ACS Sustainable Chemistry & Engineering, Jan 8, 2020
Dimethyl itaconate (DI), a promising biomass-derived intermediate, cannot be synthesized from ita... more Dimethyl itaconate (DI), a promising biomass-derived intermediate, cannot be synthesized from itaconic acid (IA) in organisms due to the lack of metabolic pathways. It is necessary to develop a gre...
Dimethyl itaconate (DI), a promising biomass-derived intermediate, cannot be synthesized from ita... more Dimethyl itaconate (DI), a promising biomass-derived intermediate, cannot be synthesized from itaconic acid (IA) in organisms due to the lack of metabolic pathways. It is necessary to develop a green and high-efficiency method to synthesis DI from IA. In this study, DI was, for the first time, produced from IA in an aqueous medium by an ionic liquid-strengthened enzymatic method. We found that when pretreated by the ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF 6 ]), the pH tolerance range of the lipase shrunk and the hydrolysis activity of it was greatly inhibited, while its esterification activity was not. Moreover, when the [bmim][PF 6 ]treated immobilized Rhizomucor miehei lipase (RML, 50 mg/mL) was employed in a reaction containing IA/methanol at a molar ratio of 1:30 and methanol/water in a volume ratio of 1:10 at 30°C after 24 h, a 64.3% yield and 73.2% selectivity of DI was obtained. The results of HPLC and GC−MS revealed that in addition to the main product DI, other side products including acetic acid, propionic acid, and itaconic acid cyclolactone were also generated, which indicates that the RML-catalyzed esterification of IA and methanol has various side reactions, such as lactonization and selfdecomposition of IA.
Conversion of lignocellulose to sugars involves two main processes, namely pretreatment and enzym... more Conversion of lignocellulose to sugars involves two main processes, namely pretreatment and enzymatic hydrolysis. Lignocellulose pretreatment leads to the degradation of enzymatic recalcitrance of substrate for achieving efficient saccharification. In this study, liquid hot water (LHW), hydrochloric acid (HCl), and sodium hydroxide (NaOH) were as reagents used to pretreat sugarcane bagasse (SB). Results showed that LHW, HCl, and NaOH pretreatment could solubilize 95.3%, 94.7% xylan and 88.7% lignin, respectively. Enzymatic hydrolysis of pretreated SB showed that the maximum glucose (26.0 g/L) and xylose (12.7 g/L) concentration were produced by NaOH pretreatment, and slightly more glucose and less xylose were produced after HCl pretreatment compared to LHW pretreatment. Addition of Tween 80 or xylanase could significantly improve both glucose and xylose production. At 48 h, the glucose increase for LHW, HC1 and NaOH pretreatment was 38.3%, 26.4% and 8.0%, respectively, and the xylose increase for them was 35.0%, 24.9% and 1.7%, respectively. Fractal-like kinetics showed that the value of rate constant increased after the addition of Tween 80 or xylanase, and the efficiency of enzymatic hydrolysis mainly depended on rate constant other than fractal dimension of substrate. Totally, substrate accessibility was dominated for efficient of lignocellulose to sugar compared to enzyme loading. The application of fractal-like theory on the heterogeneous enzymatic hydrolysis of lignocellulose was quite successful.
ACS Sustainable Chemistry & Engineering, Jan 8, 2020
Dimethyl itaconate (DI), a promising biomass-derived intermediate, cannot be synthesized from ita... more Dimethyl itaconate (DI), a promising biomass-derived intermediate, cannot be synthesized from itaconic acid (IA) in organisms due to the lack of metabolic pathways. It is necessary to develop a gre...
Dimethyl itaconate (DI), a promising biomass-derived intermediate, cannot be synthesized from ita... more Dimethyl itaconate (DI), a promising biomass-derived intermediate, cannot be synthesized from itaconic acid (IA) in organisms due to the lack of metabolic pathways. It is necessary to develop a green and high-efficiency method to synthesis DI from IA. In this study, DI was, for the first time, produced from IA in an aqueous medium by an ionic liquid-strengthened enzymatic method. We found that when pretreated by the ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF 6 ]), the pH tolerance range of the lipase shrunk and the hydrolysis activity of it was greatly inhibited, while its esterification activity was not. Moreover, when the [bmim][PF 6 ]treated immobilized Rhizomucor miehei lipase (RML, 50 mg/mL) was employed in a reaction containing IA/methanol at a molar ratio of 1:30 and methanol/water in a volume ratio of 1:10 at 30°C after 24 h, a 64.3% yield and 73.2% selectivity of DI was obtained. The results of HPLC and GC−MS revealed that in addition to the main product DI, other side products including acetic acid, propionic acid, and itaconic acid cyclolactone were also generated, which indicates that the RML-catalyzed esterification of IA and methanol has various side reactions, such as lactonization and selfdecomposition of IA.
Conversion of lignocellulose to sugars involves two main processes, namely pretreatment and enzym... more Conversion of lignocellulose to sugars involves two main processes, namely pretreatment and enzymatic hydrolysis. Lignocellulose pretreatment leads to the degradation of enzymatic recalcitrance of substrate for achieving efficient saccharification. In this study, liquid hot water (LHW), hydrochloric acid (HCl), and sodium hydroxide (NaOH) were as reagents used to pretreat sugarcane bagasse (SB). Results showed that LHW, HCl, and NaOH pretreatment could solubilize 95.3%, 94.7% xylan and 88.7% lignin, respectively. Enzymatic hydrolysis of pretreated SB showed that the maximum glucose (26.0 g/L) and xylose (12.7 g/L) concentration were produced by NaOH pretreatment, and slightly more glucose and less xylose were produced after HCl pretreatment compared to LHW pretreatment. Addition of Tween 80 or xylanase could significantly improve both glucose and xylose production. At 48 h, the glucose increase for LHW, HC1 and NaOH pretreatment was 38.3%, 26.4% and 8.0%, respectively, and the xylose increase for them was 35.0%, 24.9% and 1.7%, respectively. Fractal-like kinetics showed that the value of rate constant increased after the addition of Tween 80 or xylanase, and the efficiency of enzymatic hydrolysis mainly depended on rate constant other than fractal dimension of substrate. Totally, substrate accessibility was dominated for efficient of lignocellulose to sugar compared to enzyme loading. The application of fractal-like theory on the heterogeneous enzymatic hydrolysis of lignocellulose was quite successful.
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