Efficient Conversion Of Natural Cellulose Treated By The Coupling Process Of Enzyme And Phosphate-based Ionic Liquid

Cellulosic material is inexhaustible renewable resources in nature, comprehensive andefficient utilization of cellulosic material poses important effect on strategic significanceand practical significance toward alteration and supplement of energy, reducing greenhousegas emissions, protect the ecological environment. Especially cellulose waste energyutilization is expected to alleviate a shortage of energy in our country. Moreover, it has anirreplaceable role in energy saving. Therefore, it has become a hot topic that bio-energy andbio-based chemicals be produced using cellulosic waste as raw material.Firstly, the best ionic liquid was selected to treat straw with surfactant via the researchof dissolving capacity test of ionic liquids, the result of saccharification after treatment onfiber, and its bio-compatibility. The results showed that the ionic liquid1,3-dimethylimidazole dimethyl phosphate salt ([Mmim][DMP]) had better processing capability oncellulosic materials and bio-compatibility. In the pretreatment/saccharification process,[Mmim][DMP] coupling Tween-80to pretreat mulberry powder and bagasse comparingwith [Mmim][DMP] to pretreat mulberry powder and bagasse, the yield of sugars of theregenerated straws saccharified48h improved16.59%,13.10%, respectively, and theanalysis of single factor test and response surface of saccharification after mulberry powderpretreated by [Mmim][DMP]/Tween-80, the obtaining optimum pretreatment conditions:the pretreatment temperature was130oC, the pretreatment time was1h, the mass ratio ofsubstrate and Tween-80was0.90:1, the mass ratio of substrate and [Mmim][DMP] was0.07:1, stirring rate of pretreatment was1500r/min, the yield of reducing sugars was up to80.12%after the regenerated mulberry straw which obtained under the conditionsaccharified48h, the hydrolyzates could be used fermented to produce ethanol with Candidashehatae, ethanol production was got up to0.19g/g reducing sugar within24h. In a word,the selected ionic liquid [Mmim][DMP] which had processing power and bio-compatiblebetter processing capability and bio-compatibility, and could treat cellulosic materials withTween-80, the yield of reducing sugars was up to80.12%after the regenerated strawsaccharified48h.Secondly, in situ saccharification of ionic liquid process, the adding of Tween-80comparing with [Mmim][DMP] in situ saccharification on mulberry powder and bagasse,the yield of sugars improved11.75%,10.28%, respectively. And the analysis of[Mmim][DMP]/Tween-80in situ saccharification on mulberry powder with responsesurface, the obtaining optimum conditions were that the concentration of ionic liquid [Mmim][DMP] was8.9%, pretreatment time was1.10h, the mass ratio of substrate andTween-80was7.47:1, the yield of reducing sugars got to80.07%when mulberry powder insitu saccharification for48h under this condition. So, this proved that the surfactantTween-80could enhance the process of ionic liquid in situ saccharification on straws.Finally, in situ saccharification was carried out after immobilizing enzyme withgraphene oxide. Graphene oxide immobilized cellulase, pectinase, the dual enzyme mixedin ionic liquid in situ saccharification48h, the yield of sugars were2.87,2.54,3.25mg/mL,respectively. In situ saccharification process, the yield of sugars of the immobilized twoenzymes was higher than the yield of sugars of the immobilized single enzyme, so theinteraction between two enzymes was conducive to the saccharification of mulberry powder.The results showed that the graphene oxide immobilized enzyme had better stability inionic liquid, and the immobilization of dual enzymes could form synergistic effect, whichcould make natural fibrous materials carry out efficient enzymatic conversion.In conclusion, the efficient conversion of natural cellulose could be obtained usingphosphate-based ionic liquid and enzyme coupling process. In this work, natural cellulosicmaterials (e.g. mulberry branches) was used as an alternative raw material,phosphate-based ionic liquids with good biocompatibility was used as alternative solvent,enzyme (cellulase, pectinase) and microbe were used as catalyst, which can deal with threemajor challenges of the green chemical industry, perform green chemical process, andprovide useful process engineering and data for biomass energy.