Cellulosic films obtained from the treatment of sugarcane bagasse fibers with N -methylmorpholine- N -oxide (NMMO)

Ethanol/water organosolv pulping was used to obtain sugarcane bagasse pulp that was bleached with sodium chlorite. This bleached pulp was used to obtain cellulosic films that were further evaluated by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). A good film formation was observed when temperature of 74 °C and baths of distilled water were used, which after FTIR, TGA, and SEM analysis indicated no significant difference between the reaction times. The results showed this to be an interesting and promising process, combining the prerequisites for a more efficient utilization of agro-industrial residues.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), (CNPq), and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brazil; Fundação para a Ciência e a Tecnologia (FCT) and CEMU

Influence of production variables and starting material on charcoal stable isotopic and molecular characteristics

We present a systematic study on the effect of starting species, gas composition, temperature, particle size and duration of heating upon the molecular and stable isotope composition of high density (mangrove) and low density (pine) wood. In both pine and mangrove, charcoal was depleted in o13C relative to the starting wood by up to 1.6% and 0.8%, respectively. This is attributed predominantly to the progressive loss of isotopically heavier polysaccharides, and kinetic effects of aromatization during heating. However, the pattern of o13C change was dependant upon both starting species and atmosphere, with different structural changes associated with charcoal production from each wood type elucidated by Solid-State o13C Nuclear Magnetic Resonance Spectroscopy. These are particularly evident at lower temperatures, where variation in the oxygen content of the production atmosphere results in differences in the thermal degradation of cellulose and lignin. It is concluded that production of charcoal from separate species in identical conditions, or from a single sample exposed to different production variables, can result in significantly different o13C of the resulting material, relative to the initial wood. These results have implications for the use of charcoal isotope composition to infer past environmental change

An alternative application to the portuguese agro-industrial residue : wheat straw

The effects of alkaline treatments of the wheat straw with sodium hydroxide were investigated. The optimal condition for extraction of hemicelluloses was found to be with 0.50 mol/l sodium hydroxide at 55 °C for 2 h. This resulted in the release of 17.3% of hemicellulose (% dry starting material), corresponding to the dissolution of 49.3% of the original hemicellulose. The yields were determined by gravimetric analysis and expressed as a proportion of the starting material. Chemical composition and physico-chemical properties of the samples of hemicelluloses were elucidated by a combination of sugar analyses, Fourier transform infrared (FTIR), and thermal analysis. The results showed that the treatments were very effective on the extraction of hemicelluloses from wheat straw and that the extraction intensity (expressed in terms of alkali concentration) had a great influence on the yield and chemical features of the hemicelluloses. The FTIR analysis revealed typical signal pattern for the hemicellulosic fraction in the 1,200–1,000 cm−1 region. Bands between 1,166 and 1,000 cm−1 are typical of xylans.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo a Pesquisa do Estado de São Paulo/Brazil (FAPESP)Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BPD/26156/2005, SFRH/BPD/26108/200

Hydrogen peroxide bleaching of cellulose pulps obtained from brewer’s spent grain

Brewer’s spent grain (BSG) was evaluated for bleached pulp production. Two cellulose pulps with different chemical compositionswere produced by soda pulping: one from the original raw material and the other from material pretreated by dilute acid. Both of them were bleached by a totally chlorine-free sequence performed in three stages, using 5% hydrogen peroxide in the two initial, and a 0.25 NNaOHsolution in the last one. Chemical composition, kappa number, viscosity, brightness and yield of bleached and unbleached pulps were evaluated. The high hemicellulose (28.4% w/w) and extractives (5.8% w/w) contents in original BSG affected the pulping and bleaching processes.However, soda pulping of acid pretreated BSG gave a celluloserich pulp (90.4% w/w) with low hemicellulose and extractives contents (7.9% w/w and <3.4% w/w, respectively), which was easily bleached achieving a kappa number of 11.21, viscosity of 3.12 cp, brightness of 71.3%, cellulose content of 95.7% w/w, and residual lignin of 3.4% w/w. Alkaline and oxidative delignification of acid pretreated BSG was found as an attractive approach for producing high-purity, chlorine-free cellulose pulp.FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo), Brazil.CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico).Capes (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior)