New method for measuring the pore sizes and pore size distributions of filter membranes-the fluorescence probe method.

A novel, simple, and rapid method is demonstrated for measuring the pore size and pore size distribution of filtration membranes (FMs) used in aqueous applications with fluorescence probes. Because the selected fluorescent probes are mixable and have strong signals, combined with the operation of dead-end filtration, this method only requires small amounts of reagents; additionally, it is time-efficient by avoiding multiple rounds of filtration. This method detects the size of a FM pore throat (i.e., the narrowest position of a pore tunnel), which is more consistent with the actual filtration situation. The conditions, such as probe concentration, temperature, transmembrane pressure difference, and types of surfactants, have been optimized. The experimental results show that the fluorescence probe method has good accuracy and reproducibility for measuring the pore size and pore size distribution of both organic and inorganic FMs. The method is particularly suitable for rapid testing of the filtration performance (nominal pore size≥0.02 µm) of purchased or synthetic membranes in the laboratory.

A High-Performance Alginate Hydrogel Binder for Aqueous Zn-Ion Batteries.

The binder is an indispensable battery component that maintains the integrity of the electrode. Polyvinylidene fluoride (PVDF) is most commonly used as a binder in rechargeable batteries; however, it is associated with the toxic and expensive N-methyl-2-pyrrolidone organic solvent. Here, through the cross-linking of sodium alginate (SA) with metal cations, a high-performance hydrogel binder is developed that maintains the stability of MnO2 cathodes in an aqueous electrolyte. Owing to the strong adhesion, high hydrophilicity, and good mechanical stability resulting from the strong bonding of Ca2+ with SA, a commercial microsized MnO2 cathode with a Ca-SA binder delivered a capacity above 300 mAh/g at 1 C, which was larger than those of Mn-SA and Zn-SA (∼200 mAh/g) and PVDF (∼150 mAh/g) binders, and a capacity of 250 mAh/g at 3 C for over 200 cycles. These encouraging results could unlock the enormous potential of aqueous binders for practical applications in aqueous batteries.

Development of pattern recognition based on nanosheet-DNA probes and an extendable DNA library.

Pattern recognition, also called "array sensing," is a recognition strategy with a wide and expandable analysis range, based on high-throughput analysis data. In this work, we constructed a sensor array for the identification of targets including bacterial pathogens and proteins by using FAM-labeled DNA probes and 2D nanosheet materials. We designed an ordered and extendible DNA library for the collection of recognition probes. Unlike traditional DNA probes with random and massive sequences, our DNA library was constructed following a 5-digit binary number (00000-11111, 0 = CCC, and 1 = TTT), and especially, 8 special symmetry sequences were chosen from the library. Two different nanosheet materials were used as the quencher. When targets were added, the interaction between DNA and the nanosheets was competitively affected, and as a result, the fluorescence signal changed accordingly. Finally, by using our fluorescent sensor array, 17 bacteria and 8 proteins were precisely recognized. We believe that our work has provided a simple and valuable strategy for the improvement of the recognition range and discrimination precision for the development of pattern recognition.

A polyA DNA probe-based ultra-sensitive and structure-distinguishable electrochemical biosensor for the analysis of RNAi transgenic maize.

Since the application of RNA interference (RNAi) is rapidly developing in GMO technology, accurate and sensitive detection of functional RNA molecules was urgently needed, for the safety and functional assessment of RNAi crops. In this work, we developed an electrochemical biosensor for transgene-derived long RNA based on a poly-adenine (polyA) DNA capture probe. The polyA self-assembling monolayer (SAM) provided enhanced interface stability and optimized surface density for the subsequent hybridization of the long RNA molecule. A multiple reporter probe system (MRP) containing 12 reporter probes (RPs) and 2 spacers was applied to open the complex molecular secondary structure and hybridize with the long RNA, with the critical assistance of dimethyl sulfoxide (DMSO). By using 3 addressable RPs, structural recognition was performed among long stem-loop RNA, long dsRNA (no loop), and siRNA. Excellent selectivity was achieved when the extracted total RNA samples were directly analyzed. When reverse transcription recombinase polymerase amplification (RT-RPA) technology was combined, the sensitivity was improved to 10 aM. To the best of our knowledge, this is the first electrochemical biosensor with the excellent capability of quantification and structural analysis of the long RNA of the RNAi GMO. Our work shows great potential in a wide range of RNAi GMO samples.

