School of Chemistry and Chemical Engineering, University of Surrey, GU2 7XH Guildford, UK; Inorganic Chemistry Department & Materials Science Institute, University of Seville-CSIC, Avda. Américo Vespucio 49, 41092 Sevilla, Spain
Marielis C. Zambrano
Department of Forest Biomaterials, College of Natural Resources, North Carolina State University, Raleigh, NC 27695-8005, USA
Joel J. Pawlak
Department of Forest Biomaterials, College of Natural Resources, North Carolina State University, Raleigh, NC 27695-8005, USA
Richard A. Venditti
Department of Forest Biomaterials, College of Natural Resources, North Carolina State University, Raleigh, NC 27695-8005, USA
Tomas Ramirez Reina
School of Chemistry and Chemical Engineering, University of Surrey, GU2 7XH Guildford, UK; Inorganic Chemistry Department & Materials Science Institute, University of Seville-CSIC, Avda. Américo Vespucio 49, 41092 Sevilla, Spain
Jose Antonio Odriozola
Inorganic Chemistry Department & Materials Science Institute, University of Seville-CSIC, Avda. Américo Vespucio 49, 41092 Sevilla, Spain
Melis S. Duyar
School of Chemistry and Chemical Engineering, University of Surrey, GU2 7XH Guildford, UK; Corresponding author
Summary: Microplastics fibers shed from washing synthetic textiles are released directly into the waters and make up 35% of primary microplastics discharged to the aquatic environment. While filtration devices and regulations are in development, safe disposal methods remain absent. Herein, we investigate catalytic hydrothermal carbonization (HTC) as a means of integrating this waste (0.28 million tons of microfibers per year) into the circular economy by catalytic upcycling to carbon nanomaterials. Herein, we show that cotton and polyester can be converted to filamentous solid carbon nanostructures using a Fe-Ni catalyst during HTC. Results revealed the conversion of microfibers into amorphous and graphitic carbon structures, including carbon nanotubes from a cotton/polyethylene terephthalate (PET) mixture. HTC at 200°C and 22 bar pressure produced graphitic carbon in all samples, demonstrating that mixed microfiber wastes can be valorized to provide potentially valuable carbon structures by modifying reaction parameters and catalyst formulation.
