Electrochemical water treatment is increasingly popular for a variety of applications, including resource recovery and advanced oxidation processes. In complex environmental matrices, electro-oxidative processes are known to form hazardous byproducts. This study identifies a new pathway for N-nitrosodimethylamine (NDMA) formation via nitrite electro-oxidation in spiked synthetic and natural electrolytes. In a novel flow-through electrochemical cell, NDMA formation was observed from 1 mg/L N nitrite and 100 μg/L dimethylamine, yielding 169-553 ng/L NDMA in a 1 mM Na2SO4 electrolyte and 189-715 ng/L NDMA in a drinking water treatment plant matrix across various cell potentials (2-12 V and 2-10 V, respectively), exceeding the resident tap water regional screening level for NDMA (0.11 ng/L) by over 1000-fold. Uniquely, formation exclusively occurred in cathode-to-anode flow. Voltammetric data and mechanistic insights are consistent with a cathodic process increasing downstream pH, consequently facilitating amine deprotonation and enabling its nitrosation via N2O4 generated from nitrite oxidation. Generally, nitrite or chloride oxidation activity monitoring (via chlorine residual measurement) was not predictive of nitrosamine yield, and direct measurement of nitrosamines using sensitive analytical techniques (limit of quantification: 55 ng/L) was necessary. This work highlights the understudied formation potential for toxic nitrogenous byproducts in emerging electrochemical treatment technologies, particularly in nitrate recovery contexts.

Intrinsic water evaporation demands a high energy input, which limits the efficacy of conventional interfacial solar evaporators. Here, we propose a nanoconfinement strategy altering inherent properties of water for solar-driven water evaporation using a highly uniform composite of vertically aligned Janus carbon nanotubes (CNTs). The water evaporation from the CNT shows the unexpected diameter-dependent evaporation rate, increasing abnormally with decreasing nanochannel diameter. The evaporation rate of CNT 10 @AAO evaporator thermodynamically exceeds the theoretical limit (1.47 kg m −2 hour −1 under one sun). A hybrid experimental, theoretical, and molecular simulation approach provided fundamental evidence of different nanoconfined water properties. The decreased number of H-bonds and lower interaction energy barrier of water molecules within CNT and formed water clusters may be one of the reasons for the less evaporative energy activating rapid nanoconfined water vaporization.

Demulsification technology for separation of oil-water (O/W) emulsions, especially those stabilized by surfactants, is urgently needed yet remains highly challenging due to their inherent stability characteristics. Electrocoalescence has emerged as a promising solution owing to its simplicity, efficacy, and versatility, yet hindered by substantial energy consumption (e.g., >50 kWh/m(3)) along with undesirable Faradic reactions. Herein, we propose an innovative electric demulsification technology that leverages conductive membrane microchannels to confine oil droplets from the oil-water emulsion for achieving high energy-efficient coalescence of oil droplets. The proposed system reduces the required voltage down to 12 V, 2 orders of magnitude lower than that of conventional electrocoalescence systems, while achieving a similar separation efficacy of 91.4 +/- 3.0% at a low energy consumption (3 kWh/m(3)) and an ultrahigh permeability >3000 L/(m(2)hbar). In situ fluorescence microscopy combined with COMSOL simulations provided insight into the fundamental mechanistic steps of an electric demulsification process confined to membrane microchannels: (1) rapid electric-field redistribution of oil droplet surfactant molecules, (2) enhanced collision probability due to confined oil droplet concentration under dielectrophoretic forces, and (3) increased collision efficacy facilitated by the membrane pore structure. This strategy may revolutionize the next generation of demulsification and oil-water separation innovations.

