Environmentally sustainable synthesis of reduced graphene oxide using Piper chaba stem extract and its adsorbent efficacy towards wastewater treatment

This study presents an environmentally sustainable method for the production of reduced graphene oxide (rGO) utilizing Piper chaba stem extract as a green reducing agent, and systematically evaluates its adsorption capabilities for removing methylene blue (MB) as a model dye. The effective reduction of graphene oxide (GO) to rGO was confirmed by a UV–vis redshift from 226 nm to 265 nm, demonstrating the recovery of the sp 2 carbon framework. This was further supported by the narrowing of the band gap of rGO (3.42 eV) compared to that of GO (4.27 eV). Additional analyses—including FTIR, Raman spectroscopy, TGA, and XRD—verified the elimination of oxygen functionalities and the reduction in interlayer spacing. Electron microscopy illustrated the creation of few-layer, exfoliated rGO sheets. The rGO displayed high methylene blue adsorption efficiency (95–80 %) and capacity (150–135 mg/g within 80 min). Kinetic and isotherm analyses aligned with the pseudo-second-order and Langmuir models, respectively, yielding a maximum adsorption capacity of 235.29 mg/g. These results highlight the potential of green-synthesized rGO for applications in environmental science. • Environmentally sustainable synthesis of reduced graphene oxide (rGO) using Piper chaba stem extract. • Formation of few-layer exfoliated rGO sheets with rGO's structural restoration. • High adsorption capacity (235.29 mg/g) towards methylene blue (MB) dye, showcasing its potential for sustainable environmental applications.