Fig. 3

SEM images (×1000 magnification) of sweet sorghum straw. a Untreated. b–d NaOH, H₂SO₄ and H₂O₂ pretreated, respectively. e Untreated and enzyme hydrolyzed. f–h NaOH, H₂SO₄ and H₂O₂ pretreated and enzyme hydrolyzed, respectively. Scale bars: 100 µm