This work describes the fabrication of a novel electroconductive membrane made of Ti3C2Tx (MXene) nanosheet coating through a one-step pressure-assisted technique. Ti3C2-MXene is firmly attached over a polyamide-imide (PAI) microfilter by employing a binder composed of carboxymethyl cellulose (CMC)/glutaraldehyde (GA). Through coating a proper amount of multilayer Ti3C2-MXene, the electrical conductivity of 174 +/- 0.16 S m(-1) is achieved. The rejection rates of reactive red 120 (RR120), reactive black (RB), and methyl orange (MO) by the pristine PAI membrane are 45.2%, 40.81%, and 33.65%, respectively. However, rejection rates significantly improve with the Ti3C2 MXene coating to over 99.71%, 97.95%, and 68.91% for RR120, RB, and MO. Applying a 4 V cathodic potential resulted in a flux recovery ratio (FRR) of 99.83% and a flux decline rate (FDR) of less than 1% during humic acid (HA) filtration. Without applying voltage, the MXene-coated membrane shows an FRR and FDR of 92.51% and 45.56%, respectively. Surface energy analysis reveals strong repulsive interactions between foulants and the membrane surface. Moreover, the surface free energy indicates that foulants such as sodium alginate (SA) and bovine serum albumin (BSA) exhibit stronger adhesion to the membrane than HA, consistent with the fouling experiment results.

Adsorption is a classical physicochemical process, widely used in heterogeneous catalysis, chemical engineering, and environmental science. Regenerating the exhausted adsorbents or reversible desorption is vital to achieving sustainable adsorption techniques, while the common chemical/thermal regeneration is energy-intensive and environmentally unfriendly. Given that the adsorbents' surface physicochemical properties like surface charge and electronic structures, significantly affect adsorption capacity and kinetics, which offers opportunities for green desorption by tailoring surface chemical/electronic features. Since a certain adsorbate possesses specific adsorption energy on adsorbents, an electro-desorption idea is therefore proposed to electrically control the (sequential) release of aqueous substances by regulating the interfacial adsorption interaction above the corresponding threshold interfacial potential. Herein, as a proof-of-concept design, a sub-millimeter-sized carbon nanotube-reinforced conductive resin composite adsorbent with high conductivity and mechanical strength is developed, which demonstrates a high electro-desorption efficiency toward benzoic acid (94.1%; 3 V negative bias) and well-controlled electro-desorption kinetics by regulating the surface polarization. Using benzoic acid and terephthalic acid as a model of organic mixtures, the adsorbent exhibits an efficient bias-dependent sequential electro-desorption capability in separating mixtures. This work provides a promising efficient solution for green and efficient desorption/regeneration and a pioneering electrically-driven strategy toward aqueous mixture separation. Industrial regeneration often requires harsh elution, resulting in significant solvent/energy consumption and secondary pollution. Here, a proof-of-concept electro-desorption idea is reported using a conductive composite absorbent, achieving high desorption efficiency and even sequential separation of a model mixture under a small bias. This pioneering electrically driven approach toward mixture separation or adsorbate extraction holds significant promise for sustainable industrial practices. image

Drinking water contamination by per- and polyfluoroalkyl substances (PFAS) is widespread near more than 300 United States (U.S.) military bases that used aqueous film-forming foams (AFFF) for fire training and firefighting activities. Much of the PFAS at these sites consist of precursors that can transform into terminal compounds of known health concern but are omitted from standard analytical methods. Here, we estimate the expected duration and contribution of precursor biotransformation to groundwater PFAS contamination at an AFFF-contaminated military base on Cape Cod, Massachusetts, United States, by optimizing a geochemical box model using measured PFAS concentrations from a multidecadal time series of groundwater and a soil survey in the source zone. A toolbox of analytical techniques used to reconstruct the mass budget of PFAS showed that precursors accounted for 46 ± 8% of the extractable organofluorine (a proxy for total PFAS) across years. Terminal PFAS still exceed regulatory limits by 2000-fold decades after AFFF use ceased. Measurements and numerical modeling show that sulfonamido precursors are retained in the vadose zone and their slow biotransformation into perfluoroalkyl sulfonates (half-life > 66 yr) sustains groundwater concentrations of perfluorobutane sulfonate (PFBS) and perfluorohexane sulfonate (PFHxS). The estimated PFAS reservoir in the vadose zone and modeled flux into groundwater suggest PFAS contamination above regulatory guidelines will persist for centuries without remediation.

