Abstract
Exposure of humans to Arsenic from groundwater drinking sources is an acute global public health problem, entailing the urgent need for highly efficient/low-cost Arsenite (As(III)) up-taking materials. Herein we present an innovative hybrid-material, ZrMOF@SF(d) operating like an "As(III)-sponge" with unprecedented efficiency of 1800 mg As(III) gr(-1). ZrMOF@SF(d) consists of a neutral Zirconium Metal-Organic Framework [ZrMOF] covalently grafted on a natural silk-fiber (SF(d)). ZrMOF itself exhibits As(III) adsorption of 2200 mg gr(-1), which supersedes any -so far- known As(ΙΙΙ)-sorbent. Using XPS, FTIR, BET-porosimetry data, together with theoretical Surface-Complexation-Modeling (SCM), we show that the high-As(ΙΙΙ)-uptake is due to a sequence of two phenomena:[i] at low As(III)-concentrations, surface-complexation of H(3)AsO(3) results in As(III)-coated voids of ZrMOF, [ii] at increased As(III)-concentrations, the As(III)-coated voids of ZrMOF are filled-up by H(3)AsO(3) via a partitioning-like mechanism. In a more general context, the present research exemplifies a mind-changing concept, i.e. that a "partitioning-like" mechanism can be operating for adsorption of metalloids, such as H(3)AsO(3,) by metal oxide materials. So far, such a mechanism has been conceptualized only for the uptake of non-polar organics by natural organic matter or synthetic polymers.