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Low-cost catalysts with high activity are in immediate demand for energy storage and conversion devices. In this study, polyvinyl pyrrolidone was used as a complexing agent to synthesize La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) perovskite oxide. The obtained porous layered LSCF has a large specific surface area of 23.74 m2/g, four times higher than that prepared by the traditional sol-gel method (5.08 m2/g). The oxygen reduction reaction activity of the oxide in 0.1 mol/L KOH solution was studied using a rotating ring-disk electrode. In the tests, the initial potential of 0.88 V (vs. reversible hydrogen electrode) and the limiting diffusion current density of 5.02 mA/cm2 were obtained at 1600 r/min. Therefore, higher catalytic activity and stability were demonstrated, compared with the preparation of LSCF perovskite oxide by the traditional method.

Biodegradable plastics have been increasingly used as a solution to the problem of plastic pollution in recent years. However, there are few studies on the negative effects of biodegradable microplastics. Triclosan, a widely used disinfectant, is a highly toxic substance. In the present study, the adsorption and desorption processes of triclosan on a type of biodegradable plastics, polyhydroxybutyrate (PHB), were investigated and also compared with one conventional plastic type, polyethylene. The adsorption equilibrium quantities of polyethylene and PHB were 3431.85 and 9442.27 μg/g, respectively. The adsorption rate and equilibrium adsorption capacity of triclosan on PHB are much higher than on polyethylene. Physical adsorption of triclosan on PHB and polyethylene microplastics may play a dominant role in this process. The desorption hysteresis indices are all less than zero; this indicates that triclosan is easily released from PHB and polyethylene microplastics under physiological conditions. Our results indicate that biodegradable PHB microplastics are stronger carriers for triclosan than the conventional polyethylene microplastics in the aquatic environment. Environ Toxicol Chem 2021;40:72-78. © 2020 SETAC.

In the recent years, microplastics have attracted much attention as new emerging environmental pollutants. Previously, several studies were performed to understand the source and fate of microplastics in the environment, organisms, and food webs. To track microplastics and improve their legibility, labeling them is a very effective method during laboratory experiments. This study presents an effective Rhodamine B dye (RhB) staining method for microplastics. The method is crucial for the visual observation of white or transparent plastics by dyeing them in purple or pink, as well as makes the microplastics to fluoresce under common microscope fluorescence filter ranges. Five types of microplastic polymers, namely polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyurethane were used as the test materials. The efficiencies of ethanol, acetone, and distilled water as possible solvents for dissolving RhB were investigated. Next, the fluorescence stability in various conditions was assessed. The results indicated that ethanol was the most appropriate solvent in dissolving RhB used in staining the microplastics. RhB was fluorescently stable under varying conditions (light and gut fluid) or different solutions (KOH, nitric acid, and saturated NaCl). Additionally, RhB staining exhibited an insignificant effect on the Raman spectra of the microplastics. Our proposed method is simple and robust and helps to visualize the different types of microplastic polymers tested in laboratory experiments, particularly the transparent, white, and small size microplastics.

There has been a growing concern about plastic pollution, both from a health and ecological perspective. One of the major concerns with plastic debris, especially microplastics (MPs) relates to their strong potential for releasing additives and chemicals. Di-2-ethylhexyl phthalate (DEHP) is a common plastic additive widely used as plasticizer in plastic products, and is of global concern due to its widespread contamination in the environment. In this study, two conventional nondegradable plastics (polyethylene (PE) bags and PE mulch) and two biodegradable plastics (poly(butylene adipate co-terephtalate)-starch-based-polylactic acid bags (PBAT/PLA bags) and PLA mulch) were selected to investigate the release of DEHP to seawater. The results showed that leaching potentials of DEHP from different types of MPs varied. Among the four selected MPs, PE mulch had the highest leaching potential (6.88 μg/g), followed by PE bags (4.24 μg/g), PLA mulch (1.10 μg/g) and PBAT/PLA bags (0.89 μg/g). The DEHP leaching kinetic curves of the four MPs were all in line with the pseudo first order model. The potential risk of environmental and human exposure to the leached DEHP was assessed using the average Phthalate Pollution Index (PPI). The calculated PPI indicated low pollution risks of DEHP released by the four MPs in seawater.

The use of biodegradable plastics may solve the pollution caused by conventional plastics in the future. However, microplastics and nanoplastics are produced during the aging process of biodegradable plastics. This work evaluated the formation of secondary microplastics and nanoplastics and the effects of aging factors (UV radiation and mechanical forces) during the degradation processes of various biodegradable plastics (poly(butylene adipate co-terephtalate) (PBAT), poly(butylene succinate) (PBS), and polylactic acid (PLA)) and conventional plastics (polyethylene (PE), polystyrene (PS), and polyvinyl chloride (PVC)). This study also assessed the combined toxicity of secondary microplastics and Triclosan (TCS) on Tigriopus japonicas. The results showed that PLA and PBS could produce many microplastics. Most secondary microplastics were smaller than 50 μm. Primary pellets were more likely to generate microplastics through mechanical degradation than via photooxidation. In contrast, PBAT/PLA and PE bags were more likely to form microplastics through photooxidation than mechanical degradation. The secondary microplastics did not affect the survival of T. japonicas and the toxicity of TCS. This study highlights that risk assessment of biodegradable plastics, especially secondary microplastics, and nanoplastics, should be assessed in future studies.

Respiratory diseases including apnea are often accompanied by abnormal respiratory depth, frequency, and rhythm. If different abnormal respiratory patterns can be detected and recorded, with their depth, frequency, and rhythm analyzed, the detection and diagnosis of respiratory diseases can be achieved. High-frequency millimeter-wave radar (76–81 GHz) has low environmental impact, high accuracy, and small volume, which is more suitable for respiratory signal detection and recognition compared with other contact equipment. In this paper, the experimental platform of frequency-modulated continuous wave (FMCW) radar was built at first, realizing the noncontact measurement of vital signs. Secondly, the energy intensity and threshold of respiration signal during each period were calculated by using the rectangular window, and the accurate judgment of apnea was realized via numerical comparison. Thirdly, the features of respiratory and heart rate signals, the number of peaks and valleys, the difference between peaks and valleys, the average and the standard deviation of normalized short-term energy, and the average and the standard deviation and the minimum of instantaneous frequency, were extracted and analyzed. Finally, support vector machine (SVM) and K-nearest neighbor (KNN) were used to classify the extracted features, and the accuracy was 98.25% and 88.75%, respectively. The classification and recognition of respiratory patterns have been successfully realized.

Transition metal/nitrogen carbon composite (M/NC) is a highly active oxygen reduction reaction (ORR) electrocatalyst, widely used in fuel cells and zinc-air batteries. Herein, a uniform and regular PVP-assisted iron-doped nano dodecahedron (ZP0.1F/NC) is prepared by a simple and efficient one-step in-solution reaction, followed by controlled in situ pyrolysis. The synthesized electrocatalyst showed excellent electrocatalytic ORR activity in an alkaline medium. Compared with standard 20% Pt/C electrocatalyst, ZP0.1F/NC exhibited onset potential (Eonset) (0.974 V vs 0.967 V), half-wave potential (E1/2) (0.861 V vs 0.857 V) and the limiting current density (jd) was 6.373 mA cm−2 vs 5.401 mA cm−2, also better than the Fe doped ZIF-8 nitrogen composite (ZF/NC), PVP auxiliary ZIF-8 (ZP0.1/NC) and pure ZIF-8 nitrogen composite (Z/NC) synthesized by the same procedure. In addition, the zinc-air battery assembled with ZP0.1F/NC also exhibits outstanding discharge capacity, with a specific capacity and energy density of 793.3 mAh g−1 and 974.9 Wh kg Zn − 1 , respectively, much higher than that of commercial 20% Pt/C-based zinc-air battery (719.8 mAh g−1, 842.6 Wh kg Zn − 1 ), indicating its great potential in practical energy conversion and storage.

Incorporating metal compound nanoparticles in carbonaceous matrix is a valid strategy to fabricate highly efficient oxygen reduction electrocatalysts. Herein, N, P-codoped carbon nanotubes embedded with Fe2P nanoparticles (Fe2P/NPCt) were synthesized in this work. Results show carbon nanotubes have a large specific surface area (987 m2 g−1) with an inner diameter of ∼60 nm. About 5.90 wt% nitrogen (35.18% pyridinic N) and 2.56 wt% phosphorus (mainly in the form of P–C and P–Fe) was doped in Fe2P/NPCt. HRTEM and XRD results confirmed the well dispersed Fe2P nanoparticles in 5 ∼10 nm on carbon nanotubes. The electrochemical performance of Fe2P/NPCt was evaluated in 0.10 M KOH using cyclic voltammetry, linear scanning voltammetry, and chronoamperometry. Fe2P/NPCt exhibits high electrocatalytic activity towards oxygen reduction with an onset potential of 1.029 V (vs RHE) and a limited current density of 6.79 mA cm−2, surpassing those of 20% Pt/C (0.950 V and 5.20 mA cm−2). Furthermore, Fe2P/NPCt presents outstanding durability and good methanol tolerance during long-term ORR. When assembled in a primary zinc-air battery (ZAB), the maximum power density and specific capacity of ZAB reach 175.48 mW cm−2 and 744.1 mAh g−1, respectively, outperforming ZAB equipped with 20% Pt/C.

A novel approach was proposed for the extraction of gallium from high-ferric and strongly acidic sulfate leach solutions from zinc refinery residue. The stepwise separation was carried out using N235 and Cyanex 272 in the first and second steps, respectively. The results showed that N235 could selectively remove iron and H2SO4 and provide suitable conditions for the subsequent extraction by Cyanex 272. The co-extracted zinc, gallium, and iron were separated by stepwise stripping. In batch tests, 97.9% of iron was selectively extracted from solutions through three-stage cross-current extraction by using an organic system consisting of 30% (v/v) N235 and 10% (v/v) tributyl phosphate in sulfonated kerosene with an aqueous/organic (A/O) ratio of 1:1, while the percentage extractions of other metals were 99.9% gallium, >99.9% remaining iron, and 49.7% zinc were co-extracted through four-stage counter-current extraction by using an organic system consisting of 30% (v/v) Cyanex 272 in sulfonated kerosene with an A/O ratio of 1:1, while the percentage extractions of other metals (copper and cadmium) were negligible (the separation factors of βGa/Zn, βGa/Fe, βGa/Cu, and βGa/Cd, were determined to be 6.1×103, 2.7×10-1, 3.3×106, and ∞, respectively). Furthermore, >99.9% zinc, 99.7% gallium, and 98.9% iron in the loaded organic system were efficiently separated through a stepwise stripping process by using 6 mol/L HCl, 0.5 mol/L H2SO4, and 0.6 mol/L H2C2O4 (the separation factors of βZn/Ga, βZn/Fe, and βGa/Fe, were determined to be 1.1×106, 4.4×104, and 6.4×104, respectively). Overall, 99.7% of gallium was separated and extracted into the strip liquor, resulting in a concentration of 1502 mg/L.

In this study, surface morphology, inner structure and phase composition of anodic layers on Pb-Ag anode in fluoride/chloride-containing H 2 SO 4 solutions were investigated in the presence/absence of Mn 2 + . Additionally, corrosion morphology of metallic substrate and anodic potential variation of Pb-Ag anodes were studied as well. The influence of Mn 2 + on the anodic layer property and corrosion behavior of Pb-Ag anodes in fluoride/chloride-containing H 2 SO 4 solutions was then clarified. The results revealed that in the presence of Mn 2 + , anodic layer consisted of an external layer in MnO 2 /PbO 2 -PbSO 4 /MnO 2 structure and an inner layer adhering to the metallic substrate. Due to the coverage of an external layer, the corrosion of metallic substrate was relieved by the presence of Mn 2 + in fluoride/chloride-containing H 2 SO 4 solution. As was demonstrated, Mn 2 + decreased PbO 2 concentration in the inner layer, especially in fluoride-containing solution. In the presence of Mn 2 + , the anodic potential was higher than that in solutions without Mn 2 + due to larger thickness and resistance of anodic layer. In addition, the anodic potential was characterized by oscillation in Mn 2 + -containing solution, indicating low stability of anodic layer. Comparatively, the anodic layer formed in the presence of Mn 2 + and chloride ion was more stable than that in solutions containing Mn 2 + and fluoride ion.

Microplastics as new emerging pollutants in aquatic environments have received much attention in recent years. However, up to now, microplastic contamination in tap water has only been investigated by few studies. Therefore, this study investigated the presence of microplastics in tap water. 38 tap water samples were taken at different cities of China. The amount of microplastics in tap water varied from 440 ± 275 particles L−1. Particles smaller than 50 μm significantly predominated in most of the tap water samples. Further, according to the shape of these particles, fragments, fibers and spheres were found in tap water samples, while fragments were the most abundant morphotype in most samples. Despite these particles were identified as 14 different materials by micro-Raman spectroscopy, the majority of the microplastics comprised of polyethylene and polypropylene. Based on this investigation, drinking water treatment plants seemingly have to face the problem of microplastic pollution in tap water due to their potential eco-toxicological effects on humans.

Transition metal phosphide/carbon composites are promising electrocatalysts for oxygen reduction reaction (ORR). Herein, we propose a facile process to fabricate a bayberry-like N, P-enriched carbon nanospheres embedded with Fe2P nanocrystals (Fe2P/NPCs). Bayberry-like polyaniline nanospheres (PANI-NS) are firstly synthesized through microemulsion template method. Then, Fe is incorporated in PANI-NS during the hydrothermal treatment. Lastly FexP nanocrystals and N, P-enriched carbonaceous carriers are obtained by pyrolyzing the hydrothermal-treated PANI-NS. The resultant FexP/NPCs exhibit a uniform particle size (~250 nm), a large specific surface area (523 m2 g−1) and a homogeneous mesoporous structure (~3.46 nm). The phase structure of FexP depends on the Fe/P (molar ratio) during hydrothermal treatment. When Fe/P is around 0.2, a preferable Fe2P phase is obtained. The Fe2P/NPCs exhibit outstanding ORR electrocatalytic activity with a half-wave potential of 0.820 V (vs. RHE) and a diffusion-limited current density of 5.58 mA cm−2, comparable with commercial Pt/C. Moreover, Fe2P/NPCs possess a good duration stability and higher methanol tolerance than commercial Pt/C. When assembled in zinc-air batteries, Fe2P/NPCs contribute to an open circuit voltage of 1.449 V, a maximum power density of 128.38 mW cm−2, and a specific capacity of 691.0 mAh g−1, superior to the commercial Pt/C-based zinc-air battery.

