title: Effect of phosphoric acid pretreatment on enzymatic hydrolysis of microcrystalline cellulose.
abstract: Microcrystalline cellulose (MCC) was pretreated with phosphoric acid at 323K for 10h. X-ray diffraction (XRD) and Atomic Force Microscope (AFM) analyses revealed that the fiber surface morphology of pretreated MCC (P-MCC) were uneven and rough with the crystalline diffraction peaks of P-MCC decreased to a distinct range. The X-ray Photoelectron Spectroscopy (XPS) analysis showed that the uneven and rough surface of P-MCC could enhance the adsorption of cellulose to the molecular surface of cellulose, which is one of the key factors affecting enzymatic hydrolysis of cellulose. A reversible first order kinetics was employed to describe the adsorption kinetics of cellulase to MCC and P-MCC, and the adsorption rate constants of MCC and P-MCC were found to be 0.016, 0.024, 0.041, and 0.095, 0.149, 0.218min(-1), respectively at 278K, 293K and 308K. The activation energies of MCC and P-MCC hydrolysis reactions were found to be 22.257 and 19.721kJ mol(-1). The major hydrolysis products of MCC and P-MCC were cellobiose and glucose. Hydrolysis of MCC for 120h resulted in yields of glucose (7.21%), cellobiose (13.16%) and total sugars (20.37%). However, after the pretreatment with phosphoric acid, the corresponding sugar yields resulted from enzymatic hydrolysis of P-MCC were increased to 24.10%, 41.42%, and 65.52%; respectively, which were 3.34, 3.15, and 3.22 times of the sugars yields from enzymatic hydrolysis of MCC.
authors.affiliation: State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, 510641, China.
authors.forename: Juanhua
authors.initials: J
authors.lastname: Zhang
authors.forename: Beixiao
authors.initials: B
authors.lastname: Zhang
authors.forename: Jingqiang
authors.initials: J
authors.lastname: Zhang
authors.forename: Lu
authors.initials: L
authors.lastname: Lin
authors.forename: Shijie
authors.initials: S
authors.lastname: Liu
authors.forename: Pingkai
authors.initials: P
authors.lastname: Ouyang
mesh_terms: D000327:Adsorption; D001709:Biotechnology / Q000379:methods*; D002475:Cellobiose / Q000737:chemistry / Q000378:metabolism; D002482:Cellulose / Q000737:chemistry* / Q000378:metabolism; D005947:Glucose / Q000737:chemistry / Q000378:metabolism; D006868:Hydrolysis; D010756:Phosphoric Acids / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D013499:Surface Properties
chemical_list: D010756:Phosphoric Acids; D002475:Cellobiose; D002482:Cellulose; C030242:phosphoric acid; D005947:Glucose; C109691:microcrystalline cellulose