Chelation-directed interface engineering of in-place self-cleaning membranes.

Water-energy sustainability will depend upon the rapid development of advanced pressure-driven separation membranes. Although energy-efficient, water-treatment membranes are constrained by ubiquitous fouling, which may be alleviated by engineering self-cleaning membrane interfaces. In this study, a metal-polyphenol network was designed to direct the armorization of catalytic nanofilms (ca. 18 nm) on inert polymeric membranes. The chelation-directed mineralized coating exhibits high polarity, superhydrophilicity, and ultralow adhesion to crude oil, enabling cyclable crude oil-in-water emulsion separation. The in-place flux recovery rate exceeded 99.9%, alleviating the need for traditional ex situ cleaning. The chelation-directed nanoarmored membrane exhibited 48-fold and 6.8-fold figures of merit for in-place self-cleaning regeneration compared to the control membrane and simple hydraulic cleaning, respectively. Precursor interaction mechanisms were identified by density functional theory calculations. Chelation-directed armorization offers promise for sustainable applications in catalysis, biomedicine, environmental remediation, and beyond.

Facilely tuning the intrinsic catalytic sites of the spinel oxide for peroxymonosulfate activation: From fundamental investigation to pilot-scale demonstration.

Heterogeneous peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) have shown a great potential for pollutant degradation, but their feasibility for large-scale water treatment application has not been demonstrated. Herein, we develop a facile coprecipitation method for the scalable production (∼10 kg) of the Cu-Fe-Mn spinel oxide (CuFeMnO). Such a catalyst has rich oxygen vacancies and symmetry-breaking sites, which endorse it with a superior PMS-catalytic capacity. We find that the working reactive species and their contributions are highly dependent on the properties of target organic pollutants. For the organics with electron-donating group (e.g., -OH), high-valent metal species are mainly responsible for the pollutant degradation, whereas for the organics with electron-withdrawing group (e.g., -COOH and -NO2), hydroxyl radical (•OH) as the secondary oxidant also plays an important role. We demonstrate that the CuFeMnO-PMS system is able to achieve efficient and stable removal of the pollutants in the secondary effluent from a municipal wastewater plant at both bench and pilot scales. Moreover, we explore the application prospect of this PMS-based AOP process for large-scale wastewater treatment. This work describes an opportunity to scalably prepare robust spinel oxide catalysts for water purification and is beneficial to the practical applications of the heterogeneous PMS-AOPs.

Modulating Narrow Bandgap in a Diacetylene Functionalized Woven Covalent Organic Framework as a Visible Light Responsive Photocatalyst.

Woven covalent organic frameworks (COF) possess three dimensional frameworks with spatially isolated Cu(I) centers and have promising optoelectronic properties because of metal to ligand charge transfer (MLCT). However, despite their potential, woven COFs have not yet been investigated as photocatalysts. In this study, we developed a new woven COF, Cu-PhenBDA-COF, functionalized with diacetylene bonds. Cu-PhenBDA-COF was fully characterized, and the optoelectronic and photocatalytic properties were compared to previously reported Cu-COF-505. The diacetylene bonds of the linker positively impacted the optoelectronic properties of Cu-PhenBDA-COF and resulted in a narrower band gap and better charge separation efficiency. When the Cu(I) center was removed from both woven COFs, the absorption edge was blue shifted, resulting in a wider band gap, and there was a considerable decrease in the charge separation efficiency, underscoring the pivotal role of MLCT. This trend was reflected in the photocatalytic activity of the woven COFs toward the degradation of sulfamethoxazole in water, where the highest reaction rate constant (k app ) was recorded for the metallated diacetylene functionalized woven COF, Cu-PhenBDA-COF.

A Zwitterionic Hydrogel-Based Heterogeneous Fenton Catalyst for Water Treatment.

