Plastic waste-derived carbon nanotubes: Influence of growth catalyst and catalytic activity in CWPO

• Main Author: Fontana Roman, Fernanda
• Publication Date: 2025
• Other Authors: Silva, Adriano S., Tuesta, Jose L. Diaz de, Baldo, Arthur P., Lopes, Jessica P.M., Gonçalves, Giane, Pereira, Ana I., Praça, Paulo, Silva, Adrián M.T., Faria, Joaquim L., Bañobre-López, Manuel, Gomes, Helder
• Format: Article
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://hdl.handle.net/10198/34394
• topic: Plastic solid waste; Advanced oxidation processes (AOPs); Heterogeneous Fenton; Acetaminophen; Contaminants of emerging concern; Carbocatalysts

Low-density polyethylene (LDPE) was used in this work to grow carbon nanotubes (CNTs) by chemical vapor deposition (CVD) over catalysts based on Ni, Fe and Al, synthesized either by co-precipitation (C) or wet impregnation (I) methods, with CNT yields in the range of 16–33 %. The morphology of the CNTs was directly influenced by the route used for the CVD catalyst synthesis, with co-precipitation-derived CVD catalysts resulting in CNT samples with curly walls. CNTs were purified with H2SO4 (10–50 wt.%) to remove attached metal par- ticles. All synthesized materials (CVD-catalysts, as-synthesized CNTs, and purified CNTs) were tested as catalysts in the catalytic wet peroxide oxidation (CWPO) of paracetamol (PCM), chosen as a model pharmaceutical compound. Removals of 100 % of PCM in 8 h and 71 % of total organic carbon (TOC) in 24 h were achieved, with an H2O2 consumption efficiency of 76 % in 24 h for purified CNT (CNT@NiFeAl-C-P). The same CVD-catalyst (NiFeAl-C) was used to grow CNTs using real LDPE waste, and it was tested under the same reaction condi- tions, resulting in a PCM and TOC abatement of 90 % and 65 %, respectively. The synthesis of CNTs using LDPE waste was a good alternative, given the environmental benefits associated with its reintroduction into the economic cycle as a material with higher value than initially (upcycling).