Study On Enhanced Enzymatic Hydrolysis Of Corncob Residues And The Adsorption Mechanism Of Corncob Residues To Cellulase

It is of great significance to utilize agricultural wastes for biorefinery to produce biofuels,which can help to alleviate the energy crisis and environmental problems.However,the recalcitrance of lignocellulosic biomass to enzymes limit the enzymatic hydrolysis and saccharification.Therefore,it is necessary to adopt some appropriate pretreatments to overcome the recalcitrance.In this paper,corncob residues(CRs)were choosen as the raw materials,and the effects of sulfonation pretreatment,PFI refining pretreatment and wet grinding pretreatment on the enzymatic hydrolysis efficiency and the characteristics of CRs were studied.Further,the adsorption mechanism of the pretreated CRs to cellulase was studied,and finally the combination of principal component analysis and multiple linear regression models were established to evaluate the influence of each characteristic of CRs on its adsorption capacity to cellulase.First,the effects of three different pretreatment methods on enzymatic hydrolysis efficiency and characteristics of CRs were studied.The results showed that(1)sulfonation pretreatment can effectively improve the enzymatic hydrolysis efficiency of CRs.The enzymatic hydrolysis efficiency of CRs was increased gradually with the increase of Na2SO3 loading.The optimal loading of Na2SO3 was 4.0%,and the glucose concentration and conversion yield were 27.50 g/L and 82.71%,respectively;(2)the PFI refining pretreatment can improve the enzymatic hydrolysis efficiency of CRs to a certain extent.The optimal revolutions of PFI refining was 10000 r,and the glucose concentration and conversion yield were 22.73 g/L and 68.37%,respectively;(3)the wet grinding can improve the enzymatic hydrolysis efficiency of CRs significantly.With the increase of grinding time,the efficiency of enzymatic hydrolysis was increased significantly,and the specific surface area,water retention value and surface charge density of CRs were also increased rapidly,while the crystallinity degree and surface lignin content were decreased.The glucose concentration and conversion yield reached 32.17 g/L and 96.68%,respectively,when the grinding time was 45 min.Then,the effects of three pretreatment methods were compared.The results show that the enzymatic hydrolysis efficiency of CRs after wet grinding was the highest,the optimum grinding time was 45 min and the optimum grinding concentration was 4.0%.Finally,the adsorption mechanism of CRs with different grinding time to cellulase was studied.The results showed that the isothermal adsorption of CRs to cellulase accords with Langmuir adsorption model,which indicated that it fitted the monolayer adsorption;the adsorption kinetics curve followed the pseudo second order model,indicating that it was chemical adsorption.The influence of each characteristic on the adsorption capacity of CRs was quantitatively analyzed by the combination of principal component analysis and multivariate linear regression models,and the results showed that the average particle size had the greatest influence on the adsorption capacity of CRs to cellulase;the crystallinity degree,specific surface area and surface lignin content had a weaker influence on the adsorption capacity of CRs to cellulase;the water retention value and surface charge density had no significant effect on the adsorption capacity of CRs to cellulase.