Ozonólise da biomassa lignocelulósica (bagaço de cana) visando a redução do teor de lignina e do ácido p-Cumárico. 2013

Abstract

This research aimed to reduce lignin and p-coumaric acid content through ozonolysis using sugarcane bagasse to obtain a material with lower recalcitrance. Ozone was produced by an ozone generator with medical purity oxygen. The reaction occurred in a glass column with continuous ozone flow at 400 mg / h. The standardization of the ozone flow was performed by iodometry. As a sample, it was used sugarcane bagasse (Saccharum spp), variety rb867515 pre-extracted with ethanol PA. The bagasse was previously ground, and lignin and p-coumaric acid determined by the Klason method (24%) and HPLC (96 mg / ml), respectively. Infrared (FTIR) transmittance mode analyses of control sample, and the reaction products under neutral, basic and acidic pH revealed that the reactions promoted biomass transformations related to structural characteristics of the original lignin content. The observed infrared signals were quantitated by baseline correction using the signal 1500 cm-1 as internal standard. Spectra were recorded 13C NMR CP / MAS solid samples as well as control of the ozonolysis products. For the analysis of p-coumaric acid content, it was used a method for the determination of phenolic acids in the cell wall described in specific literature. The determination of p-coumaric acid was performed by HPLC using standard from FLUKA, inc. to obtain calibration curve. It was found 96.μg/ml on control sample, whereas in neutral condition 6h was found 4.9 mg / ml, in basic 2h was found 7.5 mg / ml and in 4h acid was found 9.5 g / ml. There was a significant loss of lignin, as determined by the Klason method, reducing the original 24% lignin of the control sample to 7.55% (2 h), 8.72% (4 h) and 13.78% (6 h) under neutral conditions, 11.70% (2 h), 13.83% (4 h) and 9:35% (6 h) and 6.67% (2 h) 6.67% (4 h) and 13.04% (6 h) in acidic pH. These results showed that the process of ozonolysis reduced the lignin content and p-coumaric acid concentration in the biomass allowing the change of the proposed structural characteristic of lignin etheric structure for a condensed structure, indicating that the original recalcitrance was significantly reduced the observed characteristics final material. There were some losses of cellulose and hemicellulose. The analyzes showed no changes in these constituents.