镁改性活性炭强化活性污泥处理混合污水研究

基于序批式活性污泥法(SBR)工艺,将镁盐改性活性炭(MgO-PAC)与传统活性炭(PAC)混合而成MPAC材料,用于处理生活与工业混合污水。通过连续30 d的运行实验,探讨了MPAC材料对生活与工业混合污水中COD、NH4^+-N和TP的去除效果以及对污泥的比耗氧速率、沉降性能和微生物多样性的影响。结果表明,投加MPAC材料对污水中COD的去除率提升了12.7百分点,对TP的去除率提升了17.5百分点,对NH4^+-N的去除率超过86.4%。投加MPAC后处理效果更好的重要原因,在于MPAC使得活性污泥的沉降性能和比耗氧速率得到明显改善,也提升了污泥的微生物丰度。MPAC对活性污泥处理生活与工业混合污水具有强化作用。     

Two-step pyrolytic engineering to form porous nitrogen-rich carbons with a 3D network structure for Zn-air battery oxygen reduction electrocatalysis

It is of great urgency to design inexpensive and high-performance oxygen reduction reaction (ORR) electrocatalysts derived from biowastes as substitutes for Pt-based materials in electrochemical energy-conversion devices. Here we propose a strategy to synthesize three-dimensional (3D) porous nitrogen-doped network carbons to catalyze the ORR from two-step pyrolysis engineering of biowaste scale combined with the use of a ZnCl₂ activator and a FeCl₂ promotor. Electrochemical tests show that the synthesized network carbons have exhibited comparable ORR catalytic activity with a half-wave potential (~0.85 V vs. RHE) and outstanding cyclical stability in comparison to the Pt/C catalyst. Beyond that, a high electron transfer number (~3.8) and a low peroxide yield (<7.6%) can be obtained, indicating a four-electron reaction pathway. The maximum power density is ~68 mW cm^?2, but continuous discharge curves (at a constant potential of ~1.30 V) for 12 h are not obviously declined in Zn-air battery tests using synthesized network carbons as the cathodic catalyst. The formation of 3D porous structures with high BET surface area can effectively expose the surface catalytic sites and promote mass transportation to boost the ORR activity. This work may open a new idea to prepare porous carbon-based catalysts for some important reactions in new energy devices.     

Facile and efficient synthesis of magnetic fluorescent nanocomposites based on carbon nanotubes

Multifunctional nanomaterials composed of magnetic and fluorescent nanoparticles have been one of the most extensive pursuits because of the potential application in bio-research. In this paper, we demonstrated an efficient method by coupling CdSe/CdS/ZnS quantum dots (QDs) with Fe₃O₄ magnetic nanoparticles(MNPs) while functionalized multiwall carbon nanotubes (f-MWCNTs) were used as matrix to synthesize a kind of magnetic fluorescent nanocomposite. Compared with other matrix materials, carbon nanotubes have the advantages of high surface areas and good biocompatibility. The incorporation of f-MWCNTs supplies plenty of nucleation sites for the preferential growth of Fe₃O₄ nanoparticles, avoiding the agglomeration phenomenon of Fe₃O₄ MNPs in traditional co-precipitation method. Moreover, the un-reacted functional groups of f-MCNTs can further adsorb biological species and drugs, averting the decline of fluorescent intensity caused by the modification of biological species and drugs. The synthetic product maintains the unique properties of rapid magnetic response and efficient fluorescence, which shows a broad application prospect in fluorescent labeling, biological imaging, cell tracking and drug delivery.     

