Coproduction of cellulosic ethanol, lignosulfonate, and phenolic acids from an integrated corn cob valorization scheme

Abstract

The economic competitiveness of 2G-bioethanol technology should improve through the use of by-products, especially lignin. The present study developed an integrated scheme to produce 2G-bioethanol, lignosulfonate, and phenolic acids from corncobs. Pretreatment with sulfuric acid made it possible to reduce the enzymatic dosage to 5 FPU/g in the enzymatic hydrolysis of samples with a size of less than 20 mesh. The addition of polyethylene glycol 1500 (PEG 1500) boosted the sugar release, reaching 56.73 g/L glucose under conditions with 20% (w/v) solids (gradual addition). In the ethanol production, the semi-simultaneous saccharification and fermentation strategy achieved a maximum production of 31.64 g/L in the condition with 5 FPU/g, 2% (w/w) PEG 1500, and 20% (w/v) solids (gradual addition). FTIR confirmed the preparation of lignosulfonate from fermentation residue, and the surfactant showed good stabilization performance in oil/water systems. Hydrogen peroxide promoted high yields of p-coumaric acid (8045.3 mg/100 g) and ferulic acid (1429.4 mg/100 g) in the alkaline hydrolysis of fermentation residue. Based on the results, corncob is versatile and can be used to create a biorefinery with high economic potential.