Hidrólise ácida e enzimática de casca de arroz usando tecnologias alternativas

Abstract

Rice husk is a fairly abundant agro-industrial waste in the state of Rio Grande do Sul, hence the same has been suggested and studied to be used as in lignocellulosic hydrolysis to produce fermentable sugars material. However, processes of hydrolysis in most cases are more expensive and impractical. In this context, this work aimed to study which evaluated acid and enzymatic hydrolysis of rice hulls to obtain fermentable sugars using some alternative technologies such as ultrasound and supercritical CO2 to increase the yields of sugars. In the acid hydrolysis, the yields obtained at optimized conditions were 113.0 and 162.0 g.kg-1 for conventional and ultrasound-assisted hydrolysis, where the yield obtained by ultrasound-assisted hydrolysis was around 43% higher than for the conventional hydrolysis. In the enzymatic hydrolysis, it was evaluated the use of supercritical CO2 as co-solvent and ultrasound-assisted hydrolysis and the results were compared with conventional procedure. Maximum yield of fermentable sugar obtained was about 16 g.kg-1using conventional or ultrasound-assisted hydrolyses. The yield obtained in the hydrolysis using supercritical CO2 as co-solvent was around 4.2 g.kg-1. Enzymatic hydrolysis using conventional procedure showed to be the best alternative to obtain fermentable sugar from rice hulls since the innovative technologies employed did not lead to better results. For acid hydrolysis, it was possible to obtain high yield using less acid and low temperature, in a manner that ultrasound can be used as a device for process intensification.