Pretreatment Of Sugarcane Bagasse With Aqueous Ammonia Glycerol Mixtures

Due to its recalcitrant structure,lignocellulose could not be effectively enzymatic hydrolysis by cellulases.Therefore,removing lignin by pretreatment to improve enzymatic efficiency is one of the bottlenecks in comprehensive utilization of lignocellulose.In this work,an efficient ammonia glycerin mixture(AGM)method to improve the digestibility of sugarcane bagasse(SCB)was developed.Response surface methodology was utilized to optimize the AGM parameters to achieve the maximum total fermentable sugar concentration(TFSC)and total fermentable sugar yield(TFSY).Under optimal AGM conditions,13.59 g/L TFSC(pretreatment P1: 9.25% ammonia,1.86 h,180°C)and 0.4449 g/g TFSY(pretreatment P1: 9.51% ammonia,1.78 h,180°C)were achieved,with delignification of 77.81% and 70.91%,respectively.Compared to pretreatment with glycerol or aqueous ammonia,the AGM method significantly enhanced the enzymatic efficiency of SCB.The ammonia recovered from AAWG processes was 3.01 g(from pretreatment P1)or 3.15 g(from pretreatment P2),and the corresponding recovery rate of the ammonia were 32.52% and 33.11%,respectively.Compared with the simultaneous saccharification and fermentation(SSF),the results of fermentations indicated that the separate enzymatic hydrolysis and fermentation(SHF)was more beneficial to increase the ethanol yield.After 6 h of fermentation,the highest ethanol concentration was obtained from P1 pretreated bagasse which was 3.56 g/L,equivalently 116.51 g ethanol per kg of untreated bagasse,and 5.68 times higher than that of the untreated bagasse.The overall results indicate that AGM is effectively used as a pretreatment method for recovering ammonia,which would largely contribute to the economic benefits of biomass biorefinery.