COMPARISON OF TWO METHOD FOR ISOLATION OF FIBRILLATED CELLULOSE FROM LIGNOCELLULOSIC BIOMASS

Fibrillated cellulose from distillery refuse based on maize starch was prepared by two different procedures. The effect of sonification was evaluated atacid-alkali extractionas well as the type of used acid. The results from the alkali-acid procedure were compared with these obtained by method of steam explosion at different temperatures. The acid-alkali method brings a better result regarding degradation of hemicellulose and lignin as well as cellulose. Lignin/hemicellulose were only released from lignocellulose network using steam explosion at 120-180°C. At higher temperature, the results were comparable with those obtained by acid-alkali method. Similarly pore size distribution of filter paper decreased more significantly when fibrillated cellulose from acid-alkali treatment was applied. After steam explosion, higher extend of longer still fibres remains

Comparative study of wood color stability using accelerated weathering process and infrared spectroscopy

The objective of this study was to investigate effects of artificial weathering on color stability of six tropical wood species: Apuleia leiocarpa (Vog.) Macbride, Bagassa guianensis Aubl., Dipteryx odorata (Aubl.) Wild., Hymenea courbaril/Linn., Manilkara bidentata A. Chev., Tabebuia sp. Chemical composition of weathered wood was also studied by FT-IR spectra. With the progressive artificial weathering color of wood changed gradually. Hymenea courbaril Linn. wood occurred the greatest range of the total color change. The largest changes in intensity of the wood color took place at the beginning of artificial weathering process. FT-IR analysis indicated the occurrence of lignin and hemicellulose oxidative changes resulting in formation of carbonyl and carboxyl compounds during weathering. Oxidation products are the main cause of wood surface discoloration. Additionally, changes suggesting depolymerisation of cellulose were identified as well.

Development and validation of an analytical method for condensed tannin extracts obtained from the bark of four tree species using HPLC

Herein, we evaluated the content of condensed tannins present in the bark of four tree species that are Quercus laurina Humb. & Bonpl., Quercus crassifolia Humb. & Bonpl., Arbutus xalapensis Kunth, and Prunus serotina Ehrn. An analytical method using high-performance liquid chromatography (HPLC) for condensed tannin extracts was developed and validated. Also, the aqueous extracts were analyzed by Fourier transform infrared spectroscopy (FTIR). Based on the Stiasny number, A. xalapensis, and Q. laurina represent an important source of condensed tannins, which may be subject to exploitation. Using infrared spectroscopy, it was observed that tannins do not show an important signal of carbonyl groups (aromatic esters) with respect to high purity catechin. Furthermore, the band of the hydroxyl group is less pronounced in tannins, because various hydroxyl are interacting with each other. However, it can be seen that the method of extraction of wood tannins developed in this work, presents satisfactory results.