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

The elimination of arsenic pollution has attracted increasing concerns due to its toxicity and severe carcinoge-nicity. 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 nano -structured 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) ad-sorbents. 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.

Automated summary

In this study, a surfactant-free in-situ crystal growth strategy was proposed to fabricate MIL-88B/MnO2/GAC nano-composites. The as-prepared materials exhibited excellent oxidizing and adsorbing properties for As(III) removal, and showed desirable performance over a wide pH range. The synergistic removal mechanism was elucidated using various experimental techniques.