| Summary: | 碩士 === 大葉大學 === 環境工程學系碩士班 === 102 === In this study, we use the pyrolysis method to treat the plastic and printed circuit board (PCB) of waste mobile phone, breaking it down into solid residue, oil/gas fuel to increase the benefit for recycling. However, the exit of Br may affect the quality of pyrolysis oil. Therefore, the reactants of Ca(OH)2 and CaCO3 are added in the samples during the pyrolysis process to investigate the distribution of Br in the products.
After dismantling the mobile phones, the percentages of plastic, screen, PCB and others are 38.17, 7.39, 32.95, and 21.49%, respectively. The Br is observed only in the PCB (about 3.31%). There is no effect of adding reactants on the reaction temperature for the pyrolysis of PCB under the constant heating rate experiments. But the final mass of residues is different for degradation of PCB adding different reactant.
The distribution of Br in the pyrolysis products are determined with/without adding reactants of Ca(OH)2 and CaCO3. PCB pyrolysis at 700℃ without reactant, there are 17.1 and 9.5 % of Br distributed in solid residues and liquid products, the remain Br (73.4 %) is distributed in gas products. Adding Ca(OH)2 in sample, the amount of Br distributed in the solid residues increase by 34.4 % for reaction temperature 700℃ and the ratio of PCB/Ca(OH)2 = 1/0.5, but 6.3 and 28.1 % decrease in liquid and gas product. Adding CaCO3 in sample, the amount of Br distributed in the solid residues increase by 19.4 % for reaction temperature 700℃ and the ratio of PCB/Ca(OH)2 = 1/0.5, but 7.4 and 12 % decrease in liquid and gas product. Comparing the results for adding two reactants, the Br is most effectively retained in the solid residues under the mole ratio of Ca/Br = 9.11 and T = 500℃.
After analyzing the products, Cu (70600 ppm) is the main component in the pyrolysis residues of PCB. Large amount of Ca remained in the solid residues, which is in the proportion to the reactants added. The main species of the liquid products are phenolic derivatives (62.69 %), which may be released from the degradation of the constituent material (epoxy resin) of PCB. The amount of phenol is up to 25 % in the liquid products. The main component of gaseous products is CO2. The CH3Br is observed in the gas product for the pyrolysis without reactant added, but not detected for the case with reactant.
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