Adsorptive removal of sulphonamides in water by graphene oxide-doped porous polycarbonate derived from optical disc waste

Upcycling e-waste polycarbonate into a potential adsorbent material to remove sulphonamide residuals in the aquatic system could simultaneously facilitate the management of e-waste plastics and the remediation of wastewater. Hence, this work presents the application of a porous graphene oxide/polycarbonate solid phase prepared through thermally impacted non-solvent-induced phase separation for the adsorptive removal of sulphacetamide, sulphadiazine, sulphamethazine, sulphamethoxazole, and sulphathiazole in the aqueous phase. The polycarbonate recovered from optical disc waste was doped with a small amount of graphene oxide to produce a nest-like structure with enhanced surface area, improved thermal stability, and adsorptive ability towards sulphonamides. The effects of experimental factors on the adsorption capacity towards sulphonamides were also examined; the response surface model suggested optimum conditions of around pH 7, initial sulphonamide concentration of 15 ppm, adsorbent dosage of 0.08 g, and contact time of 4.3 h. Regardless of the type of sulphonamide, the empirical data best fitted the pseudo-second-order adsorption kinetic model and followed Langmuir isotherms, revealing that the favourable chemisorption process consisted entirely of a monolayer mechanism at the adsorbent surface. The product exhibited comparable adsorptive performance in different water matrices, with recoverability and reusability of up to 4 cycles. Overall, the waste-derived adsorbent poses great potential for application in wastewater treatment.

Automated summary

This study presents the application of a porous graphene oxide/polycarbonate solid phase derived from upcycled e-waste as an effective adsorbent for removing sulphonamide residuals in wastewater. The adsorbent exhibited enhanced adsorptive ability towards sulphonamides due to its nest-like structure, high surface area, and improved thermal stability. The optimal adsorption conditions were determined, and the adsorption process was found to follow pseudo-second-order kinetics and Langmuir isotherms. The waste-derived adsorbent showed comparable performance in different water matrices and could be reused for up to 4 cycles, highlighting its great potential for wastewater treatment.