Microwave Heating of Superparamagnetic Iron-Oxide Nanoparticles Toward Environmental Hyperthermia-Based Applications.

This article reports the effect of spherical particle size (4-30 nm) on magnetic properties and microwave (MW) reactivity of superparamagnetic iron oxide nanoparticles (SPIONs) toward environmental hyperthermia-based applications. For this, silica-coated, single domain iron oxide nanoparticles (IONPs@silica) were precisely synthesized via thermal decomposition and subsequently coated by a reverse microemulsion. Transmission electron microscopy and X-ray diffraction confirmed the formation of spherical, monodisperse, single continuous layer silica-coated magnetite nanoparticles.

Toward Continuous, Oriented Covalent Organic Framework Membranes for Precise Molecular Separations.

The goal of achieving energy-efficient, precise molecular separations has motivated interest in developing and employing porous crystalline frameworks as membrane materials. Covalent organic frameworks (COFs) are ordered crystalline matrices composed of covalently bonded organic monomers and are synthesized via reversible reticular chemistry. COFs possess high porosity, structural tunability, and chemical and thermal stability, making them ideally suited for emerging, high-value membrane separation processes, such as ion separations, organic solvent nanofiltration, and gas separations.

Secondary Mobility of Arsenic Due to In Situ-Generated Iron-Arsenic Colloids upon Iron Oxide Amendments.

Applying iron (Fe) amendments to arsenic (As)-contaminated groundwater to form As-laden Fe precipitates represents a promising in situ remediation approach. However, less is known about the secondary risk of As mobilization due to formation of Fe-As colloids released from these precipitates. Here, we systematically explored the nanoscale formation, composition, and stability of Fe-As colloids in high-As contaminated groundwater following the addition of Fe salts under oxic conditions.

High-Concentration Multibranched Gold Nanoparticle Synthesis via Controllable Seeding.

Engineering gold nanostructures with a high number of sharp branches allows harvesting near-infrared light-induced localized surface plasmon resonance (LSPR) effects in which free electrons are brought into oscillation with exceptional electromagnetic field enhancement at the branch tips of these particles. These tip effects make such particles promising candidates for biological, catalytic, and spectroscopic applications. In this work, a scale-up process for highly multibranched gold nanoparticles at high concentrations (2.

Remediation of groundwater contaminated with perfluoroalkyl acids and chlorinated ethenes using a microbial reductive dechlorination and sorptive material treatment train.

Groundwater contaminated by mixtures of perfluoroalkyl acids (PFAAs) and chlorinated ethenes (CEs) pose a significant remediation challenge due to the distinct characteristics of these two contaminant types. In situ adsorption barriers have been demonstrated as a promising remediation strategy for PFAA-contaminated groundwater plumes. However, most previous studies were carried out with only a single PFAA, and our understanding of the retention of comingled contaminant plumes, including multiple PFAAs and CEs in such barriers, remains limited.

Effective electrochemical trichloroethylene removal from water enabled by selective molecular catalysis.

Electrochemistry can provide a viable and sustainable way to treat water polluted by chlorinated volatile organic compounds. However, the removal and valorization of trichloroethylene (TCE) remains as a challenge due to the lack of suitable electrocatalysts with high selectivity and activity. We herein present a catalyst, comprising cobalt phthalocyanine (CoPc) molecules assembled onto multiwalled carbon nanotubes (CNTs), that can electrochemically decompose aqueously dissolved TCE into ethylene and chloride ions at record high rates with close to 100% Faradaic efficiency.

Microwave-enhanced catalytic degradation of organic compounds with silica-coated iron oxide nanocrystals via fenton-like reaction pathway.

Microwave (MW)-enhanced catalytic oxidation processes are emerging and effective techniques for the degradation of organic compounds in water and wastewater treatment processes. In this study, through applied MW irradiation, monodisperse, superparamagnetic iron oxide nanocrystals (IONCs) with thin, amorphous silica coatings are demonstrated to rapidly catalyze the degradation of organic compounds in water through a thermally enhanced, Fenton-type process. For this, we precisely synthesize amorphous silica-coated various metal oxide (single domain) nanocrystals, and then evaluate the degradation of methyl orange (MO) and benzoic acid (BA), chosen as model organic molecules.

Tuning Metal-Organic Framework Linker Chemistry for Transition Metal Ion Separations.