Degradation of imidacloprid by UV-activated persulfate and peroxymonosulfate processes: Kinetics, impact of key factors and degradation pathway.

UV-activated persulfate (UV/PS) and peroxymonosulfate (UV/PMS) processes as alternative methods for removal of imidacloprid (IMP) were conducted for the first time. The reaction rate constants between IMP and the sulfate or hydroxyl radical were calculated as 2.33×109  or 2.42×1010 M-1 s-1, respectively. The degradation of IMP was greatly improved by UV/PS and UV/PMS compared with only UV or oxidant. At any given dosage, UV/PS achieved higher IMP removal rate than UV/PMS. The pH range affecting the degradation in the UV/PS and UV/PMS systems were different in the ranges of 6-8 and 9 to 10. SO42-, F- and NO3- had no obvious effect on the degradation in the UV/PS and UV/PMS systems. CO32- and PO43- inhibited the degradation of IMP in the UV/PS system, while they enhanced the degradation in the UV/PMS system. Algae organic matters (AOM) were used to consider the impact of the degradation of IMP for the first time. The removal of IMP were restrained by both AOM and natural organic matters. The higher removal rate of IMP demonstrated that both UV/PS and UV/PMS were suitable for treating the water containing IMP, while UV/PS was cost-effective than UV/PMS based on the total cost calculation. Finally, the degradation pathways of IMP were proposed.

Response Surface Optimization of an Extraction Method for the Simultaneous Detection of Sulfamethoxazole and 17ß-Estradiol in Soil.

Antibiotics and hormones widely exist in fertilizers and manures, which are excessively used in agriculture and animal husbandry. Considering their potential harm to the environment and human health, the detection of antibiotics and hormones has become a necessity. However, current methods find it difficult to simultaneously extract and detect antibiotics and hormones in soil and to maintain a high level of accuracy and a low cost. In this study, a straightforward, convenient, and simultaneous extraction and detection method of a representative antibiotic (sulfamethoxazole, SMZ) and hormone (17ß-Estradiol, E2) in soil has been established. Ultrasound-assisted extraction (UAE) was used in the pretreatment process and high-performance liquid chromatography with the ultraviolet detector (HPLC-UV) method was then chosen in the detection process. By means of single factors and response surface experiments, optimal extraction conditions were a 41-mL buffer solution (pH 4.27) mixed with 1 g of soil sample, an ultrasonication time of 36 min, an ultrasonication temperature of 25 °C, and two extraction cycles. The detection limits of 0.3-10 µg/kg and quantification limits of 1-30 µg/kg have been obtained. Finally, the optimized simultaneous extraction and detection method was validated by three different real soil samples with recoveries ranging from 79.49% to 86.47%.

Performance of diatomite/iron oxide modified nonwoven membrane used in membrane bioreactor process for wastewater reclamation.

This study describes an approach for surface modification of a nonwoven membrane by diatomite/iron oxide to examine its filterability. Analysis results showed that nonwoven hydrophilicity is enhanced. Static contact angle decreases dramatically from 122.66° to 39.33°. Scanning electron micrograph images show that diatomite/iron oxide is attached on nonwoven fiber. X-ray diffraction analysis further proves that the compound is mostly magnetite. Fourier transformed infrared spectra results reveal that two new absorption peaks might be attributed to Si-O and Fe-O, respectively. Modified and original membranes were used in double nonwoven membrane bioreactors (MBRs) for synthetic wastewater treatment. High critical flux, long filtration time, slow trans-membrane pressure rise and stable sludge volume index confirmed the advantages of modified nonwoven. Comparing with original nonwoven, similar effluent qualities are achieved, meeting the requirements for wastewater reclamation.

Toxicological responses of the earthworm Eisenia fetida to 18-crown-6 under laboratory conditions.

