In this work, a two-step pretreatment using acid and alkali was optimized for rice rusks (Oryza sativa) using a 2⁵⁻¹ fractional factorial design (FFD), followed by a central composite design (CCD) to further optimization of enzymatic saccharification. The effect of five variables was simultaneously evaluated: H₂SO₄ concentration (from 0–5.4 % w/w); NaOH concentration (0–6 % w/w); temperature (85–125 °C); time (20–100 min) and solid to liquid ratio (S/L = 5–12.5 % w/w). The best pretreatment conditions were: 1.8 % w/w of H₂SO₄ in the first step and 6 % w/w of NaOH at 85 °C for 100 min at a S/L = 12.5 % (w/w) in the alkaline step, which resulted in 58.7 mg of glucose/g substrate, an 8-fold increase compared to the sample in natura (7 mg/g). In rice husks, in contrast to the results commonly found in literature, NaOH extracts mainly silica instead of lignin, while H₂SO₄ has an important role in lignin removal. High purity silica (97 %) was isolated at high yields (70 %) from the alkaline liquor by a simple and scalable process, which could contribute to making ethanol production from this biomass economically viable.

在这项工作中，使用酸和碱的两步预处理水稻面包干（优化的稻使用2）^5-1部分因子设计（FFD），随后是中心组合设计（CCD）对酶糖化的进一步优化. 同时评估了五个变量的影响：H ₂ SO ₄浓度（0–5.4 % w/w）；NaOH 浓度（0–6 % w/w）；温度 (85–125 °C); 时间（20–100 分钟）和固液比（S/L = 5–12.5 % w/w）。最佳预处理条件为：1.8 % w/w 的 H ₂ SO ₄在第一步和 6% w/w 的 NaOH 在 85 °C 下以 S/L = 12.5% (w/w) 在碱性步骤中保持 100 分钟，这导致 58.7 mg 葡萄糖/g 底物，8与自然中的样品相比增加 - 倍（7 毫克/克）。在稻壳中，与文献中常见的结果相反，NaOH 主要提取二氧化硅而不是木质素，而 H ₂ SO ₄在去除木质素方面具有重要作用。通过简单且可扩展的工艺从碱性溶液中以高产率 (70%) 分离出高纯度二氧化硅 (97%)，这有助于使这种生物质的乙醇生产在经济上可行。