Ftir spectra spectroscopy

The samples were straw treated with alkaline black liquor with 0, 1, 2, 3, 4, 5, and 6 cycles. The control was untreated corn stover. A total of 10 mg samples and 200 mg KBr were accurately weighed and placed in a mortar, fully ground, so that the particles were uniform and dispersed. Then, the samples were loaded into the tablet pressing mold and pressed with oil press at 20 MPa pressure for 2 min. The tablets were placed on a sample rack for FTIR spectra spectroscopy (Agilent, Palo Alto, CA, USA), and the spectra were recorded between 4000 and 400 cm⁻¹ [11 (link)]. The PerkinElmer Spectrum (PERKINELMER, Waltham, MA, USA) and Origin software (OriginLab, Northampton, MA, USA) were used for data analysis.

The samples were placed in an oven at 50 °C for 24 h to remove moisture. Then, a 10 mg dry sample was mixed with 200 mg KBr, manually ground in an agate mortar, and pressed at 20 MPa for 2 min in oil pressure. The tablets were placed on a sample rack for FTIR spectra spectroscopy (Agilent, Palo Alto, CA, USA), and the spectra were recorded between 4000 and 400 cm⁻¹. The PerkinElmer Spectrum (PERKINELMER, Waltham, MA, USA) and Origin software (OriginLab, Northampton, MA, USA) were used for data analysis.