The earthworm Eisenia fetida was exposed to artificial soil supplemented with 18-crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane) to investigate its effects on earthworm mortality, growth, avoidance, burrowing behavior and respiration. The results revealed that 18-crown-6 had the potential to negatively affect the behavior of earthworms. The 7-d LC50 was 585 mg kg(-1) soil. Avoidance behavior was the most sensitive endpoint, with a 48-h EC50 of 120 mg kg(-1) soil. Growth, burrow length and respiration showed general decreases with increasing 18-crown-6 concentrations. Behavioral endpoints and respiration may be regarded as sensitive parameters in evaluating the toxicity of this chemical to earthworms.

Preparation of cross-linked magnetic chitosan with quaternary ammonium and its application for Cr(VI) and P(V) removal.

Pollutants that exist in anionic species are issues of concern in water treatment. Compared to cationic pollutants, the removal of anionic pollutants by adsorption is more difficult because most adsorbents carry predominantly negative charges in neutral and alkaline environments. In this study, a cross-linked chitosan derivative with quaternary ammonium and magnetic properties (QM-chitosan) was prepared and employed to remove chromium (VI) and phosphorus (V) (Cr(VI) and P(V)) from aqueous environments. The QM-chitosan was characterized by Fourier transform infrared spectrometry (FT-IR), thermogravimetric analysis (TGA), energy dispersive X-ray (SEM-EDX) and zeta potential. Batch experiments show that QM-chitosan can effectively remove Cr(VI) and P(V), and the main mechanism was believed to be electrostatic interaction. A pseudo second-order model was fitted to describe the kinetic processes of Cr(VI) and P(V) removal. The adsorption isotherms of both Cr(VI) and P(V) on the QM-chitosan were well fitted by the Langmuir isotherm equation. The saturated adsorption capacity of P(V) (2.783 mmol/g) was found to be higher than that of Cr(VI) (2.323 mmol/g), resulting from the size of the H(2)PO(4)(-) ions being smaller than that of the HCrO(4)(-) ions. However, the theoretical calculation and experimental results showed that QM-chitosan had a stronger affinity for Cr(VI) than P(V). The adsorption-desorption of the QM-chitosan was evaluated, and high regeneration rates were demonstrated.

SiO2 Modification of Silicon Carbide Membrane via an Interfacial In Situ Sol-Gel Process for Improved Filtration Performance.

Silicon carbide (SiC) membrane has emerged as a promising class of inorganic ceramic membranes with many advantageous attributes and has been used for a variety of industrial microfiltration (MF) processes. The state-of-the-art industrial manufacturing of SiC membranes based on the particle sintering method can only achieve an average pore size that ranges from 40 nm to a few micrometers, which is still unsatisfactory for ultrafiltration (UF) applications. Thus, the pore size control of SiC membranes remains a focus of continuing study. Herein, we provide an in situ sol-gel modification strategy to tailor the pore size of SiC membranes by a superficial deposition of SiO2 onto the membrane surface and membrane pore channels. Our in situ sol-gel modification method is simple and effective. Furthermore, the physical characteristics and the filtration performance of the membrane can easily be controlled by the in situ reaction time. With an optimal in situ reaction time of 30 min, the average pore size of the membrane can be reduced from macropores (400 nm) to mesopores (below 20 nm), and the retention ability for 20 nm fluorescent PS microspheres can be improved from 5% to 93%; the resultant SiC/SiO2 composite membranes are imparted with water permeance of 77 L·m-2·h-1·bar-1, improved anti-protein-fouling properties, excellent performance, and anti-acid stabilities. Therefore, modified SiC/SiO2 membranes based on the in situ sol-gel process have great potential as UF membranes for a variety of industrial processes.

Spatiotemporal analysis of the future carbon footprint of solar electricity in the United States by a dynamic life cycle assessment.

