Ultra-effective removal of methylene blue dye and lead heavy metal from aqueous solution using novel Co and Fe co-doped magnetic activated carbon nanohybrid material from Nigella sativa (Nigella sativa L.) industrial processing wastes

In this study, a novel magnetic carbonaceous nanohybrid material (CoF@NAC) was synthesized by microwave-assisted simple chemical co-precipitation method in the basic medium using iron and cobalt nitrate salts in the presence of Nigella sativa (Nigella sativa L.) industrial processing waste-based activated carbon (NAC) and then characterized by SEM, EDX, Mapping, BET, XRD, VSM, FTIR, Boehm titration, and pH_ZPC techniques. Its BET surface area, total pore volume, mesoporosity, average pore diameter, and saturation magnetization values were 729 m²/g, 0.426 cm³/g, 61.5%, 2.4 nm, and 23.3 emu/g, respectively. To test its adsorptive performance, methylene blue (MB) dye and lead (Pb(II)) heavy metal water pollutants were selected as model adsorbates. Optimum adsorption conditions were determined according to the maximum effects of key experimental parameters. The kinetic and isotherm findings of each adsorption system fit best the pseudo-second-order kinetic and Langmuir isotherm models, respectively. The maximum removed MB and Pb(II) quantities of MB and Pb(II) were 667 and 455 mg/g, respectively, at their natural pH levels (pH 6 for MB and pH 5 for Pb(II)) in water. Thermodynamic parameters calculated showed that their processes were spontaneous, endothermic for MB, and exothermic for Pb(II). Moreover, it showed high recyclability stability over four cycles for the studied adsorbates.