Effects of a Pretreatment Combining Rubbing with Dilute Alkali on the Enzymatic Hydrolysis-Reducing Sugar Yield and Structure of Rice Straw

Abstract

Abstract. Current pretreatments to digest cellulose straw are characterized by high energy consumption, environmental pollution, and other problems that limit straw biomass utilization. In this work, a rice straw rubbing pretreatment that is less energy-intensive than existing pretreatments is proposed to partly destroy the silicon layer. The rubbing pretreatment did not significantly increase the enzymatic hydrolysis-reducing sugar production rate of rice straw, but it enhanced the effect of subsequent dilute alkali pretreatment. The enzymatic hydrolysis-reducing sugar production rate after combined rubbing and alkali pretreatment was 33.63%, which was significantly higher than the rates achieved with original straw and with dilute alkali pretreatment alone. Rubbing pretreatment removed 33.40% of the surface silicon from the straw. This was significantly higher than the removal rates for original straw and dilute alkali pretreatment alone, but there was no marked difference in removal rate between the rubbing pretreatment and the combined rubbing and alkali pretreatment. The results indicate that rubbing pretreatment is an effective way to promote the efficiency of alkali pretreatment, and combined rubbing and alkali pretreatment greatly enhances the efficient utilization of rice straw.Highlights33.40% of the silicon layer on the surface of rice straw was removed by the rubbing pretreatment.Cracks caused by the rubbing pretreatment are beneficial for chemical reagents to access the inner composites.The rubbing pretreatment could enhance the efficiency of follow-up treatments for rice straw. Keywords: Rice straw, Rubbing pretreatment, Silicon layer, Sugar yield, Structure.