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 KF 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.