Thermogravimetric analysis during the decomposition of cotton fabrics in an inert and air environment

Chemical Engineering Department, University of Alicante, P.O. Box 99, E-03080 Alicante, Spain
Journal of Analytical and Applied Pyrolysis (Impact Factor: 3.56). 06/2006; 76(1-2):124-131. DOI: 10.1016/j.jaap.2005.09.001
Source: OAI


The thermal degradation of samples of used cotton fabrics has been investigated using thermogravimetric analysis (TGA) between room temperature and 700 °C. Experiments were carried out with about 5 mg of sample in three different atmospheres: helium, 20% oxygen in helium and 10% oxygen in helium. Three different heating rates were used at each atmosphere condition. A kinetic model for the decomposition of used cotton fabrics explaining the behavior of all the runs performed has been proposed and tested. For the pyrolysis of the cotton, the model comprises two parallel reactions. For the combustion process, one competitive reaction was added to each parallel reaction of the pyrolysis model and four combustion reactions of the different solid fractions to obtain volatiles. One single set of parameters can explain all the experiments (pyrolysis, oxidative pyrolysis and combustion) at the three different heating rates used.

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Available from: Julia Moltó, Apr 07, 2014
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    • "Both samples exhibited a similar behavior. As the heating rate increased, there was a displacement of the TG curves to higher temperatures (Moltó et al., 2006). This thermal behavior provided information on the reliability of the thermogravimetric data for the application of the kinetic method "
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    ABSTRACT: Thermal conversion processes that use coffee husk are an alternative to solve the environmental problems of disposal and waste burning in open places and avoid greenhouse gases emissions in the atmosphere. The present study evaluates in natura coffee husk samples and residues obtained from a combustion process in a Drop Tube Furnace (DTF). Such an evaluation consists in understanding the efficiency of the burning process, therefore the activation energies (E a) of the combustion process for both samples were determined. The isoconventional kinetic method (Model Free Kinetics) was used for the determination of the E a values of the samples. The E a values of the main stages of the combustion process (devolatilization and carbonization) for both samples were compared. Thermogravimetric (TG) and Derivative Thermogravimetric (DTG) curves at five heating rates (10, 15, 20, 25 and 30 ºC min -1) were used for the determination of hemicellulose, cellulose and lignin. SEM images and EDS analysis were applied as complementary techniques in the combustion process. The results show that for both samples the E a values were higher for the carbonization step than for devolatilization. The E a values for the stages of devolatilization and carbonization for the residues were 33 and 15% lower than those for the in natura coffee husk samples. The lower E a values in both steps for the residues are indicative of a reduction in the complexity of the reaction mechanism, which can be a parameter for the evaluation of the biomass combustion process. According to the SEM images, the residues showed exploded surfaces caused by the combustion process, whereas in the in natura samples a denser and robust structure was observed. The ash formed after the combustion process in the thermobalance was also evaluated by SEM and EDS analyses and the results showed a more homogenous structure with tiny particles in comparison with the in natura coffee husk samples. The EDS analysis confirmed the presence of precursor elements in the samples, such as potassium and other inorganic materials, which were intensified after the combustion process.
    15th Brazilian Congress of Thermal Sciences and Engineering, Belém (PA); 11/2014
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    • "Few studies have examined simultaneously the thermal degradation of these materials in inert and oxidizing atmosphere. These works have highlighted the influence of oxygen on the mass loss [9], the gaseous products [9] [10] [11] and the kinetics [10] [11] [12] [13] [14] [15] [16]. However, there are still questions "
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    ABSTRACT: The kinetics of thermal decomposition of cellulose wadding was investigated from TG–MS experiments. Different oxygen concentrations in the atmosphere and several heating rates were used to study the influence of oxygen concentration on the mass loss of the sample and on the emission of gases. A shift and an amplitude variation of the DTG curves as well as an increase of the emission of gases such as CO and CO2 were observed. Then, a kinetic model was proposed to predict the mass loss of the cellulose wadding. Three stages were considered: the cellulose pyrolysis, the char oxidation and the decomposition of calcium carbonate. For the pyrolysis, the kinetic parameters were expressed according to the partial pressure of oxygen. For the char oxidation, a power law was used to account for the influence of oxygen whereas the other kinetic parameters were considered constant regardless of oxygen concentration. The decomposition of calcium carbonate was modelled by a first order influenced by the pressure of CO2.
    Thermochimica Acta 10/2011; 525(1):16-24. DOI:10.1016/j.tca.2011.07.016 · 2.18 Impact Factor
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    ABSTRACT: The decomposition behavior of cotton fibers is examined using thermogravimetric analysis. The effect of the test parameters on the thermal degradation of raw cotton fibers is determined. Focus is given to the influence of water immersion on the thermal behavior of cotton fibers. For less mature fibers a clear difference is noted between the degradation profiles of the water-immersed and untreated samples. On the contrary, only a small change is noted on the degradation profile for more mature fibers after water immersion. The maturity and variations in water-soluble content of the fiber are found to be important factors influencing the thermal behavior of raw cotton fibers. Inductively coupled plasma atomic emission spectrometry (ICP-AES) is used to underpin the effect of water immersion on cotton fibers. This improved understanding for the role of maturity and water soluble constituents in thermal degradation of cotton fibers may lead to develop routes that improve thermal stability and smoldering characteristics of cotton fibers as relevant for future applications.
    Cellulose 08/2013; 20(4). DOI:10.1007/s10570-013-9936-0 · 3.57 Impact Factor
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