Waste-to-wealth: Sustainable Conversion of Polyester Waste into Porous Carbons As Efficient Solar Steam Generators

Converting polyesters into carbon materials for energy and environmental applications provides a promising way to recycle urban and industrial waste plastics. However, previous strategies could not precisely control the crosslinking reaction of polyester. Herein, poly(ethylene terephthalate) (PET) is transformed into O,S-doped hierarchically porous carbon (OSHPC) using sodium lignosulfonate (SLS) and ZnO at 550 degrees C. SLS/ZnO show a synergistic effect on the PET carbonization. Firstly, a crosslinking structure is generated through esterification of carboxylic acid in PET degradation products with hydroxyl group in SLS. Subsequently, ZnO promotes de-carbonylation of crosslinking structure into vinyl-terminated chains and radical species to form carbon framework with rich micropores. Upon ZnO removal, numerous mesopores/macropores are introduced. OSHPC thereby bears micro-/meso-/macropores with rich chemical groups, which favor for water transportation. Meanwhile, the bead-like particles in OSHPC improve sunlight absorption. The combined advantages endue OSHPC with high performance in solar vapor generation to produce freshwater from wastewater/seawater. The evaporation rate under 1 kW/m(2) is 1.51 kg/m(2)/h, and the metallic ion removal efficiency is >99.9%. This work reutilizes waste polyesters to fabricate functional carbon and contributes to environmental remediation and solar energy exploitation. (c) 2020 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.