Resumo

CORDOBA, Jhon Alexander et al. Caracterización y valoración química del olote: degradación hidrotérmica bajo condiciones subcríticas. Rev. latinoam. quím [online]. 2013, vol.41, n.3, pp.171-184. ISSN 0370-5943.

Corn cob was characterized chemically and hydrothermally treated under subcritical conditions to modify their recalcitrance and render a solid fraction of cellulose and lignin and a soluble fraction rich in xylose. The chemical characterization of carbohydrates was carried out by HPLC, while lignin and xylan were characterized by means of FTIR-ATR and ¹³C-NMR. The hydrothermal treatment was performed in bullet-type reactors heated in a muffle furnace at 160, 230 and 300°C at times of 30, 45 and 60 min, with hydromodules of 1.7, 2.0 and 2.5 w/v. The yield was determined from the insoluble fraction of the corn cob and the concentration of carboxylic groups was measured in the soluble fraction. The results indicated that corn cob contained 45% of cellulose, 15.8% lignin (p-hydroxyphenyl, guaiacyl and syringyl units) and 33.6% hemicelluloses. Temperature and time of reaction showed significant effects on yield and generation of carboxylic groups. It was possible to convert up to 43% of the corn cob to hemicelluloses and lignin compounds soluble in aqueous medium, under hydrothermal treatment at subcritical conditions, while increasing the concentration of carboxylic groups in the soluble fraction to 29.3 meq/100 g of corn cob.

Palavras-chave : Biomass; recalcitrance; carboxylic groups; hemicellulose; cellulose; lignin.