Unique CNTs-chained Li4Ti5O12 nanoparticles as excellent high rate anode materials for Li-ion capacitors

Composite anode materials with a unique architecture of carbon nanotubes (CNTs)-chained spinel lithium titanate (Li₄Ti₅O₁₂, LTO) nanoparticles are prepared for lithium ion capacitors (LICs). The CNTs networks derived from commercial conductive slurry not only bring out a steric hindrance effect to restrict the growth of Li₄Ti₅O₁₂ particles but greatly enhance the electronic conductivity of the CNTs/LTO composites, both have contributed to the excellent rate capability and cycle stability. The capacity retention at 30 C (1 C = 175 mA g^?1) is as high as 89.7% of that at 0.2 C with a CNTs content of 11 wt%. Meanwhile, there is not any capacity degradation after 500 cycles at 5 C. The LIC assembled with activated carbon (AC) cathode and such a CNTs/LTO composite anode displays excellent energy storage properties, including a high energy density of 35 Wh kg^?1 at 7434 W kg^?1, and a high capacity retention of 87.8% after 2200 cycles at 1 A g^?1. These electrochemical performances outperform the reported data achieved on other LTO anode-based LICs. Considering the facile and scalable preparation process proposed herein, the CNTs/LTO composites can be very potential anode materials for hybrid capacitors towards high power-energy outputs.     

Combating Biofilm Associated Infection In Vivo: Integration of Quorum Sensing Inhibition and Photodynamic Treatment based on Multidrug Delivered Hollow Carbon Nitride Sphere

Recently, quorum sensing (QS) inhibitors (QSIs) have been combined with antibiotics to enhance antibiofilm efficacy in vitro and in vivo. However, targeting QS signals alone is not enough to prevent bacterial infections. Drug resistance and recurrence of biofilms makes it difficult to eradicate. Herein, photodynamic therapy (PDT) is selected to unite QSIs and antibiotics. A synergistically antibiofilm system, which combines QSIs, antibiotics, and PDT based on hollow carbon nitride spheres (HCNSs) is envisaged. First, HCNS provides the multidrug delivering ability, enabling QSIs and antibiotics to be released in sequence. Subsequently, multistage releases sensitize bacteria effectively, potentiating the chemotherapeutic effects of the antibiotics. Finally, the integration of QSIs and PDT not only minimizes the possibility of drug resistance, but also overcomes the problem of limited mass and extension of PDT. Even after 48 h of incubation, the bacterial biofilm is obviously inhibited. And its biofilm disperse efficiency exceeds 48% (compared with QSI‐potentiated chemotherapy group) and 40% (compared with PDT group). Besides, the inhibition of the QS system influences phenotypes related to virulence factor production and surface hydrophobicity, which weaken biofilm invasion and formation. Eventually, this system is applied to disperse bacterial biofilm in vivo. Overall, PDT and QS modulation are devoted to eradicate drug resistance and recurrence of the biofilm.     

酸改性CoPd/TiO2催化CH4-CO2直接合成C2含氧化合物

采用酸处理方法对CoPd/TiO₂催化剂进行改性，并将酸改性催化剂用于温和条件下CH₄-CO₂梯阶转化直接合成C₂含氧化合物（乙酸和乙醇）的反应。在150～300℃考察了浸酸方式和不同种类酸处理对催化剂活性和选择性的影响。采用X射线衍射（XRD）、X射线光电子能谱（XPS）、NH₃程序升温脱附（NH₃-TPD）和N₂吸附对催化剂进行了表征。结果表明，酸改性明显提高了CoPd/TiO₂上C₂含氧化合物的生成速率和选择性。浸酸方式对催化剂性能和结构有显著影响，先用酸浸渍载体然后再浸渍活性金属所得催化剂具有更高的活性。在H₃PO₄、HNO₃和HCl中，H₃PO₄浸渍的催化剂活性最佳，在150℃时C₂含氧化合物（乙酸和乙醇）的生成速率为3365 μg/(g·h)，选择性达到91%。     

Efficient dye-sensitized solar cells based on CNTs and Zr-doped TiO2 nanoparticles

