Green synthesis of a novel CuFe2O4@activated carbon magnetic nanocomposite from black seed (Nigella sativa L.) industrial processing waste: Physicochemical properties and sorption behavior toward oxytetracycline hydrochloride antibiotic

In this study, activated carbon (BAC) produced from black seed ( Nigella sativa L.) industrial processing solid wastes was converted into a novel magnetically separable activated carbon nanocomposite (CuF@BAC) material by using a microwave-assisted chemical co-precipitation method in a basic medium with copper ferrite nanoparticles (CuFe ₂ O ₄ : CuF). It was characterized by vibrating sample magnetometer (VSM), scanning electron microscopy-energy dispersive X-ray (SEM-EDX), nitrogen gas sorption-desorption, X-ray diffraction (XRD), Raman, Fourier transform infrared spectroscopy (FTIR), Boehm titration, and point of zero charge ( pH _PZC ) analysis techniques. Moreover, its ability to remove oxytetracycline hydrochloride (OTC) antibiotic from water was tested. The BET surface area, total pore volume, average pore diameter, mesopore contribution, and saturation magnetization values of CuF@BAC were determined as 455 m ² /g, 0.280 cm ³ /g, 2.5 nm, 64.5%, and 15.01 emu/g, respectively. Kinetic and equilibrium sorption data are well-fit by the pseudo-second-order and Langmuir models, respectively. The maximum amount of OTC removed by CuF@BAC was 669 mg/g. The thermodynamic parameters indicated that the process was spontaneous and endothermic. Regeneration studies performed with HCl for each sorbate showed it had reusable stability at high sorption efficiency for up to four cycles. This study revealed that CuF@BAC is a promising green sorbent due to its high sorption efficiency, easy magnetic separation, and reusable properties.