D-Band Center Optimization of Edge-Rich Ultrathin RuZn Nanosheets With Moiré Superlattices for pH-Universal Hydrogen Evolution Reaction.

Electrocatalytic hydrogen evolution reaction (HER) is a promising way to produce pure and clean hydrogen. However, the preparation of efficient and economical catalysts for pH-universal HER remains a challenging but rewarding task. Herein, ultrathin RuZn nanosheets (NSs) with moiré superlattices and abundant edges are synthesized. The RuZn NSs with unique structure exhibit superb HER performance with overpotentials of 11, 13, and 29 mV to achieve 10 mA cm-2 in 1 M KOH, 1 M PBS, and 0.5 M H2 SO4 , respectively, which is substantially lower than those of Ru NSs and RuZn NSs without moiré superlattices. Density functional theory investigations reveal that the charge transfer from Zn to Ru will lead the appropriate downshift of the d-band center of surface Ru atoms, thus accelerating hydrogen desorption from the Ru sites, lowering the dissociation energy barrier of water and greatly improving the HER performance. This work provides an effective design scheme for high-performance HER electrocatalysts over a wide pH range, and propose a general route to prepare Ru-based bimetallic nanosheets with moiré superlattices.

Fabrication, characterization and in vitro evaluation of triboelectric nanogenerator based on 317 L stainless steel and polylactic acid.

A novel, cost-effective biomedical triboelectric nanogenerator (TENG) has been fabricated based on biocompatible medical 317 L stainless steel (317 L SS) and polylactic acid (PLLA) films as the friction layers, whose surface roughness was designed by simple and low-cost laser etching and hot-embossing template methods, respectively. With the increase of the TENG's tribo-interface roughness and the molecular weight of the PLLA, the power output of TENG was greatly increased owing to more charges being produced and the excellent mechanical properties PLLA possessed. When the 317 L SS plate surface roughness was 66.54% measured by the image J software and the PLLA film with a larger molecular weight at 500 000 was patterned with the 1000 mesh screen template, the maximal short current, open voltage and transferred charge of TENG reached up to 60 µA, 150 V and ∼125 nC, respectively. At the optimum condition, the maximum instantaneous power of the TENG was 5.5 mW at a load resistance of ∼2.5 MΩ and the saturation voltage was 20 V when the load capacitance was 0.1 µF. The evaluation of the TENG's biocompatibility in vitro was performed by using the simulated body fluid (SBF) solution and ultrasonic wave to mimic the body environment with various vibrations, respectively. After 6 h ultrasonic bath for the directly immersed TENG, the pH of the SBF solution just changed slightly from 7.4 to 7.61 with an acceptable degradation of the output power of TENG. The cellular toxicity test also demonstrates that the mouse L929 cells grow excellently with normal morphology even after 5 d. These results indicate that the TENG has a good stability in the body environment and the output performance can still drive many micro-medical devices.

Research on Transmission Line Voltage Measurement Method of D-Dot Sensor Based on Gaussian Integral.

D-dot sensors meet the development trend towards the downsizing, automation and digitalization of voltage sensors and is one of research hotspots for new voltage sensors at present. The traditional voltage measurement system of D-dot sensors makes possible the reverse solving of wire potentials according to the computational principles of the electric field inverse problem by measuring electric field values beneath the transmission line. Nevertheless, as it is limited by the solving method of the electric field inverse problem, the D-dot sensor voltage measurement system is struggling with solving difficulties and poor accuracy. To solve these problems, this paper suggests introducing a Gaussian integral into the D-dot sensor voltage measurement system to accurately measure the voltage of transmission lines. Based on studies of D-dot sensors, a transmission line voltage measurement method based on Gaussian integrals is proposed and used for the simulation of the electric field of a 220 kV and a 20 kV transmission line. The feasibility of the introduction of the Gaussian integral to solve transmission line voltage was verified by the simulation results. Finally, the performance of the Gaussian integral was verified by an experiment using the transmission line voltage measurement platform. The experimental results demonstrated that the D-dot sensor measurement system based on a Gaussian integral achieves high accuracy and the relative error is lower than 0.5%.

Fabrication of hollow ZnO particles and its photocatalytic property by modifying of nano ZnS.

