Synthesis of reduced graphene oxide functionalized with imidazolium based ionic liquid composite for adsorptive removal of acetamiprid and Fipronil

Pesticide-contaminated industrial effluents remain a major environmental challenge due to inadequate wastewater treatment. Reduced graphene oxide–ionic liquid (rGO-IL) composites have recently emerged as efficient materials for pollutant removal. In this study, a novel composite of reduced graphene oxide (rGO) functionalized with 1,3-di[1H-imidazol-1-yl]-2-propanol (DIPO) ionic liquid, (rGO-DIPO) was fabricated via co-precipitation method as an efficient adsorbent for the removal of acetamiprid and fipronil pesticides from aqueous environment. The composite was characterized using SEM, FTIR, XRD, and EDX, confirming successful functionalization. The XRD results showed that the rGO-DIPO composite exhibited a monoclinic structure likely due to the sequential orientation of DIPO molecules intercalated between rGO sheets with a crystallite size of 15.63 nm. The FTIR analysis confirmed the synthesis of rGO, DIPO and the final rGO-DIPO composite. SEM analysis revealed that rGO exhibited a layered, wrinkled sheet-like structure with irregular shapes, while the rGO-DIPO composite showed a smoother, denser surface with an interconnected network and an average particle size of 15.25 μm. EDX analysis confirmed the presence of carbon and oxygen as dominant elements in both rGO and rGO-DIPO, with increased carbon content in rGO-DIPO indicating successful ionic liquid incorporation. The rGO-DIPO composite exhibited excellent adsorption capacities under optimized conditions for acetamiprid (pH 13, 40 min, 6 mg sorbent dosage, 50 ppm sorbate concentration, and 30 °C) and fipronil (pH 13, 60 min, 6 mg sorbent dosage, 40 ppm sorbate concentration and 30 °C). Kinetic studies revealed that the adsorption of both pesticides followed pseudo-second-order kinetics. The adsorption data best fitted the Langmuir isotherm model, confirming favorable homogeneous physiosorption with calculated q e values of 89.61 mg/g and 108.81 mg/g for acetamiprid and fipronil respectively, which were highly concordant to the experimental q e values. Thermodynamic analysis revealed that the adsorption process was exothermic, spontaneous, and entropy-decreasing. Additionally, the rGO-DIPO composite exhibited remarkable reusability, maintaining adsorption capacity upto five cycles. These findings highlight the robust potential of rGO-DIPO as a highly effective and reusable adsorbent for the removal of harmful pesticides from wastewater.