Kinetic Study of the Pyrolysis of Waste Printed Circuit Boards Subject to Conventional and Microwave Heating
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This paper describes a kinetic study of the decomposition of waste printed circuit boards (WPCB) under conventional and microwave-induced pyrolysis conditions. We discuss the heating rates and the influence of the pyrolysis on the thermal decomposition kinetics of WPCB. We find that the thermal degradation of WPCB in a controlled conventional thermogravimetric analyzer (TGA) occurred in the temperature range of 300 °C–600 °C, where the main pyrolysis of organic matter takes place along with an expulsion of volumetric volatiles. The corresponding activation energy is decreased from 267 kJ/mol to 168 kJ/mol with increased heating rates from 20 °C/min to 50 °C/min. Similarly, the process of microwave-induced pyrolysis of WPCB material manifests in only one stage, judging by experiments with a microwave power of 700 W. Here, the activation energy is determined to be only 49 kJ/mol, much lower than that found in a conventional TGA subject to a similar heating rate. The low activation energy found in microwave-induced pyrolysis suggests that the adoption of microwave technology for the disposal of WPCB material and even for waste electronic and electrical equipment (WEEE) could be an attractive option.Keywords:
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Abstract The Ni(II), Cu(II) Co(II) and Zn(II) complexes of 2,3‐hydroxyimino‐4‐phenyl‐6‐phenyazo‐1‐thia‐4,5‐diaza‐ cyclohexa‐5‐diene (H 2 L) were synthesized. Thermal behavior of these complexes was studied in dynamic nitrogen atmosphere by TA (thermogravimetric analysis), DTA (differential thermal analysis) and DTG (differential thermal gravimetry) techniques. The reaction order, the activation energies, the entropies, the enthalpies, the free energies, and the pre‐exponential factors of the thermal decomposition reactions were calculated from the thermogravimetric curves. The kinetic analysis of the thermogravimetric data was performed by using several methods such as MacCallum‐Tanner (MT), van Krevelen (vK), Madhusudanan‐Krishnan‐Ninan (MKN), Wanjun‐Yuwen‐Hen‐Cunxin (WYHC), Horowitz‐Metzger (HM) and Coats‐Redfern method (CR) based on the single heating rate. Most appropriate methods were determined for each decomposition step according to the least‐square linear regression. The Ni(II), Cu(II) Co(II) and Zn(II) complexes displayed one‐ or two‐stage decomposition pattern when heating in a dynamic nitrogen atmosphere and metal oxides remained as end products of the complexes. The characterization of the end products of the decomposition was performed by X‐ray diffraction.
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Diene
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Differential thermal analysis
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Polyacrylamide
Degradation
Atmospheric temperature range
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The thermal decomposition kinetics of RDX at different rates was studied by thermogravimetric analyzer(TG) and the activation energy of RDX was calculated by distributed activation energy model. It is shown that the thermal decomposition processes of RDX were divided into three stages according to the TG curves, they are molten stage, thermal decomposition stage and eng stage. The activation energies of RDX are all between 124.34 and 181.48KJ•mol-1 in the thermal decomposition stage of non-monotonously increasing. The activation energy of RDX is 139.98 KJ•mol-1 in the molten stage, and the thermal decomposition stage is167.24KJ•mol-1.
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Abstract The thermal degradations of methyl methacrylate‐graft‐natural rubber (MG) at different heating rates ( B ) in nitrogen were studied by thermogravimetric analysis. The results indicate that the thermal degradation of MG in nitrogen is a one‐step reaction. The degradation temperatures increase along with the increment of heating rates. The temperature of initial degradation ( T 0 ) is 0.448 B + 362.4°C, the temperature at maximum degradation rate, that is, the peak temperature on a differential thermogravimetric curve ( T p ) is 0.545 B + 380.7°C, and the temperature of final degradation ( T f ) is 0.476 B + 409.4°C. The degradation rate at T p is not affected by B , and its average value is 48.9%; the degradation rate at T f is not affected by B either, and its average value is 99.3%. The reaction order ( n ) is 2.1 and is not affected by B . The reaction activation energy ( E ) and the frequency factor ( A ) increase along with B , and the apparent reaction activation energy ( E 0 ) is 254.6 kJ/mol. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2952–2955, 2002
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In this study, thermochemical conversion of plastic wastes (PET and PVC) together with an agricultural waste (hazelnut shell) was investigated. In order to determine the thermal and kinetic behaviours, pyrolysis experiments were carried out from room temperature to 800 °C, with a heating rate of 10 °C min(-1) in the presence of a N2 atmosphere in a thermogravimetric analyzer. With the obtained thermogravimetric data, an appropriate temperature was specified for the pyrolysis of biomass-plastic wastes in a fixed-bed reactor. At the second step, pyrolysis experiments were carried out at the same conditions with the thermogravimetric analyzer, except the final temperature which was up to 500 °C in this case. After pyrolysis experiments, pyrolysis yields were calculated and characterization studies for bio-oil were investigated. Experimental results showed that co-pyrolysis has an important role in the determination of the pyrolysis mechanism and the process conditions while designing/implementing a thermochemical conversion method where biomass-plastic materials were preferred as raw materials.
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Experiments on the thermal decomposition of CuSe were carried out by using a thermogravimetric analyzer (TGA) at different heating rates. The kinetic parameters and mechanisms were discussed based on model-free and model-based analyses. The decomposition rate and decomposition behavior of CuSe were investigated by using a vacuum thermogravimetric furnace. The results showed that the R3 model was identified as the most probable mechanism function under the present experimental conditions. The average values of activation energy and the pre-exponential factor were 12.344 J/mol and 0.152 s-1, respectively. The actual decomposition rate of CuSe was found to be 0.0030 g/(cm2·min).
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Abstract Thermal decomposition of ZnHg(SCN) 4 (ZMTC) in air was investigated by means of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The intermediates and final products of the thermal decomposition were identified by X‐ray powder diffraction at room temperature. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
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