PRESSURIZED WATER PRETREATMENT TO INCREASE SUGAR PRODUCTION FROM GREEN COCONUT

Resumo

Pretreatment of lignocellulosic industrial waste is necessary to promote the cellulose accessibility. Thus, this study evaluated the production of green coconut sugars during pressurized hydrothermal pre-treatment and enzymatic hydrolysis of the pretreated biomass. Pretreatment of the green coconut shell was carried out at 70 °C, 150 bar and water flow rate of 1 mL/min for 4 h. Samples from the system output stream were analyzed by HPLC and Folin Ciocalteu method. The solid fraction was characterized (chemical composition, XRD and FTIR) and subjected to enzymatic hydrolysis. The liquid fractions of pretreatment provided a defined profile of released glucose, xylose, phenolic components and acetic acid over time. After 40 min, most of fermentable sugars were released, forming a liquor with a sugar content above 10 g/L. Post-treated biomass showed a reduction of cellulose (26 % to 17 %) and hemicellulose (23 % to 18 %) and an increase in lignin content (32 % to 44 %). Despite this new chemical composition of the biomass, the pretreated material had lower crystallinity indexes and modifications in its chemical groups. This favored cellulosic conversion from 15 % to 55 %, producing 63.5 % more glucose than the untreated green coconut shell during enzymatic hydrolysis. Thus, the pressurized pre-treatment favored the fermentable sugar production from the green coconut shell, and there is also the possibility of utilizing the sugars present in the pre-treatment liquor.