Publicação
Conversion of plastic solid wastes into carbon nanotubes: effect of operating conditions
| Resumo: | An efficient treatment of plastic waste brings remarkable environmental, social and economic benefits. Therefore, this work proposes the recovery of plastic waste by its conversion to carbon nanotubes (CNTs) by sequential pyrolysis and chemical vapor deposition (CVD). For this purpose, an alumina-supported iron material, prepared by the sol-gel method, was used as catalyst in chemical vapor deposition. This method allows to control the size of the formed carbon nanostructures. To understand the variables affecting the proportion and to maximize material yield, catalyst, flow rate and temperature at which CVD will occur were studied in this work. Three types of pure polymers were used as carbon precursors: low-density polyethylene (LDPE), high-density polyethylene (HDPE) and polypropylene (PP), as well as a mixture of them. The best conditions for the formation of CNTs was found to be 40 mL/min of nitrogen inflow and 800 °C for the polymers, with the following yields, respectively: 16.9 (LDPE), 8.5 (HDPE), 6.7 (PP) and 8.9 (MIX) %. The obtained samples were purified with 50 % H2SO4. Ash content, acidity and basicity, SBET, XRD and FT-IR, were considered for the characterization of the materials. In the ashes, the purification removed a good part of the inorganic content, as the acid-base titration it demonstrated that the CNTs had an acidic character confirmed by the FT-IR. XRD revealed that the iron phase in the catalyst produced was Fe2O3, and the determination of the ash content confirmed the XRD results by the red color of the material at the end. And by porosimetry analysis, they were shown to be materials within the range of 159-242 m2/g, with their adsorption and desorption graphs resulting in a mesoporous material, characteristic of nanotubes. |
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| Autores principais: | Freitas, Isabella Veronica |
| Assunto: | Carbon nanotubes Chemical vapour deposition Plastic waste Solid waste management Recovery technologies |
| Ano: | 2021 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Instituto Politécnico de Bragança |
| Idioma: | inglês |
| Origem: | Biblioteca Digital do IPB |
| Resumo: | An efficient treatment of plastic waste brings remarkable environmental, social and economic benefits. Therefore, this work proposes the recovery of plastic waste by its conversion to carbon nanotubes (CNTs) by sequential pyrolysis and chemical vapor deposition (CVD). For this purpose, an alumina-supported iron material, prepared by the sol-gel method, was used as catalyst in chemical vapor deposition. This method allows to control the size of the formed carbon nanostructures. To understand the variables affecting the proportion and to maximize material yield, catalyst, flow rate and temperature at which CVD will occur were studied in this work. Three types of pure polymers were used as carbon precursors: low-density polyethylene (LDPE), high-density polyethylene (HDPE) and polypropylene (PP), as well as a mixture of them. The best conditions for the formation of CNTs was found to be 40 mL/min of nitrogen inflow and 800 °C for the polymers, with the following yields, respectively: 16.9 (LDPE), 8.5 (HDPE), 6.7 (PP) and 8.9 (MIX) %. The obtained samples were purified with 50 % H2SO4. Ash content, acidity and basicity, SBET, XRD and FT-IR, were considered for the characterization of the materials. In the ashes, the purification removed a good part of the inorganic content, as the acid-base titration it demonstrated that the CNTs had an acidic character confirmed by the FT-IR. XRD revealed that the iron phase in the catalyst produced was Fe2O3, and the determination of the ash content confirmed the XRD results by the red color of the material at the end. And by porosimetry analysis, they were shown to be materials within the range of 159-242 m2/g, with their adsorption and desorption graphs resulting in a mesoporous material, characteristic of nanotubes. |
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