Large scale hollow ZnO spheres were prepared by a solvothermal method with the help of the solvent. And ZnS nanoparticles were successfully fabricated on the surface of ZnO via a hydrothermal process. These heterostructured ZnO/ZnS core/shell particles are around 1-2 microm in diameter, the ZnS shell formed on the surface of hollow ZnO sphere is comprise of the primary crystals about 30 nm in diameter. The products prepared were characterized by field emission scanning electron microscope (FE-SEM), X-ray powder diffraction (XRD), transmission electron microscope (TEM), and photo-luminescence spectroscope (PL). Theoretical calculation and experimental results have demonstrated that the combination of ZnO and ZnS (two wide band gap semiconductors) could yield a novel material with the photoexcitation threshold energy lower than the individual components. The electron transfers between ZnO core and ZnS shell, which strongly affect the photoluminescence and photocatalytic performances. The photocatalytic activities of the products were evaluated by methyl orange degradation as a probe reaction. The relationship of ZnO/ZnS core/shell particles as excellent photocatalyst could be anticipated.

Regenerated cellulose/chitosan composite aerogel with highly efficient adsorption for anionic dyes.

A novel reusable, high-compressible cotton regenerated cellulose/chitosan composite aerogel (RC/CSCA) was prepared using N-methylmorpholine-N-oxide (NMMO) as the green cellulose solvent, and glutaraldehyde (GA) as the crosslinking agent. The regenerated cellulose obtained from cotton pulp could chemically crosslink with chitosan and GA, to form a stable 3D porous structure. The GA played an essential role in preventing shrinkage and preserving the deformation recovery ability of RC/CSCA. Due to the ultralow density (13.92 mg/cm3), thermal stability (above 300 °C), and high porosity (97.36 %), the positively charged RC/CSCA can be used as a novel biocomposite adsorbent for effective and selective removal of toxic anionic dyes from wastewater, showing an excellent adsorption capacity, environmental adaptability, and recyclability. The maximal adsorption capacity and removal efficiency of RC/CSCA for methyl orange (MO) was 742.68 mg/g and 95.83 %.

Natural microfibrils/regenerated cellulose-based carbon aerogel for highly efficient oil/water separation.

Cellulose-based carbon aerogels as biodegradable and renewable biomass materials have presented potential applications in oil/water separation. Herein, a novel carbon aerogel composed of natural microfibrils/regenerated cellulose (NM/RCA) was directly prepared by economical hardwood pulp as raw material using a novel co-solvent composed of deep eutectic solvent (DES) and N-methyl morpholine-N-oxide monohydrate (NMMO·H2O). In addition, the morphology and structure of the filiform natural microfibers could be remained after carbonized at 400 â„ƒ, which resulted in a low density (8-10 mg cm-3), high specific surface area (768.89 m2 g-1) and high sorption capability. In addition, the aerogel exhibited high compressibility, outstanding elasticity, excellent fatigue resistance, and recyclability (80.5% height recovery after repeating 100 cycles at the strain of 80%). Due to the morphology and composition of the carbonized microfiber surface, the superhydrophobic materials with a water contact angle of 151.5°, could sorb various oils and organic solvents with 65-133 times its own weight and maintain 91.9% sorption capacity after 25 cycles. In addition, the aerogels could achieve the continuous separation of carbon tetrachloride (CCl4) from water with a high flux rate of 11,718.8 L m-2 h-1. Therefore, our prepared NM/RCA aerogels are anticipated to have broad potential applications in oil purification and contaminant remediation.

[Classification of plastics with laser-induced breakdown spectroscopy based on principal component analysis and artificial neural network model].

The classification of seven kinds of plastic (ABS, PET, PP, PS, PVC, HDPE and PMMA) with the laser-induced breakdown spectroscopy based on artificial neural network model was investigated in the present paper. One hundred seventy LIBS spectra for each type of plastic were collected. Firstly, all 1 190 plastics LIBS spectra were studied with principal component analysis. The first five principal components (PC) totally explain 78.4% of the original spectrum information. Therefore, the scores of five PCs of 130 LIBS spectra for each kind of plastic were chosen as the training set to build a back-propagation artificial network model. And the other 40 LIBS spectra of each sample were used as the testing set for the trained model. The classification accuracy was 97.5%. Experimental results demonstrate that plastics can be classified by using principal component analysis and artificial neural network (BP) method.

Efficient Electrooxidation of 5-Hydroxymethylfurfural Using Co-Doped Ni3 S2 Catalyst: Promising for H2 Production under Industrial-Level Current Density.