Persistent organic pollutants (POPs), including xenoestrogens and polyfluoroalkyl substances (PFAS), demand urgent global intervention. Fenton oxidation, catalyzed by iron ions, offers a cost-effective means to degrade POPs. However, numerous challenges like acid dependency, catalyst loss, and toxic waste generation hinder practical application. Efforts to create long-lasting heterogeneous Fenton catalysts, capable of simultaneously eliminating acid requirements, sustaining rapid kinetics, and retaining iron efficiently, have been unsuccessful. This study introduces an innovative heterogeneous zwitterionic hydrogel-based Fenton catalyst, surmounting these challenges in a cost-effective and scalable manner. The hydrogel, hosting individually complexed iron ions in a porous scaffold, exhibits substantial effective surface area and kinetics akin to homogeneous Fenton reactions. Complexed ions within the hydrogel can initiate Fenton degradation at neutral pH, eliminating acid additions. Simultaneously, the zwitterionic hydrogel scaffold, chosen for its resistance to Fenton oxidation, forms strong bonds with iron ions, enabling prolonged reuse. Diverging from existing designs, the catalyst proves compatible with UV-Fenton processes and achieves rapid self-regeneration during operation, offering a promising solution for the efficient and scalable degradation of POPs. The study underscores the efficacy of the approach by demonstrating the swift degradation of three significant contaminants-xenoestrogens, pesticides, and PFAS-across multiple cycles at trace concentrations.

Recent Advances of Bio-Based Hydrogel Derived Interfacial Evaporator for Sustainable Water and Collaborative Energy Storage Applications.

Solar interfacial evaporation strategy (SIES) has shown great potential to deal with water scarcity and energy crisis. Biobased hydrogel derived interfacial evaporator can realize efficient evaporation due to the unique structure- properties relationship. As such, increasing studies have focused on water treatment or even potential accompanying advanced energy storage applications with respect of efficiency and mechanism of bio-based hydrogel derived interfacial evaporation from microscale to molecular scale. In this review, the interrelationship between efficient interfacial evaporator and bio-based hydrogel is first presented. Then, special attention is paid on the inherent molecular characteristics of the biopolymer related to the up-to-date studies of promising biopolymers derived interfacial evaporator with the objective to showcase the unique superiority of biopolymer. In addition, the applications of the bio-based hydrogels are highlighted concerning the aspects including water desalination, water decontamination atmospheric water harvesting, energy storage and conversion. Finally, the challenges and future perspectives are given to unveil the bottleneck of the biobased hydrogel derived SIES in sustainable water and other energy storage applications.

High-Performance Multifunctional Carbon Fibrous Sponges Derived from Pitch.

3D carbon-based porous sponges are recognized for significant potential in oil absorption and electromagnetic interference (EMI). However, their widespread application is hindered by a common compromise between high performance and affordability of mass production. Herein, a novel approach is introduced that involves laser-assisted micro-zone heating melt-blown spinning (LMHMS) to address this challenge by creating pitch-based submicron carbon fibers (PSCFs) sponge with 3D interconnected structures. These structures bestow the resulting sponge exceptional characteristics including low density (≈20 mg cm-3), high porosity (≈99%), remarkable compressibility (80% maximum strain), and superior conductivity (≈628 S m-1). The resultant PSCF sponges realize an oil/organic solvent sorption capacity over 56 g/g and possess remarkable regenerated ability. In addition to their effectiveness in cleaning up oil/organic solvent spills, they also demonstrated strong electromagnetic shielding capabilities, with a total shielding effectiveness (SE) exceeding 60 dB across the X-band GHz range. In virtue of extreme lightweight of ≈20 mg cm-3, the specific SE of the PSCF sponge reaches as high as ≈1466 dB cm3 g-1, surpassing the performance of numerous carbon-based porous structures. Thus, the unique blend of properties renders these sponges promising for transforming strategies in addressing oil/organic solvent contaminations and providing effective protection against EMI.

Recyclable Biomimetic Sunflower Pollen-based Photocatalyst for Enhanced Degradation of Pharmaceuticals.

Recent trends in addressing the impending water crisis focus on the development of innovative water treatment methods. This work utilizes pollen as a core template to synthesize highly efficient onion-like photocatalysts for pollutant mineralization. The study showcases a novel electrochemical synthesis method that maintains the structural integrity of pollen, resulting in increased surface area and enhanced photocatalytic activity. After 90-min of visible light irradiation, over 99% mineralization is achieved. These hybrid photocatalysts demonstrate exceptional stability and efficacy in degrading pollutants. The used photocatalysts can be recycled into biopellets with an ash content of less than 7% (weight), moisture content of less than 8% (weight), and a calorific value of ≈22.1 ± 0.3 MJ kg-1. Additionally, the resulting ashes serve as effective peroxymonosulphate activators for pollutant mineralization. This process offers sustainable waste management while minimizing waste production, providing a practical solution for water purification. The efficacy of this approach in pollutant removal is underscored by mineralization rates exceeding 99%.

