A Super-Hygroscopic Solar-Regenerated Alginate-Based Composite for Atmospheric Water Harvesting.

Global water scarcity is leading to increasingly tense competition across populations. In order to complement the largely fast-depleting fresh water sources and mitigate the challenges generated by brine discharge from desalination, atmospheric water harvesting (AWH) has emerged to support long-term water supply. This work presents a novel alginate-based hybrid material comprised of porous silico-aluminophosphate-34 (SAPO-34) as fast-transport channel medium as well as hydrophilicity and stability enhancer, and graphene-based sheets as light absorber for solar-enabled evaporation, both optimally incorporated in an alginate matrix, resulting in a composite sorbent capable of harvesting water from the atmosphere with a record intake of up to 6.85 gw gs -1. Natural sunlight is solely used to enable desorption achieving increase of the temperature of the developed network up to 60 °C and resulting in release of the sorbed water, with impurities content well below the World Health Organization (WHO) upper limits. After 30 cycles of sorption and desorption, the composite hydrogel displayed unchanged water uptake and stability. This work provides an impactful perspective toward sustainable generation of water from humidity without external energy consumption supporting the emergence of alternative water production solutions.

Phthalocyanine-Functionalized Magnetic Silica Nanoparticles as Anion Chemosensors.

Anionic species are one of the most common pollutants in residual and freshwaters. The presence of anthropogenic anions in water drastically increases the toxicity to living beings. Here, we report the preparation of a new optical active material based on tri(tosylamino)phthalocyanines grafted to ferromagnetic silica nanoparticles for anion detection and removal. The new unsymmetrical phthalocyanines (Pcs) proved to be excellent chemosensors for several anions (AcO-, Br-, Cl-, CN-, F-, H2PO4-, HSO4-, NO2-, NO3-, and OH-) in dimethyl sulfoxide (DMSO). Furthermore, the Pcs were grafted onto magnetic nanoparticles. The resulting novel hybrid material showed selectivity and sensitivity towards CN-, F-, and OH- anions in DMSO with limit of detection (LoD) of ≈4.0 µM. In water, the new hybrid chemosensor demonstrated selectivity and sensitivity for CN- and OH- anions with LoD of ≈0.2 µM. The new hybrids are easily recovered using a magnet, allowing recyclability and reusability, after acidic treatment, without losing the sensing proprieties.

A Convenient Synthesis of Pentaporphyrins and Supramolecular Complexes with a Fulleropyrrolidine.

A simple and straightforward synthesis of diporphyrins and pentaporphyrins is reported here. The supramolecular interactions of the new porphyrin derivatives with C60 and PyC60 (a pyridyl [60]fulleropyrrolidine) were evaluated by absorption and fluorescence titrations in toluene. While no measurable modifications of the absorption and fluorescence spectra were observed upon addition of C60 to the porphyrin derivatives, the addition of PyC60 to the corresponding mono-Zn(II) porphyrins resulted in the formation of Zn(porphyrin)-PyC60 coordination complexes and the binding constants were calculated. Results show that the four free-base porphyrin units in pentaporphyrin 6 have a significant contribution in the stabilization of the 6-PyC60 complex. The crystal and molecular features of the pentaporphyrin Zn5 were unveiled using single-crystal X-ray diffraction studies.

Unprecedented Double aza-Michael Addition within a Sapphyrin Core.

A novel sapphyrin derivative was obtained from the reaction between a free-base sapphyrin and dimethyl acetylenedicarboxylate (DMAD). The formation of the new compound involved a double aza-Michael addition of two pyrrolic NH groups to a DMAD molecule, with the formation of a disubstituted ethano bridge. The NMR spectral data reveal a product with an unsymmetrical structure; DFT calculations provided support for a structure in which the ethano bridge links two adjacent pyrrole units. The present study provides a seemingly unprecedented example of an N,N'-dinucleophile reacting with DMAD to form a heterocyclic compound in which the two N-atoms are linked to the two sp(3) carbon atoms derived from a substituted acetylene.

