Pretreatment and Enzymatic Saccharification of Water Hyacinth, Sugarcane Bagasse, Maize Straw, and Green Coconut Shell Using an Organosolv Method with Glycerol and FeCl3

A method to pretreatment of biomasses using glycerol as a green solvent was developed. Optimization of organosolv pretreatment was performed using a 23 factorial design, investigating synergism among the variables particle size (from < 0.85 to > 2.0 mm), FeCl3 concentration (0.025-0.175 mol L-1), and temperature (160-220 °C). Although the effects of the variables differed according to the type of lignocellulose, it was nonetheless possible to find an optimal condition in common (< 0.85 mm; 0.025 mol L-1; 220 °C), which was economically and environmentally sustainable, employing a small amount of catalyst. The biomasses pretreated using this combination of factors exhibited enzymatic digestibility exceeding 93% after 48 h, reflecting efficient reduction of recalcitrance as a result of high removal of hemicellulose (ca. 90%), provided by the use of FeCl3, together with substantial delignification. There was low formation of inhibitors in the hydrolysate, indicating that it could be directly fermented. The lignin removed to liquors could be easily recovered by centrifugation. Tests carried out under the optimal condition revealed that after the pretreatment the biomass could be directly used in enzymatic hydrolysis, without washing and wet. Furthermore, after simple treatment, crude glycerol was as effective as commercial glycerol.

本研究开发了一种以甘油作为绿色溶剂的生物质预处理方法。本研究采用2³因子设计对有机溶剂预处理（organosolv pretreatment）工艺进行优化，考察了粒径（范围为<0.85 mm至>2.0 mm）、氯化铁（FeCl₃）浓度（0.025~0.175 mol·L⁻¹）与温度（160~220 ℃）三个变量间的协同效应。尽管各变量的影响因木质纤维素原料类型不同而存在差异，但仍可找到通用最优预处理条件：粒径<0.85 mm、氯化铁浓度0.025 mol·L⁻¹、温度220 ℃。该条件使用少量催化剂，兼具经济可行性与环境可持续性。采用该最优条件预处理的生物质，在48小时后酶解转化率超过93%。这一结果反映出，依托氯化铁的作用实现了约90%的半纤维素高效脱除，同时伴随显著的脱木质素效果，从而有效降低了生物质的抗降解性。水解液中抑制剂生成量极低，表明该水解液可直接用于发酵过程。脱除的木质素溶解于预处理液中，可通过离心法轻松回收。在最优条件下开展的验证实验表明，预处理后的生物质无需洗涤，可直接以湿态进行酶解反应。此外，经简单处理后的粗甘油，其预处理效果与商用甘油相当。