Decomposition Of Xylan Research Articles

Etude dilatométrique de la pyrolyse du xylane en régime non isotherme

The thermal decomposition of xylan in a nitrogen environement have been studied by dilatometry analysis. The data from this study are analysed in the light of previous conclusions obtained from thermogravimetric analysis of the same materials. The dimensional change measurements indicate that chemical structure of xylan was strongly altered by this process and the temperature phase transformations and the thermal stability of the studied samples become easily accessible.

Pyrolysis kinetics of lignocellulosic materials—three independent reactions model

The behaviour of biomass components (cellulose, xylan—representative of hemicelluloses—and lignin) was studied thermogravimetrically with linear temperature programming, under nitrogen and air. The results were compared and the pyrolysis kinetics of cellulose determined, assuming a first-order kinetic function. The thermal decomposition of xylan and lignin could not be modelled with acceptable errors by means of simple reactions. Thermograms were determined for pine and eucalyptus woods and pine bark, under inert (nitrogen) or oxidizing (air) atmosphere. The pyrolysis of these lignocellulosic materials was modelled with good approximation by three first-order independent reactions. One of these reactions is associated with the primary pyrolysis of cellulose, its parameters being previously determined and fixed in the model. The model parameters are the activation energies and pre-exponential factors for the pyrolysis of the remaining two pseudo-components and two additional parameters related to the biomass composition. A method to determine this composition was proposed. The results calculated in this way were compared with data from the literature and those determined thermogravimetrically in air, showing good agreement.

Kinetics of weight loss by thermal decomposition of xylan and lignin. Influence of experimental conditions

The kinetics of weight loss in the thermal decomposition of xylan and lignin in a nitrogen environment have been studied thermogravimetrically. The data from this study are analysed in the light of previous conclusions obtained with cellulose. The results from isothermal and dynamic experiments at different heating rates are related by using the results of dynamic experiments with low heating rates (1.5 °C min −1) as a reference.

海洋中のキシラン分解細菌に関する研究-I

Various xylan-decomposing microorganisms are known to be widely distributed in the tertestrial environment. A number of organisms and the microbial xylanases have been studied microbiologically or enzymatically by many investigators. However, very little is known on the xylan-decomposing organisms isolated from the marine materials. Therefore, it appears of interest to investigate systematically the xylan-decomposing bacteria and the bacterial xy-lanases in the marine environment. In the first instance of this series, the present investigation was undertaken to establish the optimum conditions for the isolation and enumeration of aerobic β-1, 4'-xylan-decomposing bacteria in the marine environment. From results obtained (Tables 1-9), it was concluded that the most suitable methods for the isolation and enumeration of the xylan-decomposing bacteria from the marine materials, were as follows: 1. The medium was recommended, which contained 10g of β-1, 4'-xylan, 5g of peptone, 1g of yeast extract, (0.1g of ferric phosphate), 10g of agar and 1000ml of filtered sea water, and had a pH of 7.5 after autoclave sterilization. 2. The pour plate method was useful. Namely, every material was diluted successively by powers of 10 with sterilized sea water, and the inoculum diluted appropriately was poured in to the medium, and the inoculated medium was incubated at 25°C for 5 days. Then, among the colonies developed on the plate, the colony surrounded by a halo which was indicative of decomposition of xylan, was enumerated and isolated.

Decomposition of Xylan by Sporocytophaga myxococcoides

THAT Sporocytophaga myxococcoides is unable to grow on xylan and xylose has been shown by several investigators1 ; for that reason the organism was used in an investigation to find if cellulase is able to decompose xylan. Fuller and Norman2 report a disappearance of xylan from corn stalk cellulose during growth of Sporocytophaga myxococcoides.