NOVEL SYNTHESIS OF GRAPHENE OXIDE (GO) FROM PYROLYZED WASTE TIRE: TUNING THE OXIDATION DEGREE VIA VARYING KMnO4

Abstract

Graphene oxide (GO) is highly valued for its tunable properties, making them versatile for high-performance applications. Reliance on high-purity graphite flakes as the primary precursor increases production cost and raises environmental concerns, highlighting the need for sustainable alternatives. Converting carbon from waste materials into GO offers a green approach, but remains challenging due to their heterogenous composition and lower graphitic order compared to conventional graphite. Thus, this research presents the synthesis and characterization of GO from recovered carbon black (rCB) of pyrolysis waste tires through modified Hummers’ method, with a focus on tuning the concentration of oxidizing agent (KMnO₄). The synthesized materials were thoroughly analyzed using X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), and field emission scanning electron microscope-energy dispersive X-ray (FESEM-EDX). Results show that increasing KMnO₄ concentration promoted the oxidation and exfoliation of rCB to GO, as shown by the XRD peak shifting to a lower angle (2θ = 11.23°), which was first observed at a KMnO₄ concentration of 3 g. FTIR analysis revealed that increasing KMnO₄ concentration enhanced the oxidation of rCB, as supported by the increase in the absorption bands at 3395 cm^-1 (O-H), 1735 cm^-1 (C=O), and 1215 cm^-1 (C-O) in GO-5 samples, indicating successful incorporation of oxygen-containing functionalities with higher oxidation levels. FESEM images further supported these findings, showing a morphological transformation from aggregated spherical particles in raw rCB to thin, wrinkled GO sheets at higher KMnO₄ concentrations, indicating successful exfoliation and GO formation. These findings demonstrate that controlling the concentration of KMnO₄ influences the oxidation degree and structural properties of synthesized GO from carbon source derived from waste and provides a promising pathway for recycling waste into high-value materials.