This study examined adult age differences in identification accuracy, confidence, and verbal recall of crime films. A total of 120 Ss in 3 adult age groups watched 2 crime films that contained characters varying in role and visibility. Results suggested a modest negative relationship between age and identification accuracy but no age differences in recall of main points or details. Education and self-reported health positively predicted verbal recall, but higher education was associated with lower identification accuracy. No age differences were found in confidence or in the relationship between confidence and accuracy.

Hydrogen peroxide (H2O2), as a critical green chemical, has received immense attention in energy and environmental fields. The ability to produce H2O2 in earth-abundant water without relying on low solubility oxygen would be a sustainable and potentially economic process, applicable even to anaerobic microenvironments, such as groundwater treatment. However, the direct water to H2O2 process is currently hindered by low selectivity and low production rates. Herein, we report that poly(tetrafluoroethylene) (PTFE), a commonly used inert polymer, can act as an efficient triboelectric catalyst for H2O2 generation. For example, a high H2O2 production rate of 24.8 mmol g(cat)(-1) h(-1) at a dosage of 0.01 g/L PTFE was achieved under the condition of pure water, ambient atmosphere, and no sacrificial agents, which exceeds the performance of state-of-the-art aqueous H2O2 powder catalysts. Electron spin resonance and isotope experiments provide strong evidence that water-PTFE tribocatalysis can directly oxidize water to produce H2O2 under both anaerobic and aerobic conditions, albeit with different synthetic pathways. This study demonstrates a potential strategy for green and effective tribocatalytic H2O2 production that may be particularly useful toward environmental applications.

Fine-tuning the geometric and electronic structure of catalytic metal centers via N-coordination engineering offers an effective design for the electrocatalytic transformation of O2 to singlet oxygen (1O2). Herein, we develop a general coordination modulation strategy to synthesize fluidic single-atom electrodes for selective electrocatalytic activation of O2 to 1O2. Using a single Cr atom system as an example, >98% 1O2 selectivity can be achieved from electrocatalytic O2 activation due to the subtle engineering of Cr-N4 sites. Both theoretical simulations and experimental results determined that "end-on" adsorption of O2 onto the Cr-N4 sites lowers the overall activation energy barrier of O2 and promotes the breakage of Cr-OOH bonds to form •OOH intermediates. In addition, the flow-through configuration (k = 0.097 min-1) endowed convection-enhanced mass transport and improved charge transfer imparted by spatial confinement within the lamellar electrode structure compared to that of batch reactor (k = 0.019 min-1). In a practical demonstration, the Cr-N4/MXene electrocatalytic system exhibits a high selectivity toward electron-rich micropollutants (e.g., sulfamethoxazole, bisphenol A, and sulfadimidine). The flow-through design of the fluidic electrode achieves a synergy with the molecular microenvironment that enables selective electrocatalytic 1O2 generation, which could be used in numerous ways, including the treatment of environmental pollution.

Effective and stable antibiofouling surfaces and interfaces have long been of research interest. In this study, we designed, fabricated, and evaluated a surface coated with insulated interlaced electrodes for bacterial fouling reduction. The electrodes were printed Ag filaments of 100 μm width and 400 μm spacing over an area of 2 × 2 cm2. The insulating Ag electrode coating material was polydimethylsiloxane (PDMS) or thermoplastic polyurethane (TPU) with a thickness of 10 to 40 μm. To evaluate the antibiofouling potential, E. coli inactivation after 2 min contact with the electrified surface and P. fluorescens detachment after 15 and 40 h growth were examined. The extent of bacterial inactivation was related to the insulating material, coating thickness, and applied voltage (magnitude and AC vs DC). A high bacterial inactivation (>98%) was achieved after only 2 min of treatment at 50 V AC and 10 kHz using a 10 μm TPU coating. P. fluorescens detachment after 15 and 40 h incubation in the absence of applied potential was completed with simultaneous cross-flow rinsing and AC application. Higher AC voltages and longer cross-flow rinsing times resulted in greater bacterial detachment with bacterial coverage able to be reduced to <1% after only 2 min of rinsing at 50 V AC and 10 kHz. Theoretical electric field analysis indicated that at 10 V the field strength penetrating the aqueous solution is nonuniform (∼16,000-20,000 V m-1 for the 20 μm TPU) and suggests that dielectrophoresis plays a key role in bacterial detachment. The bacterial inactivation and detachment trends observed in this study indicate that this technique has merit for future antibiofouling surface development.

