Pretreatment of quinoa straw with 1-butyl-3-methylimidazolium chloride and physiochemical characterization of biomass

Abstract Quinoa straw was pretreated with 1-butyl-3-methylimidazolium chloride ([Bmim]Cl). The levels of pretreatment temperature, duration, and liquid/solid ratio were optimized using orthogonal design to enhance the reducing sugar yield of treated sample. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction were used to assess structural changes in native and pretreated biomass. The effect of [Bmim]Cl pretreatment on the structure and properties of quinoa straw was significant. The optimum pretreatment conditions were liquid/solid ratio of 15:1, temperature of 100 °C, and duration of 5 h. The maximum reducing sugar yield of 33.22% was obtained, which was significantly higher than that of native quinoa straw. Unlike the untreated one, the pretreated quinoa straw showed clear pores and cracks and incomplete structure. Significant differences in the reducing sugar yield and structural characterization between [Bmim]Cl pretreated and untreated biomass demonstrated that [Bmim]Cl pretreatment of quinoa straw was effective for enzymatic hydrolysis.