Effects of ammonium carbonate pretreatment on the enzymatic digestibility and structural features of rice straw

Rice straw was pretreated with ammonium carbonate ((NH4)2CO3), a major intermediate of ammonia-based carbon capture process, and evaluated for the effects of critical pretreatment parameters including (NH4)2CO3 concentration (5–25%), temperature (60–90 °C), and reaction time (4–24 h) on enzymatic digestibility. Pretreatment of rice straw at 80 °C for 12 h using 20% (NH4)2CO3 and 1:10 solid to liquid ratio resulted in enzymatic digestibility of 72.2%, which was higher than that pretreated with the same moles of aqueous ammonia. We also investigated physical characteristics of pretreated rice straw, including surface area, pore volume and size, crystallinity, and scanning electron microscopy image. The ammonium carbonate pretreatment process, as a novel pretreatment technique, enhanced enzymatic hydrolysis of lignocellulose by altering structural features.