HMF and its follow-up products (LA and FA) from aqueous solutions onto polymeric adsorbents modified with various functional groups (XAD-4, XAD7HP, and XAD761 resins) was systematically investigated. The results showed that XAD761 resin exhibited the highest adsorption selectivity (α5‑HMF/glucose = 42.42 ± 5.84, α5‑HMF/FA = 18.41 ± 0.50, and α5‑HMF/LA = 3.01 ± 0.10) and capacity for 5-HMF (106 mg g–1 wet resin). The adsorption equilibrium was better fitted by the Freundlich isotherm model at the studied range of 5-HMF concentrations. The thermodynamic study and activation energy also revealed that the adsorption process of XAD761 resin for 5-HMF was spontaneous, exothermic, and physical. The kinetic regression results revealed that the kinetic data of 5-HMF was accurately followed by the pseudo-second-order kinetic model. In conclusion, the present study revealed that the potential of phenol formaldehyde resin with hydroxyl groups could be used as an adsorbent for aldehyde organic compounds.

This study applied concentrated xylose (60–250 g/L) medium to produce butanol (acetone butanol ethanol, or ABE). A control batch fermentation of 61 g/L initial glucose using Clostridium beijerinckii P260 resulted in a productivity and yield of 0.33 g/L·h and 0.43 g/g, respectively. Use of 60 g/L xylose in a batch system resulted in productivity and yield of 0.26 g/L·h, and 0.40 g/g, respectively. In these two experiments, the culture fermented 89.3% glucose and 83.6% of xylose, respectively. When ABE recovery was coupled with fermentation for continuous solvent removal, the culture fermented all the added xylose (60 g/L). This system resulted in a productivity and yield of 0.66 g/L·h and 0.44 g/g, respectively. When the sugar concentration was further increased above 100 g/L, only a small fraction of the sugar was fermented in batch cultures without product removal. However, with simultaneous product removal, all the xylose (150 g/L) was fermented provided the culture was fed with nutrients intermittently. In this system, 66.32 g/L ABE was produced from 150 g/L xylose with a productivity of 0.44 g/L·h and yield of 0.44 g/g. Using the integrated culture system allowed sugar consumption to be increased by 300% (150 g/L). The continuous system using xylose as a feed did not sustain and after 36 days (864 h) of fermentation, it produced only 2–3 g/L ABE. Rather, the culture became acidogenic and produced 4–5 g/L acids (acetic and butyric). This study suggested that xylose be fermented in batch reactors coupled with simultaneous product recovery rather than in continuous reactors.