Comparison of the effects of different pretreatments on the structure and enzymatic hydrolysis of Miscanthus.

Miscanthus is regarded as a desired bioenergy crop with enormous lignocellulose residues for biofuels and other chemical products. In this study, the effect of different pretreatments (including microwave, NaOH, CaO, and microwave + NaOH/CaO) on sugar yields was investigated, leading to largely varied hexose yields at 4.0-73.4% (% cellulose) released from enzymatic hydrolysis of pretreated Miscanthus residues. Among them, the highest yield of 73.4% for hexoses was obtained from 12% NaOH (w/v) solution pretreatment, whereas 1% CaO (w/w) and microwave pretreatment resulted in a lower hexose yield than the control (without pretreatment). The sugar yield from microwave followed with 1% NaOH pretreatment was 4.3 times higher than that of microwave followed with 1% CaO. However, the enzymatic hydrolysis efficiencies of the sample were 15.2% and 58.5% under microwave pretreatment followed by 12% NaOH or 12.5% CaO, respectively, which were lower than those of the same concentration of alkali (NaOH and CaO) pretreatments. To investigate the mechanism of varied enzymatic saccharification under different pretreatments, the changes in the surface structure and porosity of the Miscanthus-pretreated lignocelluses were studied by means of Fourier transform infrared, Congo red staining, and scanning electron microscopy analysis. The results show that the different pretreatments destroy the cell wall cladding structure and reduce the bonding force between cellulose, hemicellulose, and lignin to different degrees, therefore increasing the accessibility of cellulose and enhancing cellulose digestion.

[Progress in applying surfactants to lignocellulose hydrolysis for sugar production].

Lignocellulose is a major biomass resource for the production of biofuel ethanol. Due to its abundance, environmental friendliness and renewability, the utilization of lignocellulose is promising to solve energy shortage. Surfactant can effectively promote the enzymatic hydrolysis of lignocellulose. By discussing the influence and mechanism of different surfactants on the enzymatic hydrolysis, we provide references for finding appropriate surfactants in enzymatic hydrolysis process.