Enhanced arsenite adsorption from water by activated MOF embedded in macroporous chitosan bionanocomposite beads

Water remediation from arsenite [As(III)] is critical to environmental sustainability and human health. Metal-organic frameworks (MOFs) hold great promise for this purpose, while their efficient application requires addressing loading and activation issues. Herein, a new bionanocomposite bead UiO-66/CB was fabricated through simple gelation followed by the freeze-casting method for remediation of As(III)-contaminated water. Highly accessible UiO-66 nanoparticles are uniformly dispersed within the networking pores of the macroporous chitosan bead with high activity retention. Moreover, the fabrication strategy effectively activated the embedded UiO-66 nanoparticles, leading to improving the utilization efficiency of the active sites. The millimeter-sized UiO-66/CB-2.0 performed much more efficiently than the freely dispersed UiO-66 nanoparticles in removing As(III) and even exhibited comparable adsorption to the activated UiO-66 nanoparticles. The maximal sorption capacity of As(III) onto UiO-66/CB-2.0 was larger than 47.9 mg/g (88.6 mg As/g UiO-66) at pH 7. 1 g/L UiO-66/CB-2.0 can reduce As(III) levels (200 μg/L) in groundwater to below 10 μg/L. It could be readily regenerated and reused. Fixed-bed column adsorption by using UiO-66/CB-2.0 could treat ∼1600 bed volumes of As(III)-spiked groundwater to below 10 μg/L. This research provides a versatile route to fabricate high-performance and convenient MOFs biocomposite adsorbents for As(III) remediation.