Asymmetrically Coordinated Mn-S1N3 Configuration Induces Localized Electric Field-Driven Peroxymonosulfate Activation for Remarkably Efficient Generation of 1O2.

Singlet oxygen (1O2) species generated in peroxymonosulfate (PMS)-based advanced oxidation processes offer opportunities to overcome the low efficiency and secondary pollution limitations of existing AOPs, but efficient production of 1O2 via tuning the coordination environment of metal active sites remains challenging due to insufficient understanding of their catalytic mechanisms. Herein, an asymmetrical configuration characterized by a manganese single atom coordinated is established with one S atom and three N atoms (denoted as Mn-S1N3), which offer a strong local electric field to promote the cleavage of O─H and S─O bonds, serving as the crucial driver of its high 1O2 production. Strikingly, an enhanced the local electric field caused by the dynamic inter-transformation of the Mn coordination structure (Mn-S1N3 ↔ Mn-N3) can further downshift the 1O2 production energy barrier. Mn-S1N3 demonstrates 100% selective product 1O2 by activation of PMS at unprecedented utilization efficiency, and efficiently oxidize electron-rich pollutants. This work provides an atomic-level understanding of the catalytic selectivity and is expected to guide the design of smart 1O2-AOPs catalysts for more selective and efficient decontamination applications.

Pd Clusters Loaded with Multivalent Cu Foam for Superior Electrochemical Nitrate Reduction and Selective N≡N Bond Formation.

The electrochemical denitrification of nitrate (NO3 -) in actual wastewater to nitrogen (N2) is an effective approach to reversing the current imbalance of the nitrogen cycle and the eutrophication of water. However, electrostatic repulsion between NO3 - and the cathode results in the low efficiency of NO3 - reduction reaction (NO3RR). Here, density functional theory (DFT) calculations are used as a theoretical guide to design a Pd cluster-loaded multivalent Cu foam (Pd/Cu2O-CF) electrocatalyst, which achieves a splendid 97.8% NO3 - removal rate, 97.9% N2 selectivity, 695.5 mg N g-1 Pd h-1 reduction efficiency, and 60.0% Faradaic efficiency at -1.3 V versus SCE. The projected density of states (pDOS) indicates that NO3 - and Pd/Cu2O-CF are bonded via strong complexation between the O 2p (in NO3 -) and Cu 3d (in Cu2O) with the input of voltage, which reduces the electrostatic repulsion and enhances the enrichment of NO3 - on the cathode. In-situ characterizations demonstrate that Pd[H] can reduce Cu2O to Cu, and subsequently Cu reduces NO3 - to nitrite (NO2 -) accompanied by in situ reconfiguration of multivalent Cu foam. NO2 - is then transferred to the surface of Pd clusters by the cascade catalysis and accelerates the breaking of N─O bonds to form Pd─N, and eventually achieves the N≡N bond formation.

Constructing Nano-Heterostructure with Dual-Site to Boost H2O2 Activation and Regulate the Transformation of Free Radicals.

A major issue with Fenton-like reaction is the excessive consumption of H2O2 caused by the sluggish regeneration rate of low-valent metal, and how to improve the activation efficiency of H2O2 has become a key in current research. Herein, a nano-heterostructure catalyst (1.0-MnCu/C) based on nano-interface engineering is constructed by supporting Cu and MnO on carbon skeleton, and its kinetic rate for the degradation of tetracycline hydrochloride is 0.0436 min-1, which is 2.9 times higher than that of Cu/C system (0.0151 min-1). The enhancement of removal rate results from the introduced Mn species can aggregate and transfer electrons to Cu sites through the electron bridge Mn-N/O-Cu, thus preventing Cu2+ from oxidizing H2O2 to form O2 •-, and facilitating the reduction of Cu2+ and generating more reactive oxygen species (1O2 and ·OH) with stronger oxidation ability, resulting in H2O2 utilization efficiency is 1.9 times as much as that of Cu/C. Additionally, the good and stable practical application capacity in different bodies demonstrates that it has great potential for practical environmental remediation.