Solar photovoltaics (PVs) installation would increase 20-fold by 2050; however, considerable greenhouse gas (GHG) emissions are generated during the cradle-to-gate production, with spatiotemporal variances depending on the grid emission. Thus, a dynamic life cycle assessment (LCA) model was developed to assess the accumulated PV panels with a heterogeneous carbon footprint if manufactured and installed in the United States. The state-level carbon footprint of solar electricity (CFE PV-avg) from 2022 to 2050 was estimated using several cradle-to-gate production scenarios to account for emissions stemming from electricity generated from solar PVs. The CFE PV-avg (min 0.032, max 0.051, weighted avg. 0.040 kg CO2-eq/kWh) in 2050 will be significantly lower than that of the comparison benchmark (min 0.047, max 0.068, weighted avg. 0.056 kg CO2-eq/kWh). The proposed dynamic LCA framework is promising for planning solar PV supply chains and, ultimately, the supply chain of an entire carbon-neutral energy system to maximize the environmental benefits.

Ball-milled sulfide iron-copper bimetals based composite permeable materials for Cr (VI) removal: Effects of preparation parameters and kinetics study.

Zero-valent iron (ZVI) and modified ZVI have been investigated extensively for groundwater remediation. However, ZVI based powder was difficult to be applied directly as permeable reactive barrier (PRB) materials due to their low water permeability and usage rate. In this study, sulfide iron-copper bimetal was prepared by ball milling, which is environment-friendly without second contamination. The optimal preparation parameters of sulfide iron-copper bimetal for Cr(VI) removal were determined (Cu/Fe ratio (w/w), 0.018; FeS/Fe ratio (w/w), 0.1213; ball milling speed, 450 rpm; ball milling time, 5 h). A composite permeable material was prepared by sintering a mixture of sulfide iron-copper bimetal, sludge, and kaolin. The parameters for composite permeable material preparation including sludge content and particle size, and sintering time were optimized, which were 60%, 60-75 mesh, and 4 h, respectively. The optimal composite permeable material was characterized by SEM-EDS, XRD, and FTIR. The results demonstrated preparation parameters can affect the hydraulic conductivity and hardness of composite permeable material. High sludge content, small particles size, and moderate sintering time resulted in high permeability of composite permeable material and were beneficial for Cr(VI) removal. The dominant Cr(VI) removal mechanism was reduction, and the reaction followed pseudo-first order kinetics. Conversely, low sludge content and large particle size, and long sintering time lead to low permeability of composite permeable material. Chromate removal was mainly by chemisorption following pseudo-second order kinetics. The hydraulic conductivity and hardness of the optimal composite permeable material achieved 1.732 cm/s and 50, respectively. The results of column experiments indicated that its Cr(VI) removal capacity was 0.54 mg/g, 0.39 mg/g and 0.29 mg/g at pH 5, 7 and 9, respectively. The ratio of Cr(VI) to Cr(III) on composite permeable material surface was similar under acidic and alkaline conditions. This study will provide an effective reactive material of PRB for field application.

COVID-19 pandemic: impacts on air quality and economy before, during and after lockdown in China in 2020.

This paper comprehensively evaluates the dynamic effects on China's environment and economy during the COVID-19 pandemic. Results show that the COVID-19 lockdown resulted in a temporary improvement in air quality. Furthermore, nitrogen dioxide (NO2) levels in the atmosphere in China were 36% lower than in the week after last year's Lunar New Year holiday, but this also led to an economic downturn. Moreover, the aerosol optical depth (AOD) decreased significantly. During the back-to-work period, the economy recovered and there was an increase in energy consumption, and CO2, NO2 emissions sharply increased to pre-lockdown levels. In the post-lockdown period, the AOD was lower than that of the same period last year. This study can provide reference for environmental policy making, as it demonstrates to what extent the control of pollution sources can improve air quality. Precise emission reduction and regional joint prevention and control are important and effective means for the prevention and control of O3 pollution. The health and economic benefits of COVID-19 pandemic control measures are incalculable. And this can provide an effective scientific basis and theoretical support for the prevention and control of air pollution.

Facile synthesis of nanosized Mn3O4 powder anodes for high capacity Lithium-Ion battery via flame spray pyrolysis.

Mn3O4 powders with nanometer size are successfully synthesized by a simple one-step method via flame spray pyrolysis. The precursor droplet is generated by heating under high temperature flame with fixed flow rate, and the exothermic reaction is induced to form nanosized Mn3O4 powders. When used as anode material for lithium-ion battery, the Mn3O4 exhibits good cycling capacity and rate performance. It delivers a specific capacity of 1,182 mA h g-1 over 110 cycles at a current density of 200 mA g-1, and has a high capacity of 140 mA h g-1 at 5,000 mA g-1.

