Adsorptive membranes and resins for acetic acid removal from biomass hydrolysates

The bioconversion of lignocellulosic biomass requires two main steps: cellulose and hemicellulose conversion (hydrolysis) to monosaccharides followed by fermentation of the monosaccharides into the desired products. Pretreatment of the lignocellulosic biomass is required to hydrolyse hemicellulose and separate lignin, reduce cellulose crystallinity and increase the porosity of the material. Acetic acid is frequently produced during the pretreatment of lignocellulosic biomass. Acetic acid strongly influences the bioconversion of sugar containing hydrolysates. Previous studies have used anion exchange resins for acetic acid removal from different hemicellulosic hydrolysates. Here, the efficiency of an anion exchange membrane is compared to that of an anion exchange resin, for acetic acid removal. The results show that the membrane exhibited better performance in terms of dimensionless throughput and product loss.

C/C0 0.8 0.6 Glucose, membrane Xylose, membrane Arabinose, membrane Glucose, resin 0.4 Xylose, resin Arabinose, resin 0.2 An ion exchange membrane and resin were compared for removing acetic acid from DI water and detoxified hemicellulosic hydrolysate. The results show that the acetic acid capacity of the ion exchange membrane is higher than that of the ion exchange resin using both acetic acid in DI water and actual hydrolysate. The ion exchange membrane was better able to concentrate the eluted acetic acid than the resin. Sugar losses appeared to be low. These preliminary results suggest that ion exchange membranes hold promise for providing a more efficient means of removing acetic acid from biomass hydrolysates.