Optimization of sulfuric acid-assisted glycerol pretreatment of sugarcane bagasse

Abstract

A combined pretreatment of sugarcane bagasse with glycerol and sulfuric acid was investigated based on a central composite rotatable experimental design. The following factors were varied: temperature (150 -199 ° C), time (0.69 -2.3 h), H 2 SO 4 concentration (0.0 -1.1 % ), and glycerol concentration (55.4 -79.6 % ). Xylans and lignin were considerably solubilized during pretreatment. Xylan solubilization, ranging between 6 % and 94 % , increased significantly with the increase of temperature, time, and H 2 SO 4 concentration and dropped with the increase of glycerol amount. Glycerol restricted the solubilization and full hydrolysis of xylans and the degradation of xylose. Lignin solubilization (20.6 -49.4 % ) increased with the increase of all the experimental factors. Cellulose recovery, which was generally high, increased with the increasing of glycerol concentration and declined at high levels of the other factors. Recoveries above 97 % were achieved at low H 2 SO 4 concentration and high glycerol load, whereas the lowest value (83.4 % ) was achieved in the longestlasting experiment. The models based on the experimental results predicted the maximal lignin solubilization at 187.7 ° C, 2.3 h, 79.6 % glycerol, and 0.64 % H 2 SO 4 , whereas the highest yield of enzymatic hydrolysis can be expected at 194.1 ° C, 1.67 h, 79.6 % glycerol, and 1.1 % H 2 SO 4 . The optimal conditions were confirmed in control experiments. The synergistic effect of sulfuric acid and glycerol on the enzymatic hydrolysis of cellulose was demonstrated.

Acid-Catalyzed Glycerol Pretreatment of Sugarcane Bagasse: Understanding the Properties of Lignin and Its Effects on Enzymatic Hydrolysis

“…The delignification results of the AG pretreatments in the present study were consistent with our previous results, 11 but lower than those from several other studies on AG pretreatment. 10,13 The different observations are largely attributable to the different pretreatment conditions, especially pretreatment temperatures. For example, in a recent study, AG pretreatment of sugarcane bagasse at 200 °C for 15 min with 0.6% H 2 SO 4 (on fibre) led to 52% delignification and a glucose yield of 68%.…”

Effects of glycerol on enzymatic hydrolysis and ethanol production using sugarcane bagasse pretreated by acidified glycerol solution

“…Glycerol has been used as a standalone solvent, or in combination with alkaline catalysts such as Na 2 CO 3 and NaOH, for delignification (Demirbas ß, 1998;Fu and Mazza, 2011a,b;Novo et al, 2011) and pretreatment of lignocellulosic biomass Chen, 2007, 2008; Wang et al, 2015). Furthermore, recent studies showed that acidified glycerol solutions were very effective in deconstructing lignocellulosic biomass to generate materials with high glucan enzymatic digestibilities (Liu et al, 2010b;Martin et al, 2011Martin et al, , 2013. The authors have previously developed an acid-catalysed and glycerol-based pretreatment process and scaled up this process for pretreatment of sugarcane bagasse from laboratory-scale to pilot-scale (Zhang et al, 2013b).…”

Low temperature pretreatment of sugarcane bagasse at atmospheric pressure using mixtures of ethylene carbonate and ethylene glycol

“…[16][17][18][19][20][21][22][23][24][25] Researchers have found that pretreatment with acid-catalysed glycerol or EG solution was more effective than that with polyol alone or alkali-catalysed polyol solution for the pretreatment of lignocellulose. [26][27][28] The disadvantage of these pretreatment systems is that they require relatively high pretreatment temperatures (158-225 °C) in order to achieve cellulose enzymatic digestibility of >90%. [26][27][28][29][30] The initial work by Yamada and Ono established that lignocellulosic biomass can be liquefied in alkylene carbonates, e.g.…”

“…[26][27][28] The disadvantage of these pretreatment systems is that they require relatively high pretreatment temperatures (158-225 °C) in order to achieve cellulose enzymatic digestibility of >90%. [26][27][28][29][30] The initial work by Yamada and Ono established that lignocellulosic biomass can be liquefied in alkylene carbonates, e.g. ethylene carbonate (EC) and propylene carbonate (PC) in the presence of an acid catalyst.…”