Obtaining valuable components of fuels and petrochemical products from vegetable raw materials is complicated by its complex structure. To reduce energy consumption and increase the yield of desired products biomass pretreatment is used, during which partial removal of lignin and hemicellulose takes place. The use of irradiation causes destruction of intermolecular and intramolecular bonds within the structure of the lignocellulosic materials, which leads to decrease in the degree of crystallinity and increase of available surface area. Pretreatment with ionic liquids facilitates separation of lignin and hemicellulose from cellulose which dissolves and acquires amorphous structure. The resulting substrate has high available surface area, but it loses quality upon drying. Determination of the degree of crystallinity by X-ray diffraction and the available surface area and pore size by the adsorption method using an indicator of the effectiveness of the pretreatment is conducted. The use of gas adsorption methods requires drying the samples, which negates the results of many kinds of preprocessing. The use of liquid-phase adsorption methods based on the comparison of the concentration of substances in the feed solution, and after equilibrium with the surface of the substrate are established, can more accurately determine the available surface area and pores size. Application of liquid phase method does not require any preparation of samples prior to analysis, in contrast to the gas adsorption method. When comparing the results of analysis by gas adsorption BET of liquid phase adsorption of glucose on the surface of the samples of the lignocellulosic raw material it has been found that after ionic liquids pretreatment available surface area has increased by 300-400 %, and the pore volume increased by 450-1700 %.
Comparison between Gas-adsorption Method and Liquid Phase-adsorption Method for the Surface Area Determination of Powders.