Factors Affecting the Detection of Hexavalent Chromium in Cr-Contaminated Soil.

The alkali digestion pretreatment method in the United States Environmental Protection Agency (USEPA) Method 3060A could underestimate the content of Cr(VI) in Cr-contaminated soils, especially for soils mixed with chromite ore processing residue (COPR), which leads to a misjudgment of the Cr(VI) level in soils after remediation, causing secondary pollution to the environment. In this study, a new pretreatment method to analyze Cr(VI) concentration in contaminated soils was established. The impacts of soil quality, particle size, alkali digestion time and the rounds of alkali digestion on Cr(VI) detection in contaminated soils was explored and the alkali digestion method was optimized. Compared with USEPA Method 3060A, the alkaline digestion time was prolonged to 6 h and multiple alkali digestion was employed until the amount of Cr(VI) in the last extraction was less than 10% of the total amount of Cr(VI). Because Cr(VI) in COPR is usually embedded in the mineral phase structure, the hydration products were dissolved and Cr(VI) was released gradually during the alkaline digestion process. The amount of Cr(VI) detected showed high correlation coefficients with the percentage of F1 (mild acid-soluble fraction), F2 (reducible fraction) and F4 (residual fraction). The Cr(VI) contents detected by the new alkaline digestion method and USEPA Method 3060A showed significant differences for soil samples mixed with COPR due to their high percentage of residual fraction. This new pretreatment method could quantify more than 90% of Cr(VI) in Cr-contaminated soils, especially those mixed with COPR, which proved to be a promising method for Cr(VI) analysis in soils, before and after remediation.

WS2 significantly enhances the degradation of sulfachloropyridazine by Fe(III)/persulfate.

The use of antibiotics has become an indispensable part of the production and life of human society. Among them, sulfonamide antibiotics widely used in humans and animals are considered to be one of the most crucial antibiotics. However, antibiotics are difficult to degrade naturally, leading to an accumulation in the environment and a potential hazard to human health. In this paper, WS2 as a co-catalyst could reduce trace Fe(III) to Fe(II) which exhibited a great activating ability to PS through the exposed W(IV) active sites, and formed the Fe(III)/Fe(II) cycle to degrade sulfachloropyridazine (SCP) continuously. This paper systematically discussed the degradation of SCP under different conditions in the PS/WS2/Fe(III) system, including the amount of WS2, Fe(III) concentration, PS concentration, initial pH, natural organic matter (NOM) and common anions (NO3-, Cl-, HCO3-, HPO42- and H2PO4-). The experimental results showed that PS/WS2/Fe(III) system possessed a strong degradation ability for SCP in a wide pH range. NO3- and Cl- could promote the degradation of SCP a little. HCO3-, HPO42- and H2PO4- could significantly inhibit the degradation of SCP. The main types of free radicals that degraded SCP were explored. In addition, the stability and reusability of WS2 were examined, and two possible degradation pathways of SCP were proposed.

A poly (glycerol-sebacate-acrylate) nanosphere enhanced injectable hydrogel for wound treatment.

Wound repair remains a huge clinical challenge, which can cause bleeding, infection, and patient death. In our current research, a bioactive, injectable, multifunctional composite hydrogel doped with nanospheres was prepared with antibacterial and angiogenesis-promoting functions for the treatment of wounds. Amino groups in ε-polylysine (ε-EPL) undergo dynamic Schiff base reaction cross-linking with oxidized hyaluronic acid (OHA), and F127 exhibits unique temperature sensitivity to form an injectable thermosensitive hydrogel (FHE10), which can form a hydrogel to cover the wound at body temperature. Nanospheres (PNs) prepared using poly (glyceryl-sebacate-acrylate) (PGSA) were loaded into hydrogels (FHE10) for promoting wound repair. The prepared FHE10 exhibited rapid gelation, good injectable abilities, and showed resistance to the flourish of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). In vitro investigations showed that FHE10 had good hemocompatibility and cytocompatibility. FHE10@PNs exhibited good proliferation, migration, and tube formation of human umbilical vein endothelial cells (HUVECs) and human foreskin fibroblasts (HFF-1). Furthermore, FHE10@PNs significantly promoted reepithelialization and collagen deposition as well as micro-vascularization compared with the use of FHE10 or PNs alone, thereby accelerating the repair of wounds. In general, this study demonstrated that the multifunctional injectable composite hydrogel showed great potential in wound treatment.