Biodegradation of the cyanobacterial toxin anatoxin-a by a Bacillus subtilis strain isolated from a eutrophic lake in Saudi Arabia.

Anatoxin-a (ATX-a) is a neurotoxin produced by some species of cyanobacteria. Due to its water solubility and stability in natural water, it could pose health risks to human, animals, and plants. Conventional water treatment techniques are not only insufficient for the removal of ATX-a, but they also result in cell lysis and toxin release. The elimination of this toxin through biodegradation may be a promising strategy. This study examines for the first time the biodegradation of ATX-a to a non-toxic metabolite (Epoxy-ATX-a) by a strain of Bacillus that has a history of dealing with toxic cyanobacteria in a eutrophic lake. The Bacillus strain AMRI-03 thrived without lag phase in a lake water containing ATX-a. The strain displayed fast degradation of ATX-a, depending on initial toxin concentration. At the highest initial concentrations (50 & 100 µg L- 1), total ATX-a degradation took place in 4 days, but it took 6 & 7 days at lower concentrations (20, 10, and 1 µg L- 1, respectively). The ATX-a biodegradation rate was also influenced by the initial toxin concentration, reaching its maximum value (12.5 µg L- 1 day- 1) at the highest initial toxin concentrations (50 & 100 µg L- 1). Temperature and pH also had an impact on the rate of ATX-a biodegradation, with the highest rates occurring at 25 and 30 ºC and pH 7 and 8. This nontoxic bacterial strain could be immobilized within a biofilm on sand filters and/or sludge for the degradation and removal of ATX-a and other cyanotoxins during water treatment processes, following the establishment of mesocosm experiments to assess the potential effects of this bacterium on water quality.

Antimicrobial activity and nanoremediation of heavy metals using biosynthesized CS/GO/ZnO nanocomposite by Bacillus subtilis ATCC 6633 alone or immobilized in a macroporous cryogel.

BACKGROUND: The world society is still suffering greatly from waterborne infections, with developing countries bearing most of the morbidity and death burden, especially concerning young children. Moreover, microbial resistance is one of the most prevalent global problems that extends the need for self-medication and the healing period, or it may be linked to treatment failure that results in further hospitalization, higher healthcare expenses, and higher mortality rates. Thus, innovative synthesis of new antimicrobial materials is required to preserve the environment and enhance human health. RESULTS: The present study highlighted a simple and cost-effective approach to biosynthesize a chitosan/graphene oxide/zinc oxide nanocomposite (CS/GO/ZnO) alone and immobilized in a macroporous cryogel as a new antimicrobial agent. Bacillus subtilis ATCC 6633 was used as a safe and efficient bio-nano-factory during biosynthesis. The formation of CS/GO/ZnO was confirmed and characterized using different analyses including ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), selective area diffraction pattern (SADP), Zeta analyses, scanning electron microscope (SEM) and transmission electron microscopy (TEM). GO combined with ZnO NPs successfully and displayed an adsorption peak at 358 nm. The XRD results showed the crystalline composition of the loaded ZnO NPs on GO sheets. FTIR spectrum confirmed the presence of proteins during the synthesis which act as stabilizing and capping agents. The nanocomposite has a high negative surface charge (-32.8 ± 5.7 mV) which increases its stability. SEM and TEM showing the size of biosynthesized ZnO-NPs was in the range of 40-50 nm. The CS/GO/ZnO alone or immobilized in cryogel revealed good antimicrobial activities against B. cereus ATCC 14,579, Escherichia coli ATCC 25,922, and Candida albicans ATCC 10,231 in a dose-dependent manner. The CS/GO/ZnO cryogel revealed higher antimicrobial activity than GO/ZnO nanocomposite and standard antibiotics (amoxicillin and miconazole) with inhibition zones averages of 24.33 ± 0.12, 15.67 ± 0.03, and 17.5 ± 0.49 mm, respectively. The MIC values of the prepared nanocomposite against B. cereus, E. coli, and C. albicans were 80, 80, and 90 µg/ml compared to standard drugs (90, 120 and 150 µg/ml, respectively). According to the TEM ultrastructure studies of nanocomposite-treated microbes, treated cells had severe deformities and morphological alterations compared to the untreated cells including cell wall distortion, the separation between the cell wall and plasma membrane, vacuoles formation moreover complete cell lyses were also noted. In the cytotoxicity test of CS/GO/ZnO alone and its cryogel, there was a significant reduction (p˂0.05) in cell viability of WI-38 normal lung cell line after the concentration of 209 and 164 µg/ml, respectively. It showed the low toxic effect of the nanocomposite and its cryogel on the WI-38 line which implies its safety. In addition, water treatment with the CS/GO/ZnO cryogel decreased turbidity (0.58 NTU), total coliform (2 CFU/100 ml), fecal coliform (1 CFU/100 ml), fecal Streptococcus (2 CFU/100 ml), and heterotrophic plate counts (53 CFU/1 ml) not only in comparison with the chlorine-treated samples (1.69 NTU, 4 CFU/100 ml, 6 CFU/100 ml, 57 CFU/100 ml, and 140 CFU/1 ml, respectively) but also with the raw water samples (6.9 NTU, 10800 CFU/100 ml, 660 CFU/100 ml, 800 CFU/100 ml, and 4400 CFU/1 ml, respectively). Moreover, cryogel significantly decreased the concentration of different heavy metals, especially cobalt compared to chlorine (0.004 ppm, 0.002 ppm, and 0.001 ppm for raw water, chlorine-treated, and cryogel-treated groups, respectively) which helped in the reduction of their toxic effects. CONCLUSION: This study provides an effective, promising, safe, and alternative nanocomposite to treat different human and animal pathogenic microbes that might be used in different environmental, industrial, and medical applications.