The nonferrous metal electrowinning process is energy intensive due to the sluggish dynamics of the oxygen evolution reaction (OER) on the anode. Developing novel anode materials with high OER activity and stability is imperative. Herein, we propose a novel Pb-ceramic composite anode by introducing ZnFe2O4. In this work, Pb-ZnFe2O4 and PS-Pb anodes were prepared through powder pressing and sintering processes. The effects of ZnFe2O4 particles on the phase composition, surface morphology and inner structure of the oxide layer formed on Pb-ZnFe2O4 anodes were investigated. Furthermore, the role of ZnFe2O4 in the anodic potential and stability of Pb-ZnFe2O4 anodes was discussed. The results show that as the ZnFe2O4 content increases, the oxide layer formed on Pb-ZnFe2O4 anodes exhibits higher surficial compactness, higher integrity, and much smaller thickness. ZnFe2O4 exhibits a trivial impact on the oxygen evolution dynamics. However, the anodic potential of the Pb-ZnFe2O4 anode declines as the ZnFe2O4 content increases, which could be attributed to the higher compactness and smaller thickness of the oxide layer. As the ZnFe2O4 content increases, the weight loss of the Pb-ZnFe2O4 composite anode increases, suggesting the unsatisfactory stability of Pb-ZnFe2O4, which could be attributed to the inevitable dissolution of ZnFe2O4 particles, smaller thickness of the oxide layer and larger porosity of the substrate. Although Pb-ZnFe2O4 composite anodes have the potential to reduce energy consumption, their unsatisfactory stability limits the feasibility of Pb-ZnFe2O4 anodes in the electrowinning industry.

In this work, the surface morphology, inner structure and phase composition of the oxide layers formed on Pb and pyramid-shaped 3D-Pb (Pyra-Pb) anodes after different periods of galvanostatic polarization were investigated. The results showed that in the preliminary stage, the lead compounds and MnO2 deposited at a higher rate on the Pyra-Pb anode. The deposited MnO2 layer on the Pyra-Pb anode was compact and well adhered, while that on the Pb anode exhibited a loose and porous structure. After a longer period of galvanostatic polarization, the oxide layer on the Pyra-Pb anode exhibited a higher stability due to its smaller thickness, denser surface structure and higher physical stability of the inner MnO2 layer. Consequently, the potential-time curve of the Pyra-Pb anode was smooth, while that of the Pb anode presented an oscillatory character with potential spikes and steps. Furthermore, the performance of the Pyra-Pb anode during 72 h of galvanostatic electrolysis was evaluated and compared with that of the Pb anode. The results showed that in the presence of 4 and 6 g L−1 Mn2+, the average anodic potentials of the Pyra-Pb anode were approximately 70 mV and 100 mV lower than those of the Pb anode, respectively. The lower potentials could be explained by the lower ohmic resistance of the MnO2 layer due to its denser structure and smaller thickness. It was also found that the Pyra-Pb anode significantly reduced the mass of the cell sludge, which could be attributed to the higher stability of the MnO2 layer and lower Mn3+ concentration in the electrolyte. In summary, it was demonstrated that the Pyra-Pb anode has a great potential to reduce the energy consumption and cell sludge of the zinc electrowinning process.

In this paper, a classical blind source separation (BSS) method is applied to optical imaging of intrinsic signals for separation of arteries and veins in the cerebral cortex. The separation method is based on the fact that the physiological sources are different between arterial regions and venous regions. After segmenting the vascular network, independent component analysis (ICA) was applied to the vascular images for separating the mixed sources into independent components. We selected heartbeat corresponding time course, then founded coherence with every pixel time course at heartbeat frequency. The resulting value constructed a new heartbeat corresponding feature map. A new respiration corresponding feature map was obtained in the same way. Two feature maps were combined as feature vector for the fuzzy c-means clustering method. Determination of vessel type was conducted on each vessel segments divided by morphological intersection points. Finally, it was able to separate arteries and veins by optical gray image of intrinsic signal.