Removal and recovery of furfural, 5‐hydroxymethylfurfural, and acetic acid from aqueous solutions using a soluble polyelectrolyte

Abstract

In the cellulosic ethanol process, furfural, 5-hydroxymethylfurfural (HMF), and acetic acid are formed during the high temperature acidic pretreatment step needed to convert biomass into fermentable sugars. These compounds can inhibit cellulase enzymes and fermentation organisms at relatively low concentrations (≥ 1 g/L). Effective removal of these inhibitory compounds would allow the use of more severe pretreatment conditions to improve sugar yields and lead to more efficient fermentations; if recovered and purified, they could also be sold as valuable by-products. This study investigated the separation of aldhehydes (furfural and HMF) and organic acid (acetic acid) inhibitory compounds from simple aqueous solutions by using polyethyleneimene (PEI), a soluble cationic polyelectrolyte. PEI added to simple solutions of each inhibitor at a ratio of 1 mol of functional group to 1 mol inhibitor removed up to 89.1, 58.6, and 81.5 wt% of acetic acid, HMF, and furfural, respectively. Furfural and HMF were recovered after removal by washing the polyelectrolyte/inhibitor complex with dilute sulfuric acid solution. Recoveries up to 81.0 and 97.0 wt% were achieved for furfural and HMF, respectively. The interaction between PEI and acetic acid was easily disrupted by the addition of chloride ions, sulfate ions, or hydroxide ions. The use of soluble polymers for the removal and recovery of inhibitory compounds from biomass slurries is a promising approach to enhance the efficiency and economics of an envisioned biorefinery.

Physico-Chemical Alternatives in Lignocellulosic Materials in Relation to the Kind of Component for Fermenting Purposes

“…The polyelectrolyte may preferentially react or form a complex with non-inhibitory compounds, thus reducing the number of active sites available for removing the inhibitory compounds; we have already shown that chloride or sulphate ions interfere with the removal of acetic acid using PEI [160]. Similarly, inhibitory compounds might also interact with other species in solution, which could alter their ability to interact with the polymer [60].…”

“…Polethyleneimine (PEI) is a soluble secondary amine cationic polymer, commonly used as a flocculating agent to precipitate cellular debris and other insoluble solids. It has been evaluated for removal of suspended solids from biomass slurries [161] and Carter et al [60,160] studied the efficiency of PEI to remove furfural and HMF from clarified pre-enzymatic hydrolysis liquor [43]. …”

Release of potentially fermentable sugars during dilute acid treatments of Bermuda grass NK37 (Cynodon dactylon)for second-generation ethanol production

“…Both liquid and solid phases were analyzed in order to determine the optimum pretreatment conditions, which generated the maximum possible amounts of hydrolyzed sugars and the least quantities of inhibitors since they inhibit both celullase enzymes and the microorganism …”

“…Hydrolysis was performed following the protocol of Hsu with slight modifications. Briefly, all the grass material was stove conditioned at 105 °C overnight, placed in a desiccator for 15 min and weighed in an analytical balance until constant weight was achieved.…”

Assessment of holocellulose for the production of bioethanol by conserving Pinus radiata cones as renewable feedstock

“…The generation of fermentation inhibitors like acetic acid, hydroxy methyl furfural, furfural, glycol aldehyde and soluble phenolic compounds is also a prominent issue to be solved (Cavka et al, 2011;Sanda et al, 2011;Carter et al, 2011a, b;Raghu et al, 2011;Yong-Jin et al, 2011;Lee et al, 2011;Huang et al, 2011;Zhang et al, 2011;Bellido et al, 2011;Geddes et al, 2011;Sainio et al, 2011;Jayakody et al, 2011). A variety of biomass (cashew apple pulp, coffee pulp waste, switch grass, oil palm empty fruit bunches, seaweeds, bamboo, sugar-cane tops) are being examined as economically viable feedstock for the production of bioethanol (Sindhu et al, 2011;Zhao-Yong et al, 2011;Shenoy et al, 2011;Martin and Grossmann, 2011;Han et al, 2011;Yanagisawa et al, 2011aYanagisawa et al, , 2011b.…”