玉米芯残渣的碱性亚硫酸盐预处理及其反应动力学模型

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pH、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。

Alkaline sulfite pretreatment of corncob residue and its reaction kinetic model

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 liquors 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℃, 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 hydrolysiscellulase loading of 5 FPU·(g glucan)^-1], and the yield of lignosulfonate in pretreatment spent liquors was 31.5 g·(100 g CCR)^-1 under the same pretreatment condition. Lignin factor (LF) was proposed to predict lignin content of 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. And reasonable predictions of SED were obtained to within approximately 10% of the experimental data.