Replacing oxygen evolution reaction (OER) by electrooxidations of organic compounds has been considered as a promising approach to enhance the energy conversion efficiency of the electrolytic water splitting proces. Developing efficient electrocatalysts with low potentials and high current densities is crucial for the large-scale productions of H2 and other value-added chemicals. Herein, non-noble metal electrocatalysts Co-doped Ni3 S2 self-supported on a Ni foam (NF) substrate are prepared and used as catalysts for 5-hydroxymethylfurfural (HMF) oxidation reaction (HMFOR) under alkaline aqueous conditions. For HMFOR, the Co0.4 NiS@NF electode achieves an extremely low onset potential of 0.9 V versus reversible hydrogen electrode (RHE) and records a large current density of 497 mA cm-2 at 1.45 V versus RHE for HMFOR. During the HMFOR-assisted H2 production, the yield rates of 2,5-furandicarboxylic acid (FDCA) and H2 in a 10 mL electrolyte containing 10 × 10-3 M HMF are 330.4 µmol cm-2 h-1 and 1000 µmol cm-2 h-1 , respectively. The Co0.4 NiS@NF electrocatalyst displays a good cycling durability toward HMFOR and can be used for the electrooxidation of other biomass-derived chemicals. The findings present a facile route based on heteroatom doping to fabricate high-performance catalyses that can facilitate the industrial-level H2 production by coupling the conventional HER cathodic processes with HMFOR.

Roles of membrane-foulant and inter/intrafoulant species interaction forces in combined fouling of an ultrafiltration membrane.

To explore better the combined organic-inorganic fouling mechanisms of ultrafiltration (UF) membranes, SiO2 and bovine serum albumin (BSA), humic acid (HA) were chosen as model inorganic and organic foulants, respectively. Fouling experiments with single and combined foulants, corresponding fouling layer structure, and the membrane-foulant and inter/intrafoulant species interaction forces were investigated. The results showed that the addition of SiO2 particles led to opposite fouling phenomena for BSA and HA, which could be explained by the membrane-foulant and interfoulant species interaction forces. In the initial filtration stage, the combined fouling behavior was related to the relative strength of the interaction forces of membrane with both inorganic and organic foulant. Specifically, when the SiO2-membrane interaction force>organic-membrane interaction force, the combined fouling would be enhanced with the addition of SiO2 particles; otherwise, it would be mitigated. In the later filtration stage, the combined fouling was related to the inorganic-organic interaction forces. Thus, the stronger SiO2-BSA interaction force led to the formation of large SiO2-BSA aggregates, which resulted in a more porous fouling layer and higher hydraulic permeability. In contrast, the negligible SiO2-HA interaction forces caused the SiO2 particles to fill uniformly in or between the HA molecules, which resulted in a more compact fouling layer and more serious membrane fouling.

[Purification Efficiency and Mechanism of Integrated Al Salt Floc-ultrafiltration Membrane Process].

Owing to the small land use and high pollutant removal efficiency, the integrated ultrafiltration (UF) membrane process has been gradually applied in water treatment. However, not only would the membrane surface be damaged by the commonly used granular adsorbents over time, but these types of adsorbents are expensive, such as nano zerovalent iron, carbon nanotubes, etc. To overcome these disadvantages, the loose Al-based flocs were directly injected into the membrane tank in the presence of humic acid and Miyun reservoir water. Results showed that severe membrane fouling was induced by HA alone, and the transmembrane pressure (TMP) significantly increased to 76.4 kPa after 12 d of operation. However, it dramatically decreased to 10.1 kPa after washing with tap water on day 13, indicating that the cake layer was the main fouling mechanism. The average HA removal efficiency was only 23.3% during filtration. In addition, the performance of the integrated flocs-membrane process could be influenced by floc dosage, injection frequency, and solution pH. The integrated membrane performed well with flocs (43.2 mmol·L-1) continuously injected at pH 6.0 (aeration rate at 0.3 L·min-1). The corresponding TMP only increased to 19.5 kPa after running for 12 d, which decreased to 5.6 kPa after washing with tap water on day 13. The average HA removal efficiency increased to 61.2%. Additionally, serious membrane fouling was also induced by Miyun reservoir alone. The TMP increased to 38.0 kPa on day 12, while it decreased to 3.8 kPa after washing with tap water on day 13. The cake layer was also the main fouling mechanism, and the average pollutant removal efficiency was only 7.5%. With floc continuously injected, however, the TMP only increased to 6.1 kPa on day 12. After washing with tap water, the TMP decreased to 2.3 kPa on day 13, and the average pollutant removal efficiency was as high as 58.6%. Based on the excellent membrane performance, the integrated membrane process exhibited potential application in drinking water treatment.

[Removal Efficiency and Mechanism of Removal by Humic Acid of the Integrated Floc-ultrafiltration Process].

