A novel integrated Cr(vi) adsorption–photoreduction system using MOF@polymer composite beads. Issue 19 (6th May 2020) - Valizadeh, Bardiya
Abstract : Herein, a novel integrated adsorption–photoreduction system, which captures highly mobile and toxic hexavalent chromium (Cr(vi )) from real-world water samples and reduces it to less mobile and benign Cr(iii ) species, was designed. Abstract : Herein, a novel integrated adsorption–photoreduction system, which captures highly mobile and toxic hexavalent chromium (Cr(vi )) from real-world water samples and reduces it to less mobile and benign Cr(iii ) species, was designed. To do this, a known Zr-MOF, UiO-66, was functionalized with double amino groups. This modification permits the new material, Zr-BDC-(NH2 )2, to play a dual-purpose as both adsorbent and photocatalyst. Next, Zr-BDC-(NH2 )2 was incorporated into MOF@polymer beads (M@PB) using polyethersulfone (PES) that was chemically modified with carboxylic acid groups to improve hydrophilicity. The modification enhances the Cr(vi ) extraction rate of the beads by a factor of ∼3 when compared to the unmodified counterpart. In addition, Zr-BDC-(NH2 )2 @PB offers one of the highest Cr(vi ) uptake capacities reported to date, rapid extraction rates, high selectivity for Cr(vi ) in real-world water samples, and full recyclability. The adsorption and subsequent regeneration cycles are carried out in a glass column equipped with a visible light source, demonstrating that the Cr(vi ) concentration is brought below drinkable levels, and the Cr(vi ) subsequently photoreduced to Cr(iii ) species using light irradiation during adsorbent regeneration. To the best of our knowledge, this is the first demonstration of MOF-based adsorption–photoreduction of Cr(vi ) in a single process.