Arsenite (III) removal via manganese-decoration on cellulose nanocrystal -grafted polyethyleneimine nanocomposite.

The manganese is successfully induced as a "bridge joint" to fabricate a new adsorbent (CNC-Mn-PEI) connecting cellulose nanocrystal (CNC) and polyethyleneimine (PEI) respectively. It was used to remove As (III) from waste water. It has been proved that the incompact CNC and PEI were successfully connected by Mn ions, which induced the formation of O-Mn-O bonds and the removal efficiency is maintained in the broad pH range of 4-8, even with the influence of NO3- and CO32-. The CNC-Mn-PEI was characterized by Brunauer-Emmett-Telley (BET) method and the results showed that the nanoparticle of the specific surface area was 106.5753 m2/g, it has a significant improvement, compared with CNC-Mn-DW (0.1918 m2/g). The isotherm and kinetic parameters of arsenic removal on CNC-Mn-PEI were well-fitted by the Langmuir and pseudo-second-order models. The maximum adsorption capacities toward As (III) was 78.02 mg/g. After seven regeneration cycles, the removal of As (III) by the adsorbent decreased from 80.78% to 68.2%. Additionally, the hypothetical adsorption mechanism of "bridge joint" effect was established by FTIR and XPS, which provided the three activated sites from CNC-Mn-PEI can improve the arsenic removal efficiency, and providing a new stratagem for the arsenic pollution treatment.

Recyclable nitrogen-doped biochar via low-temperature pyrolysis for enhanced lead(II) removal.

Facile and low-cost preparation are essential in the conversation of agricultural waste into biochar. In this work, nitrogen-doped biochar (NBC-350-0.1) was prepared by thermal decomposition of urea (urea/biochar = 0.1:1 mass ratio) at a low temperature of 350 °C. NBC-350-0.1 showed good performance for Pb(II) removal with the maximum adsorption capacity of 130.87 mg g-1 at 25 °C, which was five times that of pristine biochar (BC). Adsorption kinetics, isotherms and thermodynamics studies indicated that the adsorption of Pb(II) by NBC-350-0.1 or BC was the homogeneous monolayer adsorption with chemical action as the rate-limiting step, and was accompanied by spontaneous endothermic. Further analysis showed that the removal of Pb(II) on NBC-350-0.1 and BC depended on the complexation with unsaturated carbon bonds and ion exchange with Ca(II). Moreover, graphitic- and pyridinic-N in NBC-350-0.1 exerted a key part in the adsorption of Pb(II). NBC-350-0.1 regenerated by NaOH exhibited excellent recycling performance keeping the original removal efficiency at 84% after five cycles. In addition, this N doping method is suitable for improving the performance of coffee grounds, sawdust, and bagasse biochar. These results would provide an idea for obtaining recyclable N-doped biochar to treat the Pb(II) polluted wastewater.

Removal of natural organic matter by cationic hydrogel with magnetic properties.

Magnetic cationic hydrogel (MCH) was synthesized, and its removal efficiency and mechanisms in regard to natural organic matter (NOM, represented by humic acid and fulvic acid) from the aqueous environment were studied. The effects of time, adsorbent dosage, initial pH, ionic strength, background ions, and NOM types were also investigated. MCH was characterized and found to have a strong magnetic character, yielding an extra advantage for recycling and reuse. Batch studies showed that the removal of Aldrich humic acid (AHA) by MCH was effective. The main mechanism for the removal of NOM is believed to be due to electrostatic interaction. NOM with larger molecular weight tended to be preferentially removed. Solutions with low pH, high ionic strength, and background electrolytes containing calcium, sulfate and bicarbonate were unfavorable for AHA removal. The adsorption-desorption of MCH was evaluated in three cycles, and demonstrated high regeneration rates.