Magnetic stir bars are routinely used by most of researchers in the fields of chemistry, biology and environment etc. An incredible phenomenon, in which the magnetic stirring increased reaction rate by tens of times under ultrasound irradiation, impelled us to explore roles of magnetic stirring. Unexpectedly, the thimbleful nano PTFE particles, from shell of magnetic stir bar, were exfoliated during magnetic stirring and account for ultrahigh tribocatalytic and piezocatalytic activities under ultrasonic irradiation. Reactive oxygen species (ROS), such as hydroxyl radical (OH), superoxide radicals (O2-) and singlet oxygen (1O2) were generated in the present of PTFE under ultrasound irradiation, which is desired in the pollution control. The newly discovered PTFE activity, against the conventional wisdom that PTFE is inert, which also reminds the researchers that the trace amount of PTFE ground during magnetic stirring may inadvertently botch our experiments and introduce false positive results, especially involving routine magnetic stirring and ultrasound irradiation operation in laboratory. In addition, the safety and inertness of PTFE may require further review in PTFE-based commercial, industrial and biomedical settings.

Pressure-driven membranes is a widely used separation technology in a range of industries, such as water purification, bioprocessing, food processing and chemical production 1 , 2 . Despite their numerous advantages, such as modular design and minimal footprint, inevitable membrane fouling is the key challenge in most practical applications 3 . Fouling limits membrane performance by reducing permeate flux or increasing pressure requirements, which results in higher energetic operation and maintenance costs 4 – 7 . Here we report a hydraulic-pressure-responsive membrane (PiezoMem) to transform pressure pulses into electroactive responses for in situ self-cleaning. A transient hydraulic pressure fluctuation across the membrane results in generation of current pulses and rapid voltage oscillations (peak, +5.0/−3.2 V) capable of foulant degradation and repulsion without the need for supplementary chemical cleaning agents, secondary waste disposal or further external stimuli 3 , 8 – 13 . PiezoMem showed broad-spectrum antifouling action towards a range of membrane foulants, including organic molecules, oil droplets, proteins, bacteria and inorganic colloids, through reactive oxygen species (ROS) production and dielectrophoretic repulsion.

The mass production of graphene oxide (GO) unavoidably elevates the chance of human exposure, as well as the possibility of release into the environment with high stability, raising public concern as to its potential toxicological risks and the implications for humans and ecosystems. Therefore, a thorough assessment of GO toxicity, including its potential reliance on key physicochemical factors, which is lacking in the literature, is of high significance and importance. In this study, GO toxicity, and its dependence on oxidation level, elemental composition, and size, were comprehensively assessed. A newly established quantitative toxicogenomic-based toxicity testing approach, combined with conventional phenotypic bioassays, were employed. The toxicogenomic assay utilized a GFP-fused yeast reporter library covering key cellular toxicity pathways. The results reveal that, indeed, the elemental composition and size do exert impacts on GO toxicity, while the oxidation level exhibits no significant effects. The UV-treated GO, with significantly higher carbon-carbon groups and carboxyl groups, showed a higher toxicity level, especially in the protein and chemical stress categories. With the decrease in size, the toxicity level of the sonicated GOs tended to increase. It is proposed that the covering and subsequent internalization of GO sheets might be the main mode of action in yeast cells.

Fundamental design parameters for future development of novel antiviral nanomaterials.

Aqueous PFAS concentrations fluctuate seasonally and precursor concentrations rapidly decline within the surface-water/groundwater boundary, indicating that transport through this boundary can affect spatial and temporal PFAS composition.

