Figure 4.

Fourier transform infrared (FTIR) spectra of sugarcane bagasse (SB). (a) FTIR spectra of the crushed SB in the range of 4,000 to 1,000 cm^-1. The black line represents the SB. The red line, blue line, and green line represent the hydrolysis with sulfuric acid (H₂SO₄), alkaline hydrolysis with sodium hydroxide (NaOH), and enzymatic hydrolysis, respectively. (b) FTIR spectra of the crushed SB in the range of 1,300 to 750 cm^-1. The black line represents the SB. The red line, blue line, and green line represent the hydrolysis with sulfuric acid (H₂SO₄), alkaline hydrolysis with sodium hydroxide (NaOH), and enzymatic hydrolysis, respectively. The vertical dashed line denotes the wave number related to SB, which provides a better comparison. (c) FTIR spectra of the crushed SB in the range of 1,800 to 1,400 cm^-1. The black line represents the SB. The red and blue line represent the acid hydrolysis with sulfuric acid (H₂SO₄) and alkaline hydrolysis with sodium hydroxide (NaOH), respectively. The vertical dashed line denotes the wave number related to SB, which provides a better comparison. (d) FTIR spectra of the SB in the range of 3,900 to 2,700 cm^-1. The black line represents the SB. The red line, blue line, and green line are the acid hydrolysis with sulfuric acid (H₂SO₄), alkaline hydrolysis with sodium hydroxide (NaOH), and enzymatic hydrolysis, respectively. The vertical dashed line denotes the wave number related to SB, which provides a better comparison. FTIR, Fourier transform infrared; SB, sugarcane bagasse.