Enhanced adsorption of malathion and phoxim by a three-dimensional magnetic graphene oxide-functionalized citrus peel-derived bio-composite

Abstract

By integrating the steps of direct magnetization and one-pot pyrolysis, a three-dimensional (3D) magnetic graphene oxide-functionalized citrus peel-derived bio-composite (mGOBC) was synthesized and characterized successfully, and it was proved to possess a three-dimensional (3D) porous architecture and graphitic structure. Its potential as an enrichment adsorbent was investigated using adsorption kinetics and adsorption isotherm models to establish an effective analytical method for the determination of organophosphorus pesticides (OPPs) in vegetables. The experimental results indicated that the adsorption was better fitted with the pseudo second order model and Langmuir isotherm model, and the maximum adsorption capacities for malathion and phoxim were 25.26 mg g⁻¹ and 42.31 mg g⁻¹, respectively. It was found that the graphitic structure of mGOBC resulted in π–π EDA (electron donor–acceptor) interaction with the benzene rings, electron-donating N, P, and S atoms in the analytes, which assisted adsorption. Subsequently, Plackett–Burman (P–B) experimental design, central composite design (CCD) and response surface methodology (RSM) were employed to develop an analytical method based on the mGOBC adsorbent. Under optimal conditions, the developed method is accurate and precise. The novel synthesized mGOBC can efficiently achieve removal and trace determination of harmful OPPs.