【摘要】玉米芯提取木糖后残留了大量富含纤维素和木质素的废弃物。针对玉米芯残渣 (corncob residues, CCR) 中木质素含量高和半纤维素含量很低的特点, 采用碱性亚硫酸盐法进行预处理。研究了预处理p H、液固比、温度、亚硫酸盐用量等条件对纤维素保留率、木质素去除率、底物酶解效率以及预处理液中木质素磺酸钠含量的影响规律。结果表明, 当亚硫酸钠用量为10% (质量) 、氢氧化钠为5% (质量) 、液固比为6:1、160℃预处理1 h时, 可去除86.1%的木质素、保留82.4%的纤维素, 底物的72 h酶解率达85.1%[酶载量为5 FPU· (g葡聚糖) -1], 预处理液中木质素磺酸钠的收率为31.5 g· (100 g CCR) -1。为了指导放大试验和工程应用, 提出了一个能准确预测底物木质素含量的参数——木质素因子 (lignin factor, LF) , 在此基础上成功建立了脱木质素反应动力学经验公式以及底物酶解效率的预测方程, 预测值与实测值误差在10%之内。
【基金资助】 国家自然科学基金项目 (21676109, 21376100) ; 广州市科技计划项目 (201707020025) ; 广东省特支计划 (2016TX03Z298) ; 广东省国际合作项目 (2013B051000011) ;
Alkaline sulfite pretreatment of corncob residue and its reaction kinetic model
【Abstract】Corncob residues (CCR) were obtained from corncobs by using acid hydrolysis for extraction of xylose. Due to the high content of lignin and low content of hemicellulose in corncob residues, the alkaline sulfite pretreatment was used to treat the corncob residue. The effects of pH, liquid/solid ratio, temperature and the dosage of sodium sulfite on the cellulose retained, delignification, substrate enzymatic digestibility (SED) and yield of lignosulfonate in pretreatment spent liquor were investigated. The results showed that with 10% (mass) sodium sulfite (Na2SO3) and 5% (mass) sodium hydroxide (NaOH) on CCR and 1 h pretreatment at 160 °C, the alkaline sulfite pretreatment could make 86.1% of lignin removed and 82.4% of cellulose recovered in pretreatment liquid/solid ratio of 6/1. The SED of CCR increased from 46.4% to 85.1% after 72 h hydrolysis [cellulase loading of 5 FPU·(g glucan)−1], and the yield of lignosulfonate in pretreatment spent liquor was 31.5g·(100 g CCR)−1 under the same pretreatment condition. Lignin factor (LF) was proposed to predict the lignin content of the pretreated CCR to guide the scale up test and engineering application. The delignification kinetics and prediction equation for SED of CCR were established based on the experimental data. The error of SED predicted and SED measured was within 10%.
【Keywords】 biomass; alkaline sulfite pretreatment; mathematical modeling; prediction; reaction kinetics;
【Funds】 National Natural Science Foundation of China (21676109, 21376100); Science and Technology Program of Guangzhou, China (201707020025); Special Support Plan for Cultivating High-level Talents of Guangdong, China (2016TX03Z298); International Cooperation Program of Guangdong Province, China (2013B051000011);
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