In recent years, the integrated ultrafiltration (UF) membrane process has been widely used due to its high removal efficiency, slight membrane fouling, and small land use. However, a number of problems gradually occurred regarding the integrated UF process caused by the granular adsorbents used, such as powdered activated carbon, carbon nano-tube, nanoscale zerovalent iron, etc. Severe membrane surface damage was easily caused by these granular adsorbents after a long running time, and the cost of most adsorbents was very high. In this study, to effectively overcome these problems, cheap and loose aluminum hydrolyzed flocs were directly injected into the membrane tank in the presence of humic acid (HA), with the aim of investigating the removal efficiency of HA and the corresponding membrane behavior. The results showed that the removal efficiency of HA could be influenced by aeration mode, floc injection frequency, and floc dosage. Compared with intermittent aeration and one-time injection, a loose "protection membrane" layer was formed with continuous aeration and batch injections. Therefore, HA molecules were largely removed, leading to the dramatic alleviation of membrane fouling. The transmembrane pressure significantly increased to 74.8 kPa in the absence of flocs after running for 5 days, but that only increased by 6.3 kPa with continuous aeration and an injection frequency of once every 2 d (each addition consisted of 5.4 mmol·L-1 flocs) after running for 8 days. The removal efficiency of HA was 73.3% (8 d), which was much higher than in the absence of flocs (5 d, 32.1%). Additionally, only a few HA molecules were adsorbed onto the membrane pores with the batch injections, and a loose cake layer was the main fouling mechanism. With higher dosages of flocs injected each time, the average membrane pore diameter was larger after washing. Based on this excellent performance, this floc-integrated UF membrane technology indeed shows large application potential in water treatment.

Ultrafiltration membrane fouling induced by humic acid with typical inorganic salts.

Severe ultrafiltration (UF) membrane fouling is always induced by humic acid (HA). However, little attention has been paid to the influence of inorganic salts, and even the studies related have been limited to only a single kind of salt. In addition, the concentration of the inorganic salts reported in previous studies is much high. Herein, the effect of HA on UF membrane performance was investigated in the presence of typical inorganic salts, with concentrations similar to those in natural waters or actually used in most current water plants. The results showed that membrane performance was influenced little by monovalent inorganic salts (NaCl and KCl), while divalent inorganic salts (CaCl2 and MgCl2) could exacerbate the membrane fouling. For trivalent inorganic salts (AlCl3·6H2O and FeCl3·6H2O), floc adsorption was the dominant HA removing mechanism, and AlCl3·6H2O behaved better than FeCl3·6H2O. Relating to the floc properties, severe membrane fouling occurred with low dosage, while it was mitigated with high dosage. Compared with the trivalent inorganic salts, more severe membrane fouling was caused by divalent inorganic salts. Additionally, little synergistic or inhibitory effect occurred with mixtures of divalent inorganic salts and trivalent inorganic salts. Furthermore, analysis with the classical fouling models showed that cake filtration was the main fouling mechanism with/without inorganic salts. Based on the findings, we believe these different HA behaviors exhibited during coagulation process with inorganic salts will have a large potential application in UF membrane fouling alleviation in water treatment.

Moderate KMnO4-Fe(II) pre-oxidation for alleviating ultrafiltration membrane fouling by algae during drinking water treatment.

Although ultrafiltration (UF) membranes are highly beneficial for removing algae, the removal process causes serious UF membrane fouling. To avoid the unfavorable effects of algal cells that have been damaged by oxidants, our previous study reported a novel, moderate pre-oxidation method (KMnO4-Fe(II) process) that aimed to achieve a balance between the release of intracellular organic matter and enhanced algae removal. This study further investigated the performance of a UF membrane with KMnO4-Fe(II) pretreatment in the presence of algae-laden reservoir water after a long running time. We found that algae could be completely removed, membrane fouling was significantly alleviated, and the overall performance was much better than that of Fe(III) coagulation alone. The transmembrane pressure (TMP) during Fe(III) coagulation increased to 42.8 kPa, however, that of the KMnO4-Fe(II) process only increased to 25.1 kPa for after running for 90 d. The slower transmembrane pressure was attributed to the larger floc size, higher surface activity, and inactivation of algae. Although there was little effect on microorganism development, lower microorganism abundance (20.7%) was observed during the KMnO4-Fe(II) process than during coagulation alone (44.9%) due to the release of extracellular polymeric substances. We also found that the floc cake layer was easily removed by washing, and many of the original membrane pores were clearly observed. Further analysis demonstrated that the effluent quality was excellent, especially its turbidity, chromaticity, and Mn and Fe concentrations. Based on the outstanding UF membrane performance, it may be concluded that the KMnO4-Fe(II) process exhibits considerable potential for application in the treatment of algae-laden water.

