Improvement of potassium permanganate pretreatment by enzymatic saccharification of rice straw for production of biofuels

Commonly, the agricultural waste, i.e. lignocellulosic biomass is disposed through combustion causing air pollution with production of PM2.5 and PM10 particles. However, it has been found that these biomasses can be used as source for the production of biofuels and other valuable biochemicals. Though deconstruction of lignocellulosic biomass is challenging due to its complex structure. In this study, rice straw (RS) was pretreated using potassium permanganate (KMnO4) to enhance the enzymatic saccharification efficiency. The study was carried out by varying the operational factors in pretreatment, including temperature (30-90°C), time (30-360 min) and concentration of KMnO4 (0.5-3.0, % w/v), respectively, based on Box-Behnken design (BBD). Through multi-regression analysis of the experimental data obtained after pretreatment, the optimum conditions were determined. The optimum conditions for temperature, time and potassium permanganate concentration were 48.09°C, 360 min, and 1.36% w/v, respectively. The saccharifications of pretreatment and untreated rice straw were carried out using Cellic Ctec2. The reducing sugar was determined by using DNS method and the yields of the untreated and pretreated RS were 32.38 and 49.011 mg/mL, respectively. The results showed that the sugar for pretreated RS were 1.51 fold times higher compared to untreated RS. Therefore, this work illustrates the pretreatment efficiency for KMnO4 to enhance the reducing sugar yield during saccharification, which can be used for biofuel and value-added product productions.