Removal of antibiotics from aqueous solution by using magnetic Fe₃O₄/red mud-nanoparticles

In this study, the availability of magnetically separable Fe₃O₄-red mud nanoparticles (Fe₃O₄-RM-NPs) for the removal of antibiotics from wastewater was investigated. Disadvantages of red mud and Fe₃O₄ because of difficult separation from aqueous media, agglomeration, and iron leaching were overcome by combining these two materials. After examinating adsorption capability of magnetic Fe₃O₄-RM-NPs for all studied antibiotic compounds, the experiments were performed by using Ciprofloxacin (CIPRO) as a model compound. Batch experiments were performed to determine the effect of red mud content of synthesized Fe₃O₄-RM-NPs, pH, reaction time and temperature on the proposed method. The surface morphology, magnetic properties, crystalline structure, thermal stability and Brunauer-Emmet-Teller surface area of the synthesized Fe₃O₄-RM-NPs were determined. The saturation magnetization of Fe₃O₄-RM-NPs was determined to be 12.2 emu/g, which is efficient to separate adsorbent from water by using a conventional magnet. For the efficient removal of CIPRO from aqueous media optimum conditions were determined to be 1.5 g red mud for Fe₃O₄-RM-NPs synthesize, pH 6.0, reaction time 60 min, 3 g/L Fe₃O₄-RM-NPs dosage at 25 °C. Adsorption was fitted well with pseudo-second-order kinetic model. Equilibrium data were found to be better represented by Freundlich isotherm. n value was 4.32, and K_F value was 110.15 mg/g for Freundlich isotherm. No important matrix effect was determined for removal of CIPRO from wastewater sample. Film diffusion mechanism controlled adsorption. Magnetically separable Fe₃O₄-RM-NPs are proposed to be used as efficient adsorbent to remove antibiotics from wastewater sources. Since red mud is a process waste, proposed nanomaterial is a good alternative to commercial adsorbents.