Catalytic application of carbon nanotubes obtained from plastic solid waste in the removal of quinoline from isooctane by selective oxidation with hydrogen peroxide

• Author(s): Piccinin, Larissa
• Date: 2022
• Persistent ID: http://hdl.handle.net/10198/25583
• Origin: Biblioteca Digital do IPB
• Subject(s): Oxidative denitrification; Quinoline; Biphasic oxidation; Carbon nanomaterials; Hydrogen peroxide
• Document Type: Master thesis
• Language: English
• Contributor(s): Biblioteca Digital do IPB; Gomes, Helder; Vieira, Admilson Lopes; Díaz de Tuesta, Jose Luis

Description

Different carbon nanotubes were tested in two-phase oxidative processes using hydrogen peroxide as oxidant in order to remove and degrade a model contaminant, quinoline, from isooctane, which simulated contaminated fossil fuels. The CNTs were produced by chemical vapor deposition (CVD) from different polymers. The use of low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP) and a mixture of these three in the proportion of 35:25:40, respectively, resulted in the CNTs defined as CNT LDPE 600, CNT LDPE 800, CNT HDPE 800, CNT PP 800 and CNT MIX 800, where 600 or 800 represent the temperature of pyrolysis considered in the synthesis. The use of such polymers simulated the production of CNTs from residual plastic. Prior to the biphasic oxidation runs, the organic phase underwent oxidation tests, being concluded that isooctane was not oxidized under the conditions used. Possible adsorption on the materials was also tested in the organic phase and in the biphasic medium. In both cases no significant adsorption was obtained. The produced CNTs were tested as catalysts in the oxidative processes of hydrogen peroxide in aqueous solution (CWPO) and in the biphasic medium. The performance of each material was analyzed in 24-hour reaction tests, at 80 °C, through monitorization of H2O2 degradation, quinoline concentration in oily and aqueous media, total organic carbon concentration, aromatics concentration in oily and aqueous media, and pH measurement. In addition to the tests carried out with the CNTs produced, a commercial CNT was also tested for comparison. Finally, all catalysts used fulfilled the proposed objective, 100% of quinoline being removed from the oily phase in the biphasic oxidation runs, up to 8 h of reaction, and degrading 100% of the contaminant by CWPO in 4 h. Other analyses revealed a complete degradation of H2O2 with all CNTs in the CWPO tests and in the biphasic oxidation runs, except for the commercial CNT in the biphasic oxidation run. The analysis of TOC and aromatics concentration show significant decreases with all tested carbon nanomaterials, while pH had a slight decrease in the CWPO runs and an increase in the biphasic oxidation runs. In summary, all carbon materials produced were efficient in the proposed process and are comparable to the performance obtained by the commercial CNT.