The pressing demand for critical metals necessitates the development of advanced ion separation technologies for circular resource economies. To separate transition metal ions, which exhibit near-identical chemical properties, adsorbents and membranes must be designed with ultraselective chemistries. We leverage the customizability of metal-organic frameworks (MOFs) to systematically study the role of material chemistry in sorption and selectivity of Co, Ni, and Cu.

Multiplexable and Scalable Aqueous Synthesis Platform for Oleate-Based, Bilayer-Coated Gold Nanoparticles.

Despite gold-based nanomaterials having a unique role in nanomedicine, among other fields, synthesis limitations relating to reaction scale-up and control result in prohibitively high gold nanoparticle costs. In this work, a new preparation procedure for lipid bilayer-coated gold nanoparticles in water is presented, using sodium oleate as reductant and capping agent. The seed-free synthesis not only allows for size precision (8-30 nm) but also remarkable particle concentration (10 mm Au).

Total organic carbon measurements reveal major gaps in petrochemical emissions reporting.

Anthropogenic organic carbon emissions reporting has been largely limited to subsets of chemically speciated volatile organic compounds. However, new aircraft-based measurements revealed total gas-phase organic carbon emissions that exceed oil sands industry-reported values by 1900% to over 6300%, the bulk of which was due to unaccounted-for intermediate-volatility and semivolatile organic compounds. Measured facility-wide emissions represented approximately 1% of extracted petroleum, resulting in total organic carbon emissions equivalent to that from all other sources across Canada combined.

Harnessing the potential of in-situ, electrically generated microbubbles via nickel foam for enhanced, low energy membrane fouling control.

For membrane-based, water treatment technologies, fouling remains a significant challenge for pressure-driven processes. While many antifouling strategies have been proposed, there remains significant room for improved efficiency. Direct application of microbubbles (MBs) at a membrane surface offers a promising approach for managing interfacial fouling through continuous physical interaction(s).

Nanobubble Reactivity: Evaluating Hydroxyl Radical Generation (or Lack Thereof) under Ambient Conditions.

Nanobubble (NB) generation of reactive oxygen species (ROS), especially hydroxyl radical (OH), has been controversial. In this work, we extensively characterize NBs in solution, with a focus on ROS generation (as OH), through a number of methods including degradation of OH-specific target compounds, electron paramagnetic resonance (EPR), and a fluorescence-based indicator. Generated NBs exhibit consistent physical characteristics (size, surface potential, and concentration) when compared with previous studies.

Superparamagnetic Iron Oxide Nanoparticles as Additives for Microwave-Based Sludge Prehydrolysis: A Perspective.

Wastewater treatment plants are critical for environmental pollution control. The role that they play in protecting the environment and public health is unquestionable; however, they produce massive quantities of excess sludge as a byproduct. One pragmatic approach to utilizing excess sludge is generating methane via anaerobic digestion.

Microbial Reductive Dechlorination by a Commercially Available Dechlorinating Consortium Is Not Inhibited by Perfluoroalkyl Acids (PFAAs) at Field-Relevant Concentrations.

Perfluoroalkyl acids (PFAAs) have been shown to inhibit biodegradation (i.e., organohalide respiration) of chlorinated ethenes.

Trace analysis of per- and polyfluorinated alkyl substances (PFAS) in dried blood spots - Demonstration of reproducibility and comparability to venous blood samples.

Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals that have been widely used in consumer, personal care, and household products for their stain- and water-repellent properties. PFAS exposure has been linked to various adverse health outcomes. Such exposure has commonly been evaluated in venous blood samples.

In-situ sequestration of perfluoroalkyl substances using polymer-stabilized ion exchange resin.

Remediation of groundwater impacted by per- and polyfluoroalkyl substances (PFAS) is challenging due to the strength of the carbon-fluorine bond and the need to achieve nanogram per liter drinking water targets. Previous studies have shown that ion exchange resins can serve as effective sorbents for the removal of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) in conventional water treatment systems. The objectives of this study were to evaluate the in situ delivery and PFAS sorption capacity of a polymer-stabilized ion exchange resin (S-IXR) consisting of Amberlite® IRA910 beads and Pluronic® F-127 in a quartz sand.

Photoactive Polyethylenimine-Coated Graphene Oxide Composites for Enhanced Cr(VI) Reduction and Recovery.

The application of positively charged polymers is a common treatment strategy for the sorption and separation of dissolved hexavalent chromium Cr(VI). In particular, polyethylenimine (PEI) has been demonstrated as an effective polymer for Cr treatment due to abundant amine groups and cost-effectiveness. However, PEI as a photoactive polymer has not been previously explored for Cr treatment.

