Millimeter-shaped metal-organic framework/inorganic nanoparticle composite as a new adsorbent for home water-purification filters

Altres ajuts: this work was also funded by the CERCA Program/Generalitat de Catalunya.Heavy-metal contamination of water is a global problem with an especially severe impact in countries with old or poorly maintained infrastructure for potable water. An increasingly popular solution for ensuring clean and safe drinking water in homes is the use of adsorption-based water filters, given their affordability, efficacy, and simplicity. Herein, we report the preparation and functional validation of a new adsorbent for home water filters, based on our metal-organic framework (MOF) composite containing UiO-66 and cerium(IV) oxide (CeO2) nanoparticles. We began by preparing CeO2@UiO-66 microbeads and then encapsulating them in porous polyethersulfone (PES) granules to obtain millimeter-scale CeO2@UiO-66@PES granules. Next, we validated these granules as an adsorbent for the removal of metals from water by substituting them for the standard adsorbent (ion-exchange resin spheres) inside a commercially available water pitcher from Brita. We assessed their performance according to the American National Standards Institute (ANSI) guideline 53-2019, "Drinking Water Treatment Units - Health Effects Standard". Remarkably, a pitcher loaded with a combination of our CeO2@UiO-66@PES granules and activated carbon at standard ratios met the target reduction thresholds set by NSF/ANSI 53-2019 for all the metals tested: As(III), As(V), Cd(II), Cr(III), Cr(VI), Cu(II), Hg(II), and Pb(II). Throughout the test, the modified pitcher proved to be robust and stable. We are confident that our findings will bring MOF-based adsorbents one step closer to real-world use

The Imine-Based COF TpPa-1 as an Efficient Cooling Adsorbent That Can Be Regenerated by Heat or Light

Adsorption-based cooling systems, which can be driven by waste heat and solar energy, are promising alternatives to conventional, compression-based cooling systems, as they demand less energy and emit less CO. The performance of adsorption-based cooling systems relates directly to the performance of the working pairs (sorbent-water). Accordingly, improvement of these systems relies on the continual discovery of new sorbents that enable greater mass exchange while requiring less energy for regeneration. Here, it is proposed that covalent-organic frameworks (COFs) can replace traditional sorbents for adsorption-based cooling. In tests mimicking standard operating conditions for industry, the imine-based COF TpPa-1 exhibits a regeneration temperature below 65 °C and a cooling coefficient of performance of 0.77 - values which are comparable to those reported for the best metal-organic framework sorbents described to date. Moreover, TpPa-1 exhibits a photothermal effect and can be regenerated by visible light, thereby opening the possibility for its use in solar-driven cooling

The photothermal effect in MOFs : covalent post-synthetic modification of MOFs mediated by UV-Vis light under solvent-free conditions

Here, we report the covalent post-synthetic modification (CPSM) of MOFs using the photothermal effect. Specifically, we subjected mixtures of a photothermally active MOF and another reagent to irradiation with a UV-Vis lamp. This caused the MOF to heat up, which in turn caused the other reagent to melt and subsequently react with the functional groups on the walls of the MOF pores. We have exploited this dual function of MOFs as both heater and host for CPSMs to achieve rapid formation of amides from the reaction of representative MOFs (UiO-66-NH or MIL-101-NH-(Al)) with anhydrides under solvent-free conditions. In addition, this approach enables more complex CPSMs in MOFs such as the formation of amides in UiO-66-NH by using an aldehyde through a cascade reaction

Structural dynamics and catalytic properties of a multimodular xanthanase

The precise catalytic strategies used for the breakdown of the complex bacterial polysaccharide xanthan, an increasingly frequent component of processed human foodstuffs, have remained a mystery. Here, we present characterization of an endo-xanthanase from Paenibacillus nanensis. We show that it is a CAZy family 9 glycoside hydrolase (GH9) responsible for the hydrolysis of the xanthan backbone capable of generating tetrameric xanthan oligosaccharides from polysaccharide lyase family 8 (PL8) xanthan lyase-treated xanthan. Three-dimensional structure determination reveals a complex multimodular enzyme in which a catalytic (α/α) 6 barrel is flanked by an N-terminal "immunoglobulin-like" (Ig-like) domain (frequently found in GH9 enzymes) and by four additional C-terminal all β-sheet domains that have very few homologues in sequence databases and at least one of which functions as a new xanthan-binding domain, now termed CBM84. The solution-phase conformation and dynamics of the enzyme in the native calcium-bound state and in the absence of calcium were probed experimentally by hydrogen/deuterium exchange mass spectrometry. Measured conformational dynamics were used to guide the protein engineering of enzyme variants with increased stability in the absence of calcium; a property of interest for the potential use of the enzyme in cleaning detergents. The ability of hydrogen/deuterium exchange mass spectrometry to pinpoint dynamic regions of a protein under stress (e.g., removal of calcium ions) makes this technology a strong tool for improving protein catalyst properties by informed engineering

The photothermal effect in MOFs : covalent post-synthetic modification of MOFs mediated by UV-Vis light under solvent-free conditions

Here, we report the covalent post-synthetic modification (CPSM) of MOFs using the photothermal effect. Specifically, we subjected mixtures of a photothermally active MOF and another reagent to irradiation with a UV-Vis lamp. This caused the MOF to heat up, which in turn caused the other reagent to melt and subsequently react with the functional groups on the walls of the MOF pores. We have exploited this dual function of MOFs as both heater and host for CPSMs to achieve rapid formation of amides from the reaction of representative MOFs (UiO-66-NH or MIL-101-NH-(Al)) with anhydrides under solvent-free conditions. In addition, this approach enables more complex CPSMs in MOFs such as the formation of amides in UiO-66-NH by using an aldehyde through a cascade reaction