One story as part of the Global Conversation on Sustainability: dye adsorption studies using a novel bio-derived calcite material.

Many of the United Nations' Sustainable Development Goals (SDGs) can be addressed through chemistry. Researchers at Memorial University of Newfoundland, Canada, have been sharing their stories on September 25 for the past two years through the Global Conversation on Sustainability. This article describes the details of one of these stories. As the global population increases, food production including aquaculture is increasing to provide for this. At the same time, this means more waste is produced. Waste from aquaculture is often overlooked as a source of valuable chemicals. By-products from farming blue mussels (Mytilus edulis) is dominated by shells rich in calcite. A 'soft' calcite material prepared from waste mussels, via a combination of heat and acetic acid treatment, was investigated for its adsorptive properties and its possible use in wastewater remediation. The adsorption of two cationic dyes, methylene blue and safranin-O, on this material were evaluated through isothermal and kinetic modelling. The adsorption systems for both methylene blue and safranin-O can best be described using Langmuir isotherms and the respective adsorption capacities were 1.81 and 1.51 mg/g. The adsorption process was dominated by pseudo-second order rate kinetics. Comparisons are made with other mollusc-derived materials reported to date.

Effect of sandblasting and acid surface pretreatment on the specific capacitance of CuO nanostructures grown by hot water treatment for supercapacitor electrode applications.

Crystalline copper oxide (CuO) nanostructures with micro, nano, and micro-nano surface roughness were grown on Cu sheet substrates by a facile, scalable, low-cost, and low-temperature hot water treatment (HWT) method that simply involved immersing Cu sheet in DI water at 75 °C for 24 h without any chemical additives. Various morphological features and sizes of CuO nanostructures were tuned by using different surface pretreatment techniques including acid treatment, sandblasting, or a combination of those two. The surface morphology of the prepared samples was analyzed by scanning electron microscopy. The crystal structure of the CuO nanostructures was investigated by x-ray diffraction XRD and Raman spectroscopy. To study the pseudocapacitive behavior, their potential supercapacitor performance, and equivalent series resistance, electrochemical analysis was done by cyclic voltammetry and electrochemical impedance spectroscopy for all the CuO/Cu samples in 1 M of Na2SO4electrolyte. Among all, the best supercapacitive performance was achieved for CuO/Cu samples pretreated with Sandblasting followed by Acid treatment resulting in a specific capacitance of about 104 F g-1. The electrode with the sandblasted + acid pretreated sample showed a maximum of ∼69% capacitive retention after 2000 consecutive cycles. Our results indicate that CuO nanostructures on Cu substrates prepared with different surface pretreatment conditions and grown by HWT can be promising electrodes for supercapacitor device applications.