The light scattering, harvesting and adsorption effects in dye-sensitized solar cells (DSSCs) are studied by preparation of coated carbon nanotubes (CNTs) with TiO₂ and Zr-doped TiO₂ nanoparticles in the forms of mono- and double-layer cells. X-ray diffraction (XRD) analysis reveals that the phase composition of Zr-doped TiO₂ electrode is a mixture of anatase and rutile phases with major rutile content, whereas it is the same mixture with major anatase content for coated CNTs with TiO₂. Furthermore, the average crystallite size of Zr-doped TiO₂ electrode is slightly decreased with Zr introduction. Field emission scanning electron microscope (FE-SEM) images show that the porosity of Zr-doped TiO₂ electrodes is higher than that of undoped electrode, enhancing dye adsorption. UV–visible spectroscopy analysis reveals that the absorption onset of Zr-doped TiO₂ electrodes is slightly shifted to longer wavelength (the red-shift) in comparison with that of undoped TiO₂ electrode. Moreover, the band gap energy of TiO₂ nanoparticles is decreased by Zr introduction, enhancing light absorption. It is found that electron injection of monolayer TiO₂ electrode is improved by introduction of 0.025 mol% Zr, resulted in enhancement of its power conversion efficiency (PCE) up to 6.81% compared with 6.17% for pure TiO₂ electrode. Moreover, electron transport and light scattering are enhanced by incorporation of 0.025 wt% coated CNTs with TiO₂ in the over-layer of double layer electrode. Therefore, double layer solar cell composed of 0.025 mol% Zr-doped TiO₂ nanoparticles as the under-layer and mixtures of these nanoparticles and 0.025 wt% coated CNTs with TiO₂ as the over-layer shows the highest PCE of 8.19%.     

Two-step method to deposit ZrO2 coating on carbon fiber: Preparation,characterization, and performance in SiC composites

Recently, ceramic matrix composites reinforced by short carbon fibers (CFs) attracted increasing attentions. To further improve mechanical properties and oxidation resistances, CFs were subjected to oxidation and acidification followed by sol-gel dip-coating to deposit ZrO₂ on their surfaces. ZrO₂-C_f/SiC composites were fabricated by joint hot compression molding and sintering, compared to C_f/SiC and SiC prepared by the same method. Microstructural analyses indicated that ZrO₂ coatings were successfully deposited on CF surfaces, formed strong bonding and interfaces between CF and the matrix. Meanwhile, CFs were found uniformly distributed in SiC matrix with random orientations. Flexural curves of ZrO₂-C_f/SiC and C_f/SiC revealed the presence of “false plasticity” regions after sharp drops, which were quite different from brittle flexural behavior of SiC ceramic. Compression strength of the three samples showed step-up growth. ZrO₂-C_f/SiC exhibited the highest value, indicating the introduction of CFs and ZrO₂ coatings do have great influence on mechanical performances. After heat treatment, ZrO₂-C_f/SiC exhibited better oxidation resistance than C_f/SiC, with weight loss ratios estimated to ??3.76% and ??6.43%, respectively. These improved properties indicated that ZrO₂-C_f/SiC would be excellent alternatives to other existence materials under ultra-high temperature environments.     

Synergistic flame retardant effects of activated carbon and molybdenum oxide in poly(vinyl chloride)

The synergistic effects of activated carbon (AC) and molybdenum oxide (MoO₃) in improving the flame retardancy of poly(vinyl chloride) (PVC) were investigated. The effects of AC, MoO₃ and their mixture with a mass ratio of 1:1 on the flame retardancy and smoke suppression properties of PVC were studied using the limiting oxygen index and cone calorimeter tests. It was found that the flame retardancy of the relatively cheaper AC was slightly weaker than that of MoO₃. In addition, the incorporation of AC and MoO₃ greatly reduced the total heat release and improved smoke suppressant property of PVC composites. When the total content of AC and MoO₃ was 10 phr, PVC/AC/MoO₃ had the lowest peak heat release rate and peak smoke production rate values of 173.80 kW m^?2 and 0.1472 m² s^?1, which represented reductions of 47.3 and 59.9%, respectively, compared with those of PVC. Furthermore, thermogravimetric analysis and gel content tests were used to analyze the flame retardant mechanism of AC and MoO₃, with results showing that AC could promote early crosslinking in PVC. Char residue left after heating at 500 °C was analyzed using scanning electron microscopy and Raman spectroscopy, and the results showed that MoO₃ produced the most compact char, with the smallest and most organized carbonaceous microstructures. © 2017 Society of Chemical Industry