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Consideration of the water-energy-food nexus is critical to sustainable development, as 18 demand continues to grow along with global population growth. Cost-effective, 19 sustainable technologies to clean water of toxic contaminants are needed. Oxyanions 20 comprise one common class of water contaminants, with many species carrying 21 significant human health risks. The United States Environmental Protection Agency (US 22 EPA) regulates the concentration of oxyanion contaminants in drinking water via the 23 National Primary Drinking Water Regulations (NPDWR). Degrading oxyanions into 24 innocuous compounds through catalytic chemistry is a well-studied approach that does 25 not generate additional waste, which is a significant advantage over adsorption and 26 separation methods. Noble metal nanostructures, e.g., Au, Pd and Pt, are particularly 27 opportunities for metal nanostructures to contribute to improved quality and sustainability 33 of water resources.

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Luminescent gold nanoclusters (Au NCs) are a promising probe material for selective chemical sensing. However, low luminescent intensity and an incomplete understanding of the mechanistic origin of the luminescence limit their practical implementation. We induced glutathione-capped Au NCs to aggregate within silica-coated microcapsular structures using polymer−salt aggregate self-assembly chemistry. The encapsulated NCs have a 5× luminescence enhancement compared to free Au NCs and can detect Cr(VI) at concentrations as low as 6 ppb (=0.12 μM CrO 4 2− ) through luminescence quenching, compared to free Au NCs, which have a limit of detection (LOD) of 52 ppb (=1 μM CrO 4 2− ). The LOD is 16× lower than the United States Environmental Protection Agency maximum contaminant level for total chromium (Cr(III) + Cr(VI), 100 ppb) in drinking water. No pH adjustment is needed using the encapsulated Au NCs, unlike the case for free Au NCs. The luminescent microcapsule material can sense Cr(VI) in simulated drinking water with a ∼20−30 ppb LOD, serving as a possible basis for a practical Cr(VI) sensor.

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The combination of Na2SO4/H2SO4 increases levoglucosan (LGA) yield from glucose pyrolysis from 6% to as high as 40%, as a result of sodium suppressing the opening of the glucose ring.

Produced waters from hydraulic fracturing (HFPW) operations greatly challenge traditional water treatment technologies due to the high concentrations of total dissolved solids (TDS), highly complex and variable water matrices, and significant residual hydrocarbon content. We recently reported the unusual ability of a PdAu catalyst to degrade phenol in simulated HFPW at room temperature by generating H 2 O 2 in situ from formic acid and air. Phenol removal occurred at TDS levels as high as ∼10 000 ppm (ionic strength I = 0.3 M), but the catalytic reaction required pH < 4 to proceed. Here, we find that PdAu, Pd, and Au degraded phenol in the pH 5−8 range by using hydroxylamine as the hydrogen source in place of formic acid. Pd exhibited the highest activity, and Au the least. Activity of the monometallic catalysts decreased >70% as TDS increased from 0 to ∼100 000 ppm (I = 3 M), whereas the PdAu was comparatively less affected (∼50% activity decrease). All catalysts remained active at TDS levels as high as 100 000 ppm. The majority of the hydroxylamine formed N 2 , however this reaction generated additional nitrite/nitrate anion byproducts with nitrogen selectivities ranging from 0.5% to 11.5%, depending on the catalyst identity and reaction salinity. To demonstrate one possible flow treatment process concept, we constructed and tested a recirculating trickle bed reactor that removed 28% phenol from simulated HFPW over 48 h. These results show the potential of oxidation catalysis as a treatment approach for produced water and other high-salinity industrial wastewaters.