Arundo donax L. was submitted to a process of isothermal autohydrolysis in the temperature range of 150-195°C, for periods between 0 and 15 h and a liquid/solid ratio ) 8 g g -1 , for the purpose of hydrolyzing the hemicelluloses to oligomers (compounds which are of interest to the food industry) and monomers. A conventional kinetic model was developed that explains the evolution over time of the hemicelluloses and hemicellulose degradation products. Kinetic modeling was also carried out using the severity factor approach and the kinetic parameters obtained in these two ways have been compared.
This paper will consider the influence of the autohydrolysis pretreatment on Paulownia fortunei L. woods to obtain a liquid phase (which can be used as a commercial source of organic reagents) and also a solid phase (which is valuable as raw material for pulping processes). Moreover, the influence of the operating conditionss viz., ethanol concentration (20%-60%), temperature (150-180 °C), and pulping time (30-90 min)son the organosolv pulping (the initial liquor-to-solid ratio was 8:1, with 10% of soda and 0.5% of anthraquinone) of the obtained Paulownia fortunei L. solid after the autohydrolysis process has been considered to determine the best pulping conditions and characteristics of the solid phase. In that form, the yield, kappa number, glucan and lignin contents, and tensile index values of the resulting pulps and paper sheets have been studied. The optimum of solubilized components has been obtained at 190 °C (0.92 g/L glucose, 1.61 g/L xylose, 0.60 g/L arabinose, 0.93 g/L acetic acid, 0.047 g/L 5-hydroxymethylfurfural, 0.141 g/L furfural, and 14.66 g/L oligomers). Under these conditions, a suitable chemical composition of pulps and acceptable yield (38%), kappa number (45), and tensile index (28.87 N m/g) could be obtained through operation at high temperature (180 °C), short pulping time (30 min), and low ethanol concentration (20%).
Samples of Arundo donax were subjected to isothermal autohydrolysis, defined by temperature, 150-195 degrees C; time, 0-15 h; and liquor to solid ratio, 8 g/g. The effect of the operational variables on the yield and composition of both liquid and solid phases obtained after the treatments has been studied. The oligomer concentration and composition have been determined. In the conditions leading to maximum oligomers concentration (defined by dimensionlees time theta=1) it can be produced up to 17.7 g oligomers/100 g raw material and four acetyl groups/10 xylose monomers. These oligomers are the mean of 50% of nonvolatile compounds. In these conditions, cellulose is almost quantitatively retained in the solid phase, whereas lignin is solubilized at 9%.
This paper will consider the influence of hydrothermal pretreatment to obtain a valuable liquid phase and
suitable raw material for pulping from Arundo donax L. and the influence of the operating conditions used
in the organosolv pulping of the Arundo donax L. autohydrolysis process (viz., ethanol concentration,
temperature, and pulping time) on the yield, kappa index, viscosity, and glucan content of the resulting pulp
to determine the best pulping conditions. From autohydrolysis, a valuable liquid phase could be obtained.
Maximum glucose and xylose contents have been obtained at 180 °C. Suitable characteristics of pulps and
acceptable yield, viscosity, and kappa index values could be obtained by operating at high temperature (200
°C), pulping time (130 min), and ethanol concentration (60%). The yields and kappa index values found for
pulps from solid residues of Arundo donax L. autohydrolysis were similar to those found for other Arundo
donax L. pulps.
A neural fuzzy system was used to investigate the influence of environmental variables (time, aeration, moisture, and particle size) on composting parameters (pH, organic matter [OM], nitrogen [N], ammonium nitrogen [NH 4 ϩ -N] and nitrate nitrogen [NO 3 Ϫ -N]). This was to determine the best composting conditions to ensure the maximum quality on the composts obtained with the minimum ammonium losses. A central composite experimental design was used to obtain the neural fuzzy model for each dependent variable. These models, consisting of the four independent process variables, were found to accurately describe the composting process (the differences between the experimental values and those estimated by using the equations never exceeded 5-10% of the former). Results of the modeling showed that creating a product with acceptable chemical properties (pH, NH 4 ϩ -N and NO 3 Ϫ -N) entails operating at medium moisture content (55%) and medium to high particle size (3-5 cm). Moderate to low aeration (0.2 L air/min ⅐ kg) would be the best compromise to compost this residue because of the scant statistical influence of this independent variable.
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