Comparative potentiality of Kans grass (Saccharum spontaneum) and Giant reed (Arundo donax) as lignocellulosic feedstocks for the release of monomeric sugars by microwave/chemical pretreatment

Two-stage microwave (microwave/NaOH pretreatment followed by microwave/H₂SO₄ pretreatment) was used to release monomeric sugars from Kans grass (Saccharum spontaneum) and Giant reed (Arundo donax). The optimum pretreatment conditions were investigated, and the maximum monomeric sugar yields were compared. The microwave-assisted NaOH and H₂SO₄ pretreatments with a 15:1 liquid-to-solid ratio were studied by varying the chemical concentration, reaction temperature, and reaction time to optimize the amount of monomeric sugars. The maximum amounts of monomeric sugars released from microwave-assisted NaOH pretreatment were 6.8 g/100 g of biomass [at 80 °C/5 min, 5 % (w/v) NaOH for S. spontaneum and at 120 °C/5 min, 5 % (w/v) NaOH for A. donax]. Furthermore, the maximum amounts of monomeric sugars released from microwave-assisted H₂SO₄ pretreatment of S. spontaneum and A. donax were 33.8 [at 200 °C/10 min, 0.5 % (w/v) H₂SO₄] and 31.9 [at 180 °C/30 min, 0.5 % (w/v) H₂SO₄] g/100 g of biomass, respectively. The structural changes of S. spontaneum and A. donax were characterized using Fourier transform infrared spectroscopy and scanning electron microscopy.