The wide application of carbon-based nanomaterials (CNMs) has resulted in the ubiquity of CNMs in the natural environment and they potentially impose adverse consequences on ecosystems and human health. In this study, we comprehensively evaluated and compared potential toxicological effects and mechanisms of seven CNMs in three representative types (carbon blacks, graphene nanoplatelets, and fullerenes), to elucidate the correlation between their physicochemical/structural properties and toxicity. We employed a recently-developed quantitative toxicogenomics-based toxicity testing system with GFP-fused yeast reporter library targeting main cellular stress response pathways, as well as conventional phenotype-based bioassays. The results revealed that DNA damage, oxidative stress, and protein stress were the major mechanisms of action for all the CNMs at sub-cytotoxic concentration levels. The molecular toxicity nature were concentration-dependent, and they exhibited both similarity within the same structural group and distinctiveness among different CNMs, evidencing the structure-driven toxicity of CNMs. The toxic potential based on toxicogenomics molecular endpoints revealed the remarkable impact of size and structure on the toxicity. Furthermore, the phenotypic endpoints derived from conventional phenotype-based bioassays correlated with quantitative molecular endpoints derived from the toxicogenomics assay, suggesting that the selected protein biomarkers captured the main cellular effects that are associated with phenotypic adverse outcomes.

A thin carbon nanotube (CNT) and carbon black (CB) composite electroactive layer was cast-coated on a commercial forward osmosis (FO) membrane surface. The FO fouling rate reduction and fouling reversibility of several cathodic CNT membranes were evaluated under relatively severe fouling conditions using synthetic wastewater containing 107-109 P. fluorescens (PF) mL−1 as feed in zero-flushing and long-interval-flushing modes over 84 h. The mechanically pressed p(CNT + CB) had the best antifouling performance with ~40% fouling rate reduction and ~1–2 times fouling resistance recovery (FRR) as compared to the control. The p(CNT + CB) membrane was then selected to evaluate the cathodic membrane antifouling performance in a more realistic scenario using short-interval-flushing (2 min every 40 min) with either PF or actual wastewater (WW) as the FO feed solution. Experimental results suggest different primary fouling mechanisms for PF and WW due to differences in the feed solution matrix. Even so, the p(CNT + CB) cathode at 2 V reduced the initial immediate fouling flux loss by 63% for WW as well as the fouling rate by ~50% for both the PF and WW relative to the control. Application of an electric potential was necessary to achieve antifouling performance, which confirmed an electroactive fouling mitigation mechanism.

Controlled generation of reactive oxygen species (ROS) is essential in biological, chemical, and environmental fields, and piezoelectric catalysis is an emerging method to generate ROS, especially in sonodynamic therapy due to its high tissue penetrability, directed orientation, and ability to trigger in situ ROS generation. However, due to the low piezoelectric coefficient, and environmental safety and chemical stability concerns of current piezoelectric ROS catalysts, novel piezoelectric materials are urgently needed. Here, we demonstrate a method to induce polarization of inert poly(tetrafluoroethylene) (PTFE) particles ( ~ 1–5 μm) into piezoelectric electrets with a mild and convenient ultrasound process. Continued ultrasonic irradiation of the PTFE electrets generates ROS including hydroxyl radicals (•OH), superoxide (•O 2 − ) and singlet oxygen (1 O 2 ) at rates significantly faster than previously reported piezoelectric catalysts. In summary, ultrasonic activation of inert PTFE particles is a simple method to induce permanent PTFE polarization and to piezocatalytically generate aqueous ROS that is desirable in a wide-range of applications from environmental pollution control to biomedical therapy.

This study presents evidence of ultraviolet (UV) sensitive, ON center ganglion cells in the fish retina. We determined the spectral sensitivity of ON and OFF responses from the optic nerve mass potential in small (18.0 - 28.5 g) and large (59.5-835 g) rainbow trout, with special reference to UV sensitivity. Under a mid+long-wavelength adapting background, the ON response of small fish revealed the presence of a UV cone mechanism (lambda max 390 nm) which was absent in large specimens. Under similar background conditions, the OFF response of both small and large fish showed one sensitivity peak, dominated by inputs from an M-cone mechanism. An almost complete absence of the accessory corner cones from the retinal mosaic was correlated with the loss of UV sensitivity.