Multiple dynamic Al-based floc layers on ultrafiltration membrane surfaces for humic acid and reservoir water fouling reduction.

The integration of adsorbents with ultrafiltration (UF) membranes is a promising method for alleviating membrane fouling and reducing land use. However, adsorbents typically are only injected into the membrane tank once, resulting in a single dynamic protection layer and low removal efficiency over long-term operation. In addition, the granular adsorbents used can cause membrane surface damage. To overcome these disadvantages, we injected inexpensive and loose aluminum (Al)-based flocs directly into a membrane tank with bottom aeration in the presence of humic acid (HA) or raw water taken from the Miyun Reservoir (Beijing, China). Results showed that the flocs were well suspended in the membrane tank, and multiple dynamic floc protection layers were formed (sandwich-like) on the membrane surface with multiple batch injections. Higher frequency floc injections resulted in better floc utilization efficiency and less severe membrane fouling. With continuous injection, acid solutions demonstrated better performance in removing HA molecules, especially those with small molecular weight, and in alleviating membrane fouling compared with the use of high aeration rate or polyacrylamide injection. This was attributed to the small particle size, large specific surface area, and high zeta potential of the flocs. Additionally, excellent UF membrane performance was exhibited by reservoir water with continuous injection and acid solution. Based on the outstanding UF membrane performance, this innovative integrated filtration with loose Al-based flocs has great application potential for water treatment.

[Community Structure and Activity Analysis of the Nitrifiers in Raw Sewage of Wastewater Treatment Plants].

The communities and activity of nitrifiers collected from the raw sewage of the 2nd and 3rd wastewater treatment plants (WWTP) in Xi'an were investigated. FISH results indicated that the (AOB+NOB)/EUB percentages were (5.35±2.1)% and(6.0±2.8)% in the 2nd and 3rd WWTP, respectively. The dominant AOB was Nitrosomonas europaea/Nitrosococcus mobilis lineage and the dominant NOB was Nitrospira, the sub-dominant NOB was Nitrobacter, and coexisted with Nitrococcus, Nitrospina. Respirometric assays showed that the influent nitrifiers were active following a 2-16 hour period of metabolic induction. The ammonium utilized rate was (0.32±0.12) mg·(L·h)-1 and (0.43±0.17) mg·(L·h)-1, nitrite utilized rate was (0.71±0.18) mg·(L·h)-1 and (0.58±0.27) mg·(L·h)-1 for nitrifers in raw sewage fed to the 2nd and 3rd WWTP, respectively. Therefore, nitrifiers were present and active in the raw sewage, and played the role of natural continuous seeding in the activated sludge system. Based on the nitrification activity, the estimated continuous seeding intensity of AOB and NOB was 0.08-0.09 g·(g·d)-1 and 0.11-0.24 g·(g·d)-1, respectively.

Synthesis of stable hollow silica microspheres with mesoporous shell in nonionic W/O emulsion.

Stable hollow silica microspheres were synthesized by a solgel method in nonionic W/O emulsion; the mesoporous shell wall of the spheres could have potential applications as controlled release capsules for drugs, dyes, cosmetics and inks, artificial cells, catalysts, and fillers.

Synthesis of silica nanotubes from kaolin clay.

Silica nanotubes were synthesized from kaolin clay using surfactant intercalation, sulfuric acid and hydrothermal treatments.

Influence of the Al source and synthesis of ordered Al-SBA-15 hexagonal particles with nanostairs and terraces.

We investigated the effect of various aluminum sources on the morphology and microstructure of nanoporous Al-SBA-15. With aluminum tri-sec-butoxide (Al-TSB), very large, ordered hexagonal rods of Al-SBA-15 covered by nanostairs and terraces were synthesized. Such a morphology was not obtained with an inorganic Al source (sodium aluminate) or with organic sources seemingly similar to Al-TSB, such as aluminum tri-tert-butoxide, aluminum tri-n-butoxide, or aluminum isopropoxide. The results obtained from X-ray diffraction, scanning electron microscopy/transmission electron microscopy, N(2) adsorption/desorption, and high-performance (129)Xe NMR suggest that preparing an organic Al-Si precursor by premixing liquid organic Al and Si sources (Al-TSB and tetraethyl orthosilicate) is crucial in obtaining highly ordered mesoporous Al-SBA-15 materials with a well-defined morphology.