Facile and scalable synthesis of magnetite/carbon adsorbents by recycling discarded fruit peels and their potential usage in water treatment

In this study, apple, banana and orange peels were used as precursor compounds for the mass production of magnetite/carbon adsorbents. A so-called “soak-calcination” procedure was employed by firstly soaking these waste fruit peels in FeCl3 aqueous solutions and secondly calcining these precursors in the nitrogen atmosphere to yield final magnetite/carbon composites. This approach is quite simple and effective to synthesize carbon-based adsorbents on an industrial scale. The as-produced adsorbents feature the merits of appropriate ferromagnetism (>4 emu g−1), high adsorption capacity (several hundreds of milligrams per gram for adsorption of methyl blue, Congo red, rhodamine B and Cr6+ ions), and good regenerability (>85%).