Avaliação do pré-tratamento acalino na hidrólise enzimática dos resíduos da palha de carnaúba
The carnauba (Copernicia prunifera) is a typical Brazilian northeast palm tree whose main economic activity is the extraction of wax. This activity presents a great generation of residue rich in cellulose, in which it has potential for the production of Second Generation Ethanol. However, due to the...
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| Formato: | bachelorThesis |
| Idioma: | pt_BR |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/38837 |
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| Resumo: | The carnauba (Copernicia prunifera) is a typical Brazilian northeast palm tree whose main economic activity is the extraction of wax. This activity presents a great generation of residue rich in cellulose, in which it has potential for the production of Second Generation Ethanol. However, due to the high lignin and hemicellulose load associated with cellulose in a complex structure, the enzymatic attack it’s difficult, and an adequate pre-treatment of this material is necessary. The use of bases in the pretreatment of lignocellulosic materials leads to its swelling, increasing its internal surface and reducing the crystallinity of the cellulose, and the rupture of the bonds between cellulose and lignin. The objective of this study was to optimize the enzymatic hydrolysis of the carnauba straw residue, focusing on the biomass pretreatment, applying NaOH solutions at concentrations of 1% (w/v) (PA1), 2% (w/v) (PA2), 3% (w/v) (PA3) and 4% (w/v) (PA4). The chemical compositions of the carnauba strains in natura and pretreated were evaluated according to NREL, as well as the DRX and FTIR analyzes. The in natura and pre-treated residues were subjected to enzymatic hydrolysis for a period of 96 hours. The results of the chemical characterization of the materials in studies indicated that the pre-treatments applied were able to remove a significant amount of lignin and hemicellulose, which can improve the accessibility of the enzymes favoring a greater cellulose conversion. In relation to the DRX analysis, an increase in the crystallinity index (CI) of 41.89% for the in natura residue was observed for 48.93%, 50.75%, 53.97% and 55.15% for, respectively, residues pretreated with NaOH 1%, 2%, 3% and 4%. This behavior may be associated to the removal of hemicellulose and amorphous lignin associated with cellulose, improving the accessibility of these polysaccharides to the enzymes. After the enzymatic hydrolysis, pre-treatments with NaOH concentration equal to or above 2% (w/v) favored an improvement in the cellulosic conversion of the residues. In spite of a slightly lower performance of the residue that presented higher conversion of cellulose (the pretreated PA4 residue), pre-treated material PA2 stood out as an alternative to reduce costs in the production of cellulosic ethanol. In this way, it becomes possible to halve the mass of sodium hydroxide and the amount of washes of the material after pretreatment. |
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