Discerning the Relevance of Singlet Oxygen in Pollutant Degradation in Peroxymonosulfate Activation Processes.

Significant efforts have recently been exerted toward construction of singlet oxygen (1O2)-dominated catalytic oxidation systems for selective removal of organic contaminants from wastewater, with peroxides serving as the chemical source. However, the relevance of 1O2 in the removal of pollutants remains ambiguous and requires elucidation. In this study, we scrupulously exclude the significant role of 1O2 in contaminant degradation in various peroxymonosulfate (PMS) activation systems. Multiple experimental results indicate that the activation of PMS catalyzed by CuO, MnO2, Fe-doped g-C3N4 (Fe-CN), or N-doped graphite does not predominantly follow the 1O2 pathway. More importantly, the reactivity of 1O2 is remarkably overestimated in the literature, given its inferior capacity in degradation of a range of heterocyclic contaminants and aromatic compounds possessing electron-withdrawing groups. In addition, the strong physical quenching effect of water, coupled with the low oxidizing ability of 1O2, would notably reduce the utilization efficiency of peroxide, which is particularly apparent in the degradation of micropollutants. We reckon that this study is expected to end the long-running dispute associated with the relevance of 1O2 in pollutant removal.

Understanding Variations in Ferrate Detection through the ABTS Method in the Presence of Electron-Rich Organic Compounds.

The chromogenic reaction between 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) and ferrate [Fe(VI)] has long been utilized for Fe(VI) content measurement. However, the presence of electron-rich organic compounds has been found to significantly impact Fe(VI) detection using the ABTS method, leading to relative errors ranging from ∼88 to 100%. Reducing substances consumed ABTS•+ and resulted in underestimated Fe(VI) levels. Moreover, the oxidation of electron-rich organics containing hydroxyl groups by Fe(VI) could generate a phenoxyl radical (Ph•), promoting the transformation of Fe(VI) → Fe(V) → Fe(IV). The in situ formation of Fe(IV) can then contribute to ABTS oxidation, altering the ABTS•+:Fe(VI) stoichiometry from 1:1 to 2:1. To overcome these challenges, we introduced Mn(II) as an activator and 3,3',5,5'-tetramethylbenzidine (TMB) as a chromogenic agent for Fe(VI) detection. This Mn(II)/TMB method enables rapid completion of the chromogenic reaction within 2 s, with a low detection limit of approximately 4 nM and a wide detection range (0.01-10 µM). Importantly, the Mn(II)/TMB method exhibits superior resistance to reductive interference and effectively eliminates the impact of phenoxyl-radical-mediated intermediate valence iron transfer processes associated with electron-rich organic compounds. Furthermore, this method is resilient to particle interference and demonstrates practical applicability in authentic waters.

Aerobic Denitrification Promoting by Actinomycetes Coculture: Investigating Performance, Carbon Source Metabolic Characteristic, and Raw Water Restoration.

The coculture theory that promotes denitrification relies on effectively utilizing the resources of low-efficiency denitrification microbes. Here, the strains Streptomyces sp. PYX97 and Streptomyces sp. TSJ96 were isolated and showed lower denitrification capacity when cultured individually. However, the coculture of strains PYX97 and TSJ96 enhanced nitrogen removal (removed 96.40% of total nitrogen) and organic carbon reduction (removed 92.13% of dissolved organic carbon) under aerobic conditions. Nitrogen balance analysis indicated that coculturing enhanced the efficiency of nitrate converted into gaseous nitrogen reaching 70.42%. Meanwhile, the coculturing promoted the cell metabolism capacity and carbon source metabolic activity. The coculture strains PYX97 and TSJ96 thrived in conditions of C/N = 10, alkalescence, and 150 rpm shaking speed. The coculturing reduced total nitrogen and CODMn in the raw water treatment by 83.32 and 84.21%, respectively. During this treatment, the cell metabolic activity and cell density increased in the coculture strains PYX97 and TSJ96 reactor. Moreover, the coculture strains could utilize aromatic protein and soluble microbial products during aerobic denitrification processes in raw water treatment. This study suggests that coculturing inefficient actinomycete strains could be a promising approach for treating polluted water bodies.

