Varga Eniko, Szengyel Zsolt, Réczey Kati
Department of Agricultural Chemical Technology, Budapest University of Technology and Economics, Hungary.
Appl Biochem Biotechnol. 2002 Spring;98-100:73-87. doi: 10.1385/abab:98-100:1-9:73.
Corn stover, the most abundant agricultural residue in Hungary, is a potential raw material for the production of fuel ethanol as a result of its high content of carbohydrates, but a pretreatment is required for its efficient hydrolysis. In this article, we describe the results using various chemicals such as dilute H2SO4, HCl, and NaOH separately as well as consecutively under relative mild conditions (120 degrees C, 1 h). Pretreatment with 5% H2SO4 or 5% HCl solubilized 85% of the hemicellulose fraction, but the enzymatic conversion of pretreated materials increased only two times compared to the untreated corn stover. Applying acidic pretreatment following a 1-d soaking in base achieved enzymatic conversion that was nearly the theoretical maximum (95.7%). Pretreatment with 10% NaOH decreased the lignin fraction >95%, increased the enzymatic conversion more than four times, and gave a 79.4% enzymatic conversion. However, by increasing the reaction time, the enzymatic degradability could also be increased significantly, using a less concentrated base. When the time of pretreatment was increased three times (0.5% NaOH at 120 degrees C), the amount of total released sugars was 47.9 g from 100 g (dry matter) of untreated corn stover.
玉米秸秆是匈牙利产量最为丰富的农业残余物，因其碳水化合物含量高，是生产燃料乙醇的潜在原料，但要实现其高效水解则需要进行预处理。在本文中，我们描述了分别以及连续使用各种化学物质（如稀硫酸、盐酸和氢氧化钠）在相对温和的条件下（120摄氏度，1小时）的处理结果。用5%的硫酸或5%的盐酸进行预处理可溶解85%的半纤维素部分，但预处理材料的酶促转化率相比未处理的玉米秸秆仅提高了两倍。在碱液中浸泡1天后再进行酸性预处理，可实现接近理论最大值（95.7%）的酶促转化率。用10%的氢氧化钠进行预处理可使木质素部分减少>95%，酶促转化率提高四倍多，酶促转化率达到79.4%。然而，通过延长反应时间，使用浓度较低的碱也可显著提高酶促降解性。当预处理时间延长三倍（120摄氏度下用0.5%的氢氧化钠）时，100克（干物质）未处理的玉米秸秆释放的总糖量为47.9克。
