From “white carbon” to “black carbon”: Upcycling discarded plastic bottles into shining porous chars for the removal of sulfamethoxazole from water

Recycling difficult-to-degrade plastics, also known as “white pollution”, is currently being researched in the fields of materials and the environment, which is an extremely challenging topic. In this study, a pyrolysis-activation method combined with multiple activators was developed to prepare stable porous plastic chars (PPCs) from discarded plastic bottles for removing the typical antibiotic sulfamethoxazole (SMX). Micro/mesopores were formed in the PPCs, with the specific surface area reaching 961.20 m 2 /g. C, O, and N were the main elements in the PPCs, and their atomic ratios showed the hydrophobicity and aromaticity. Graphite-like structures and abundant surface functional groups were generated in the PPCs. Unlike conventional char materials, impurities, such as aluminum oxide, have high reflectivity, resulting in the appearance of many shining spots. PPCs display a high sorption capability for SMX, with the maximum sorption quantity determined reaching 487.52 mg/g. Multilayer sorption is dominated by physical processes, and pore filling, partitioning, hydrogen bonding, π-π stacking, and electrostatic interactions are the main sorption processes. Chemical-like sorption and mass transfer control the sorption rate. Furthermore, PPCs have stable performance and good recyclability and could be used for practical applications. This study provides a novel strategy and an example of the upcycling of discarded plastic as an excellent char material for environmental remediation.