Yale School of Public Health Symposium: An overview of the challenges and opportunities associated with per- and polyfluoroalkyl substances (PFAS).

On December 13, 2019, the Yale School of Public Health hosted a symposium titled "Per- and Polyfluoroalkyl Substances (PFAS): Challenges and Opportunities" in New Haven, Connecticut. The meeting focused on the current state of the science on these chemicals, highlighted the challenges unique to PFAS, and explored promising opportunities for addressing them. It brought together participants from Yale University, the National Institute of Environmental Health Sciences, the University of Massachusetts Amherst, the University of Connecticut, the Connecticut Agricultural Experiment Station, the Connecticut Departments of Public Health and Energy and Environmental Protection, and the public and private sectors.

Pharmacological Comparison of Mitragynine and 7-Hydroxymitragynine: In Vitro Affinity and Efficacy for -Opioid Receptor and Opioid-Like Behavioral Effects in Rats.

Relationships between -opioid receptor (MOR) efficacy and effects of mitragynine and 7-hydroxymitragynine are not fully established. We assessed in vitro binding affinity and efficacy and discriminative stimulus effects together with antinociception in rats. The binding affinities of mitragynine and 7-hydroxymitragynine at MOR (K values 77.

A graphene oxide Cookbook: Exploring chemical and colloidal properties as a function of synthesis parameters.

Herein, we describe the synthesis of graphene oxide (GO) over a large range of conditions, exploring the effects of reaction temperature, reaction time, oxidant ratio, and sonication time on the chemical and colloidal properties of the product. As a function of reaction parameters, modified from Hummers' method, GO products were characterized and described via a suite of spectroscopic, structural, and morphological techniques, including TEM, UV-vis spectroscopy, XPS, Raman spectroscopy, FTIR, and DLS. Average carbon oxidation state and the yield (upon sonication) were chosen as the two criteria to evaluate synthesized GO materials.

Intrapore energy barriers govern ion transport and selectivity of desalination membranes.

State-of-the-art desalination membranes exhibit high water-salt selectivity, but their ability to discriminate between ions is limited. Elucidating the fundamental mechanisms underlying ion transport and selectivity in subnanometer pores is therefore imperative for the development of ion-selective membranes. Here, we compare the overall energy barrier for salt transport and energy barriers for individual ion transport, showing that cations and anions traverse the membrane pore in an independent manner.

Graphene oxide/mussel foot protein composites for high-strength and ultra-tough thin films.

Graphene oxide (GO)-based composite materials have become widely popular in many applications due to the attractive properties of GO, such as high strength and high electrical conductivity at the nanoscale. Most current GO composites use organic polymer as the matrix material and thus, their synthesis suffers from the use of organic solvents or surfactants, which raise environmental and energy-consumption concerns. Inspired by mussel foot proteins (Mfp) secreted by the saltwater mussel, Mytilus galloprovincialis and by recent advances in microbial protein production, we developed an aqueous-based green synthesis strategy for preparing GO/Mfp film composites.

Surface-Engineered Nanomaterials in Water: Understanding Critical Dynamics of Soft Organic Coatings and Relative Aggregation Density.

Inorganic-organic nanocomposites, typically as an inorganic core with surface organic coating(s), have received interest as potential platform materials for sensor, catalyst, sorbent, and environmental applications, among others. Here, we describe the critical role of organic surface coatings with regard to the colloidal stability of engineered manganese oxide nanoparticles (MnO NPs). Specifically, we prepared libraries of monodisperse MnO NPs with a serial selection of surface coatings (stearic acid (SA), oleic acid (OA), poly(maleic anhydride--1-octadecene) (PMAO), linear polyethyleneimine (LPEI), and multibranched polyethyleneimine (BPEI)), which were chosen based on comparable structure(s) and functional group(s).

Delineating the Relationship between Nanoparticle Attachment Efficiency and Fluid Flow Velocity.

The ability to fundamentally describe nanoparticle (NP) transport in the subsurface underpins environmental risk assessment and successful material applications, including advanced remediation and sensing technologies. Despite considerable progress, our understanding of NP deposition behavior remains incomplete as there are conflicting reports regarding the effect of fluid flow velocity on attachment efficiency. To directly address this and more accurately describe NP attachment behavior, we have developed a novel protocol using a quartz crystal microbalance with dissipation monitoring (QCM-D) to separate and individually observe deposition mechanisms (diffusion and sedimentation), providing in situ, real-time information about particle diffusion (from the bulk liquid to solid surface).