A Semi-Interpenetrating Network Sorbent of Superior Efficiency for Atmospheric Water Harvesting and Solar-Regenerated Release.

Water is readily available nearly anywhere as vapor. Thus, atmospheric water harvesting (AWH) technologies are seen as a promising solution to support sustainable water production. This work reports a novel semi-interpenetrating network, which integrates poly(pyrrole) doped with a hygroscopic salt and 2D graphene-based nanosheets optimally assembled within an alginate matrix, capable of harvesting water from the atmosphere with a record intake of up to 7.15 gw/gs. Owing to the incorporated graphene nanosheets, natural sunlight was solely used to enable desorption, achieving an increase of the temperature of the developed network of up to 71 °C within 20 min, resulting in a water yield of 3.36 L/kgS in each cycle with quality well within the World Health Organization standard ranges. Notably, after 30 cycles of sorption and desorption, the composite hydrogel displayed unchanged water uptake and stability. This study demonstrates that atmospheric water vapor as a complementary source of water can be harvested sustainably and effectively at a minimal cost and without external energy input.

Seawater Reverse Osmosis Performance Decline Caused by Short-Term Elevated Feed Water Temperature.

The shortage of fresh water resources has made the desalination of seawater a widely adopted technology. Seawater reverse osmosis (SWRO) is the most commonly used method for desalination. The SWRO process is energy-intensive, and most of the energy in SWRO is spent on pressurizing the seawater to overcome the osmotic barrier for producing fresh water. The pressure needed depends on the salinity of the seawater, its temperature, and the membrane surface properties. Membrane compaction occurs in SWRO due to hydraulic pressure application for long-term operations and operating temperature fluctuations due to seasonal seawater changes. This study investigates the effects of short-term feed water temperature increase on the SWRO process in a full-scale pilot with pretreatment and a SWRO installation consisting of a pressure vessel which contains seven industrial-scale 8" diameter spiral wound membrane elements. A SWRO feed water temperature of 40 °C, even for a short period of 7 days, caused a permanent performance decline illustrated by a strong specific energy consumption increase of 7.5%. This study highlights the need for membrane manufacturer data that account for the water temperature effect on membrane performance over a broad temperature range. There is a need to develop new membranes that are more tolerant to temperature fluctuations.

Natural deep eutectic solvents as biofilm structural breakers.

Natural Deep Eutectic Solvents (NADES) are composed of supramolecular interactions of two or more natural compounds, such as organic acids, sugars, and amino acids, and they are being used as a new media alternative to conventional solvents. In this study, a new application of NADES is presented as a possible technology for biofilm structural breaker in complex systems since the current solvents used for biofilm cleaning and extraction of biofilm components use hazardous solutions. The NADES (betaine:urea:water and lactic acid:glucose:water) were analyzed before and after the biofilm treatment by attenuated total reflection Fourier-transform infrared spectroscopy and fluorescence excitation-emission matrix spectroscopy. Our results indicate that the green solvents could solubilize up to ≈70 percent of the main components of the biofilms extracellular matrix. The solubilization of the biomolecules weakened the biofilm structure, which could enhance the biofilm solubilization and removal. The NADES have the potential to be an environment-friendly, green solvent to extract valuable compounds and break the main structure from the biofilm, leading to a greener method for extracellular polymeric substance (EPS) extraction and biofilm treatment in various water treatment systems.

Reply to the 'Comment on "The chemical reactions in electrosprays of water do not always correspond to those at the pristine air-water interface"' by A. J. Colussi and S. Enami, Chem. Sci., 2019, 10, DOI: 10.1039/c9sc00991d.

