Complete recovery of cellulose from rice straw pretreated with ethylene glycol and aluminum chloride for enzymatic hydrolysis

Ethylene glycol (EG) and AlCl3 pretreated rice straw with 100% cellulose remained for enzymatic hydrolysis (94% glucose yield). [Display omitted] •A novel ethylene glycol and aluminum chloride pretreatment was developed.•100% cellulose was recovered with removal of 88% lignin and 90% hemicellulose.•Specific surface area and pore volume increased by 7.3 and 6.8 times.•The enzyme adsorption ability of rice straw rose by 11-folds after pretreatment.•Glucose yield increased by 2 times that for original straw, reaching 94% at 24 h. Rice straw was pretreated with ethylene glycol (EG) and AlCl3 for enzymatic hydrolysis. EG-AlCl3 pretreatment had an extremely good selectivity for component fractionation, resulting in 88% delignification and 90% hemicellulose removal, with 100% cellulose recovered or 76% (w/w) cellulose content in solid residue at 150 °C with 0.055 mol/L AlCl3. The pretreated residue (5%, w/v) presented a higher enzymatic hydrolysis rate (glucose yield increased 2 times to 94%) for 24 h at cellulase loading of 10 FPU/g. The hydrolysis behavior was correlated with the composition and structure of substrates characterized by SEM, FT-IR, BET, XRD and TGA. The enzyme adsorption ability of pretreated straw was 12-folds that for the original sample. EG-AlCl3 solution was further cycled for 3 times with 100% cellulose recovery but only 29% lignin removal due to the loss of AlCl3. EG-AlCl3 pretreatment is an efficient method with little loss of cellulose for lignocelluloses.