Carbon/FexOy magnetic composites obtained from PET and red mud residues: paracetamol and dye oxidation

• Published in: Environmental technology Vol. 40; no. 21; pp. 2840 - 2852
• Main Authors: Sousa, Leonardo S., Chagas, Poliane, Oliveira, Luiz Carlos Alves de, Castro, Cinthia Soares de
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 19.09.2019; Taylor & Francis Ltd
• Subjects: Activation; Analgesics; Aqueous solutions; Basicity; Carbon content; Carbon dioxide; Catalysis; Catalysts; Catalytic activity; Composite materials; Contaminants; Dye industry wastes; Heat treatment; Hematite; heterogeneous fenton; Iron oxides; Magnetite; Methylene blue; Mud; Oxidation; Oxides; Paracetamol; PET waste; Pollutant removal; Red mud; Residues; Surface area; Wastewater treatment
• ISSN: 0959-3330; 1479-487X
• DOI: 10.1080/09593330.2018.1457723

Composite materials from PET and red mud (RM) wastes were used as catalysts for environmental application such as the wastewater treatment. The PET-RM catalysts were obtained by a mechanical mixture of the residues followed by thermal treatment under an N 2 atmosphere (300°C/1 h). An additional activation of the composites with CO 2 was investigated (at 800-900°C) to reduce the red mud basicity. The CO 2 activation affected the composites surface area and reduced their carbon content. XRD revealed that the haematite (α-Fe 2 O 3 ) and maghemite/magnetite are the main iron oxides present in the composites. Mössbauer characterization indicated the formation of reduced iron species (Fe 2+ ), highly reactive, after the composites heat treatment. The materials were very active catalysts for methylene blue (MB) and paracetamol (PRC) removal from aqueous solution. The catalytic activity revealed to be dependent on the surface area and mainly of the presence of reduced iron species in the catalysts. The MB removal reached 97% for both PET-RM 800/2 h and PET-RM 800/5 h, after 1 h of reaction. In the case of PRC, the highest removal was also obtained for PET-RM 800/2 h and PET-RM 800/5 h, of ≈25% and 40%, respectively. The contaminants removal mechanism likely occurred through combined adsorption and Fenton-like oxidation processes.