The air-water interface serves as a crucial site for numerous chemical and physical processes in environmental science and engineering, such as cloud chemistry, ocean-atmosphere exchange, and wastewater treatment. The development of "surface-selective" techniques for probing interfacial properties of water therefore lies at the forefront of research in chemical science. Recently, researchers have adapted electrospray ionization mass spectrometry (ESIMS) to generate microdroplets of water to investigate interfacial phenomena at thermodynamic equilibrium. In contrast, using a broad set of experimental and theoretical techniques, we found that electrosprays of water could facilitate partially hydrated (gas-phase) ions (e.g., H3O+·(H2O)2) to drive/catalyze chemical reactions that are otherwise not possible to accomplish by purely interfacial effects (e.g., enhanced water-hydrophobe surface area) (Chem. Sci., 2019, 10, 2566). Thus, techniques exploiting electrosprays of water cannot be relied upon as generalized surface-selective platforms. Here, we respond to the comments raised by Colussi & Enami (Chem. Sci., 2019, 10, DOI: ; 10.1039/c9sc00991d) on our paper.

The chemical reactions in electrosprays of water do not always correspond to those at the pristine air-water interface.

The recent application of electrosprays to characterize the air-water interface, along with the reports on dramatically accelerated chemical reactions in aqueous electrosprays, have sparked a broad interest. Herein, we report on complementary laboratory and in silico experiments tracking the oligomerization of isoprene, an important biogenic gas, in electrosprays and isoprene-water emulsions to differentiate the contributions of interfacial effects from those of high voltages leading to charge-separation and concentration of reactants in the electrosprays. To this end, we employed electrospray ionization mass spectrometry, proton nuclear magnetic resonance, ab initio calculations and molecular dynamics simulations. We found that the oligomerization of isoprene in aqueous electrosprays involved minimally hydrated and highly reactive hydronium ions. Those conditions, however, are non-existent at pristine air-water interfaces and oil-water emulsions under normal temperature and pressure. Thus, electrosprays should be complemented with surface-specific platforms and theoretical methods to reliably investigate chemistries at the pristine air-water interface.

Analysing sulphate and chloride in mineral drinking water by flow injection analysis with a single acoustic wave sensor.

Sulphate is a very hydrophilic anion, and, therefore, difficult to be selectively determined in aqueous solution with a coated sensor. Zinc(II) 2,3,9,10,16,17,23,24-Octatosylaminophthalocyanine was used for the first time as a sensitive coating. Selectivity to sulphate regarding chloride was not enough to ignore its contribution in mineral waters, and, therefore, an analytical protocol was carefully designed to allow the determination of both anions with this sensor. Results displayed on the label of eight commercial bottles of mineral waters are within the confidence interval of the values obtained with the FIA-sensor system, both for chloride and sulphate. However, results for chloride obtained by titrimetry are, in half of the cases, statistically different from the ones obtained by the sensor, and in 7 out of 8 of them more precise. There is an evidence of a systematic error in the chloride titrimetric analysis, consistent with a small overtaking of the equivalence point. Precision of the results obtained by the titrimetric analysis of sulphate were in 6 out of 8 of the analysis less precise than with the sensor, probably due to losses of the barium sulphate precipitate, which is consistent with the occurrence of lower values.

[28]Hexaphyrin derivatives for anion recognition in organic and aqueous media.

Hexaphyrin-based anion chemosensors are reported for the first time. The meso-hexakis(ethylenediamine)-substituted [28]hexaphyrins 2 and 3 revealed strong affinity for F(-), AcO(-) and H2PO4(-). Adsorption constants in aqueous media were determined on a gold piezoelectric crystal coated with 2 and 3. (1)H NMR titrations and molecular dynamics simulations showed the main interactions between hosts and guests.

New porphyrin derivatives for phosphate anion sensing in both organic and aqueous media.

New porphyrin-based anion receptors have been prepared from meso-tetrakis(pentafluorophenyl)porphyrin () and diamine derivatives. These receptors (compounds ) interact preferentially with phosphate anions both in organic solutions and in basic aqueous media when coated on gold piezoelectric quartz crystals. A single crystal X-ray structure of the bis-HF complex of a imine derivative of was obtained; it serves to highlight the main interactions between the anion and cation receptors in the solid state.