Removal of fermentation inhibitors from pre-hydrolysis liquor using polystyrene divinylbenzene resin

Abstract

Background The presence of soluble lignin, furfural and hydroxymethylfurfural (HMF) in industrial pre-hydrolysis liquor (PHL) from the pulping process can inhibit its bioconversion into bioethanol and other biochemicals. Although various technologies have been developed to remove these inhibitors, certain amounts of sugars are also inevitably removed during the treatment process. Hence, polystyrene divinylbenzene (PS-DVB) resin was used as an adsorptive material to simultaneously remove fermentation inhibitors while retaining sugars with high yields to improve the fermentability of PHL after acid hydrolysis by enriching its xylose concentration. The fermentability of acid-hydrolyzed PHL (A-PHL) was evaluated by the bioconversion into ethanol and xylosic acid (XA) after treatment with PS-DVB resin. Results The results showed that the highest xylose concentration (101.1 g/L) in PHL could be obtained by acid hydrolysis at 100 °C for 80 min with 4% acid, while the concentration of fermentation inhibitors (furfural, HMF and lignin) in PHL could also be significantly improved during the acid-hydrolysis process. After treatment with PS-DVB resin, not only were 97% of lignin, 92% of furfural, and 97% of HMF removed from A-PHL, but also 96% of xylose was retained for subsequent fermentation. With resin treatment, the fermentability of A-PHL could be improved by 162–282% for ethanol production from A-PHL containing 30–50 g/L xylose and by 18–828% for XA production from A-PHL containing 90–150 g/L xylose. Conclusions These results confirmed that PS-DVB resin can remove inhibitors from PHL before producing value-added products by bioconversion. In addition, this work will ideally provide a concept for producing value-added chemicals from pre-hydrolysis liquor, which is regarded as the waste stream in the pulping process.

Comprehensive understanding of the effects of metallic cations on enzymatic hydrolysis of humic acid-pretreated waste wheat straw

“…Individual 0.2 mL aliquots were taken at 2 h, 4 h, 6 h, 12 h, 24 h, 48 h, and 72 h. Each sample was frozen and preserved until further analysis. The collected samples were centrifuged at 10,000 rpm for 5 min to obtain a supernatant which was analyzed for sugars by HPLC (Agilent 1260 Series) [ 47 ]. Enzymatic hydrolysis efficiency of the AWWS was calculated according to the following equation: where 0.9 is the factor that converts glucose to equivalent glucan.…”

Separation and characterization of lignin and sugars in the hydrolysate of hot water extraction of poplar wood by membrane filtration and activated carbon adsorption

“…Acetic acid had the highest concentration, whereas 5-HMF had the lowest concentration among the degradation products. Notably, short time extraction showed a much lower concentration of degradation products than conventional hot water extraction, which lasted over 1 h. Thus, short-time extracts have lower biotoxicity, as these degradation products inhibit the biological fermentation of sugars into biofuels (Huang et al 2020). The acetic acid concentration in conventional hot water extraction was reported to reach 1.6 to 4.1 g/L, which was much higher than the acetic acid concentrations in the extracts of the short-time treatments listed in Table 1.…”

Valorization of Enzymatic Hydrolysis Residues from Corncob into Lignin-Containing Cellulose Nanofibrils and Lignin Nanoparticles

“…Recent studies suggested that converting the cellulose and hemicellulose of biomass to monomeric sugars and biofuels could be a great road to meeting the urgent need for renewable alternative carbon resources (Robertson et al, 2017;Huang et al, 2019;Lin et al, 2019). Among the agricultural wastes, corncob has been widely concerned for its richness in hemicellulose, which is often used to produce xylose, xylitol, xylo-oligosaccharides, or furfural (Si et al, 2009b(Si et al, , 2013bZhang et al, 2014;Hu et al, 2016;Liu et al, 2016;Huang et al, 2020b). However, a large amount of corncob residue is produced and it is usually used for burning to generate heat or electricity, cultivation, feed, or just discarded.…”