Influence of Amino Acid Substitutions in Capsid Proteins of Coxsackievirus B5 on Free Chlorine and Thermal Inactivation.

The sensitivity of enteroviruses to disinfectants varies among genetically similar variants and coincides with amino acid changes in capsid proteins, although the effect of individual substitutions remains unknown. Here, we employed reverse genetics to investigate how amino acid substitutions in coxsackievirus B5 (CVB5) capsid proteins affect the virus' sensitivity to free chlorine and heat treatment. Of ten amino acid changes observed in CVB5 variants with free chlorine resistance, none significantly reduced the chlorine sensitivity, indicating a minor role of the capsid composition in chlorine sensitivity of CVB5. Conversely, a subset of these amino acid changes located at the C-terminal region of viral protein 1 led to reduced heat sensitivity. Cryo-electron microscopy revealed that these changes affect the assembly of intermediate viral states (altered and empty particles), suggesting that the mechanism for reduced heat sensitivity could be related to improved molecular packing of CVB5, resulting in greater stability or altered dynamics of virus uncoating during infection.

Excessive Ozonation Stress Triggers Severe Membrane Biofilm Accumulation and Fouling.

The established benefits of ozone on microbial pathogen inactivation, natural organic matter degradation, and inorganic/organic contaminant oxidation have favored its application in drinking water treatment. However, viable bacteria are still present after the ozonation of raw water, bringing a potential risk to membrane filtration systems in terms of biofilm accumulation and fouling. In this study, we shed light on the role of the specific ozone dose (0.5 mg-O3/mg-C) in biofilm accumulation during long-term membrane ultrafiltration. Results demonstrated that ozonation transformed the molecular structure of influent dissolved organic matter (DOM), producing fractions that were highly bioavailable at a specific ozone dose of 0.5, which was inferred to be a turning point. With the increase of the specific ozone dose, the biofilm microbial consortium was substantially shifted, demonstrating a decrease in richness and diversity. Unexpectedly, the opportunistic pathogen Legionella was stimulated and occurred in approximately 40% relative abundance at the higher specific ozone dose of 1. Accordingly, the membrane filtration system with a specific ozone dose of 0.5 presented a lower biofilm thickness, a weaker fluorescence intensity, smaller concentrations of polysaccharides and proteins, and a lower Raman activity, leading to a lower hydraulic resistance, compared to that with a specific ozone dose of 1. Our findings highlight the interaction mechanism between molecular-level DOM composition, biofilm microbial consortium, and membrane filtration performance, which provides an in-depth understanding of the impact of ozonation on biofilm accumulation.

Compaction of Pressure-Driven Water Treatment Membranes: Real-Time Quantification and Analysis.

Water treatment membranes play crucial roles in applications such as desalination, wastewater treatment, and potable water reuse. In a prior study, we introduced a novel method, combining electrical impedance spectroscopy with dynamic mechanical analysis, to quantify single-layer homogeneous membrane compaction up to 12.5 psi. Now we extend the method's capabilities to quantify real-time compaction of multilayer heterogeneous nanofiltration and reverse osmosis (RO) membranes up to 330 psi. Our findings demonstrate that membrane compaction does not solely occur in the support/backing layer. The air pockets between the polysulfone support and the polyester backing layers, which were not discussed previously, account for up to 18% and 14% of total membrane compaction for the nanofiltration and RO membranes. For the nanofiltration membrane, the majority of compaction (up to 45%) occurs in the void spaces of the backing layer, while for the RO membrane, the majority of compaction (up to 40%) occurs in the solid material of the backing layer. We also confirm, with experimental results, the importance of using compressive testing instead of tensile testing to accurately characterize compaction. Membrane fatigue is characterized by experimental trends including: increasing irrevocable compaction, increasing creep/instantaneous compaction ratios, and increasing strains in hysteresis experiments.