Optimized photocatalytic degradation of 2-naphthol using ZnO/rGO nanocomposites synthesized from palm kernel shell waste

Abstract

The widespread use of 2-naphthol in various industries, coupled with its high toxicity and persistence as an organic pollutant, necessitates effective degradation methods. This study synthesized ZnO/reduced graphene oxide (rGO) nanocomposites (NCs) via a hydrothermal method for photocatalytic degradation of 2-naphthol. Graphene oxide (GO), derived from palm kernel shell waste through a modified Hummers method, was reduced to rGO using N,N-Dimethylformamide (DMF), which also facilitated ZnO nanomaterial formation on GO. Given the growing environmental concerns associated with hazardous pollutants, the development of such nanocomposites represents a promising advancement in photocatalytic technology for sustainable remediation. The GO loading was optimized to enhance performance, with results showing improved surface area and adsorption capacity. ZnO/rGO NCs with 10 % GO loading (ZR(10)) achieved 95 % 2-naphthol degradation after 120 min of irradiation, outperforming pure ZnO and other ZR NCs. ZR(10) retained 67.7 % activity after three reuse cycles, with a second-order kinetic rate constant of 0.0115 h⁻¹. Additionally, the catalyst maintained its ZnO crystal structure, demonstrating excellent stability. A potential degradation mechanism of 2-naphthol by ZR(10) is proposed. This study highlights the eco-friendly use of palm kernel shell waste as a carbon precursor and underscores the potential of ZnO/rGO as efficient photocatalysts for environmental remediation.