Martínez-Cartas Mª Lourdes, Cuevas-Aranda Manuel, Sánchez Sebastián
Department of Chemical, Environmental and Materials Engineering, Higher Polytechnical School of University of Jaén, Avda. de la Universidad s/n, 23700 Linares, Spain.
University Institute of Research in Olive Grove and Olive Oils, University of Jaén, Science and Technology Park GEOLIT, 23620 Mengíbar, Spain.
Polymers (Basel). 2024 Dec 19;16(24):3548. doi: 10.3390/polym16243548.
A sequential valorization process of sunflower stalks was carried out using nitric acid (0.1-2 mol dm) as a hydrolytic agent and fermenting the hydrolysate of higher sugar concentration in the presence of the non-conventional yeast . Values reached for ethanol yield (0.25 g g) and xylitol yield (0.14 g g) were higher than those achieved after pretreatment with other acids in previous studies. The effect of acid treatment with nitric, phosphoric, and sulfuric acids on the separated solid fractions was evaluated to determine its potential use as solid biofuel by FTIR and SEM determinations. A significant loss of lignin and hemicellulose was found in the solid treated with nitric acid, while a higher HHV was obtained when pretreated with phosphoric acid (19.16 MJ kg) and sulfuric acid (19.12 MJ kg). A subsequent enzymatic hydrolysis of acid-pretreated solids showed that the nitric acid pretreatment increased the availability of glucose from the cellulose fraction to a greater extent than the other two acids, by reducing the hemicellulose fraction to 0.7% and the lignin fraction to 2.5%. This study shows that pretreatment of biomass with nitric acid leads to better fermentation results to obtain biofuels such as ethanol, which could be further increased by additional enzymatic hydrolysis, while pretreatment with the other two acids generates better solid fuels.
以硝酸（0.1 - 2 mol dm）作为水解剂，对向日葵秸秆进行了连续增值过程，并在非常规酵母存在的情况下对较高糖浓度的水解产物进行发酵。乙醇产量（0.25 g g）和木糖醇产量（0.14 g g）达到的值高于先前研究中用其他酸预处理后获得的值。通过傅里叶变换红外光谱（FTIR）和扫描电子显微镜（SEM）测定，评估了用硝酸、磷酸和硫酸进行酸处理对分离出的固体部分的影响，以确定其作为固体生物燃料的潜在用途。在用硝酸处理的固体中发现木质素和半纤维素有显著损失，而用磷酸（19.16 MJ kg）和硫酸（19.12 MJ kg）预处理时获得了更高的高位发热量（HHV）。对酸预处理后的固体进行后续酶水解表明，硝酸预处理比其他两种酸更大程度地提高了纤维素部分葡萄糖的可利用性，将半纤维素部分减少到0.7%，木质素部分减少到2.5%。这项研究表明，用硝酸对生物质进行预处理可获得更好的发酵结果以生产乙醇等生物燃料，通过额外的酶水解可进一步提高产量，而用其他两种酸预处理则可产生更好的固体燃料。
