Fe-metal-organic-framework/MnO2 nanowire/granular activated carbon nanostructured composites for enhanced As(III) removal from aqueous solutions

Abstract

The elimination of arsenic pollution has attracted increasing concerns due to its toxicity and severe carcinogenicity. Herein, we proposed an in-situ crystal growth strategy without surfactant to fabricate MIL-88B uniformly anchored on the surface of MnO2/GAC (MIL-88B/MnO2/GAC). Such innovative MIL-88B/MnO2/GAC nanostructured composites not only exhibited the synergetic functions of simultaneously oxidizing As(III) and adsorbing the generated As(V), but also effectively reduced the cost of metal–organic frameworks (MOFs) adsorbents. Impressively, the as-prepared sample achieved remarkably boosted As(III) removal capacity of 15.13 mg g−1 compared to 4.1 mg g−1 of MnO2/GAC composite and 2.1 mg g−1 of GAC, which was mainly ascribed to the synergistic effect between the excellent adsorption abilitiy of MIL-88B and oxidation property of MnO2/GAC. Owing to the unique construction and properties, the constructed MIL-88B/MnO2/GAC composites presented a desirable As(III) removal ability under a wide pH scope of 2 to 10. Moreover, the possible mechanism of the synergistic removal over MIL-88B/MnO2/GAC was elucidated by X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR) and radical trapping experiment. This work not only offers a superior bifunctional catalyst for high-efficient removal of arsenic, but also provides a new perspective for rational construction of MOF derivatives for their further applications.