FEATURES OF THE PRETREATMENT OF WHEAT STRAW FOR HYDROLYSIS

One of the stages of the complex processing of plant raw materials is the separation of lignin and hemicellulose from the lignocellulosic complex, followed by obtaining valuable chemical products or fuel from it. This stage is an integral part of the pretreatment of raw materials for hydrolysis. But this stage is the most energy-consuming of the fuel ethanol obtaining, and aims to destroy the stable structure of cellulosic biomass and make cellulose more accessible to enzymes that convert carbohydrate polymers into fermentable sugars. High energy costs of pretreatment of raw materials for hydrolysis are because this process takes place at high temperatures and pressure. The work aimed to compare the effect of temperature, alkali concentration, and treatment duration of alkaline solutions of wheat straw by two methods of alkaline pretreatment on the process of lignin removal during preparing of raw materials for hydrolysis. It was determined that increasing the alkali concentration from 0.5 to 4% reduces the lignin content in the sample to 4.17% of the total amount of solids for autoclaving at 90 ºС, at 121 ºС the amount of lignin content decreases to 2.98%. Processing at a temperature of 90 ºС reduces the lignin content to 3.15%. The processing duration of affected the process of pretreatment as follows. The minimum lignin content in the sample for autoclaving at 90 ºС for 60 min of treatment was 4.12% of the initial one. The minimum lignin content in the sample at 121 ºС was observed for one hour and made up 3.15%. Processing in a rotor-pulsation apparatus leads to a lignin content in the sample of up to 2.98% in 120 minutes. The lignin is the most effectively removed in the temperature range of 80-121ºС. The minimum lignin content in the sample for autoclaving was 2.98% at 121 ºС. For processing, the maximum value of removed lignin was 3.15% at 90 ºС.