Magnetic activated carbon synthesized using rubber fig tree leaves for adsorptive removal of tetracycline from aqueous solutions

The current study emphasizes the activated carbon fabrication from rubber fig leaves, the establishment of its composite with iron oxide nanoparticles (RFAC@Fe₂O₃), and its relevance in the adsorptive elimination of tetracycline. The physical and functional properties of RFAC@Fe₂O₃ nanocomposite were uncovered by multiple approaches. Elemental analysis portrayed the existence of carbon, oxygen, and iron, while FESEM analysis revealed that Fe₂O₃ nanoparticle agglomerates were entrenched in the activated carbon matrix rendering it a rough abrasive texture. FT-IR analysis reported the presence of functional groups attributing to C[dbnd]C, –OH, crystalline iron oxide, and Fe–O stretching vibrations, and XRD corroborated graphitic crystalline structure, oxygenated functional groups attached to carbon accompanied by crystalline plane corresponding to Fe₂O₃ nanoparticles. XPS spectra depicted signature peaks for C, O, and Fe, while VSM studies designated its superparamagnetic nature. The high surface area (662.73 m²/g), pore size (3.12 nm), and mesoporous nature of RFAC@Fe₂O₃ make it apt for the adsorption of pollutants from contaminated samples. The adsorption of tetracycline (50 ppm) by RFAC@Fe₂O₃ was maximum at pH 4.0. As the nanocomposite dosage and stirring speed increased to 2.0 g/L and 150 rpm, maximum adsorption was observed due to more active binding sites and improved mixing. Freundlich isotherm along with pseudo-second-order model well described adsorption process divulging that tetracycline was adsorbed onto RFAC@Fe₂O₃ composite in multi-layers by chemisorption. Thermodynamic analysis signified negative values for ΔG°, while positive values for ΔH° and ΔS were obtained, indicating spontaneous feasible endothermic adsorption.