Two‐dimensional (2D) graphitic carbon nitride (g‐C3N4) nanosheets show brilliant application potential in numerous fields. Herein, a membrane with artificial nanopores and self‐supporting spacers was ...fabricated by assembly of 2D g‐C3N4 nanosheets in a stack with elaborate structures. In water purification the g‐C3N4 membrane shows a better separation performance than commercial membranes. The g‐C3N4 membrane has a water permeance of 29 L m−2 h−1 bar−1 and a rejection rate of 87 % for 3 nm molecules with a membrane thickness of 160 nm. The artificial nanopores in the g‐C3N4 nanosheets and the spacers between the partially exfoliated g‐C3N4 nanosheets provide nanochannels for water transport while bigger molecules are retained. The self‐supported nanochannels in the g‐C3N4 membrane are very stable and rigid enough to resist environmental challenges, such as changes to pH and pressure conditions. Permeation experiments and molecular dynamics simulations indicate that a novel nanofluidics phenomenon takes place, whereby water transport through the g‐C3N4 nanosheet membrane occurs with ultralow friction. The findings provide new understanding of fluidics in nanochannels and illuminate a fabrication method by which rigid nanochannels may be obtained for applications in complex or harsh environments.
A g‐C3N4 membrane assembled from two‐dimensional g‐C3N4 nanosheets demonstrates good chemical and mechanical stability, as well as ultralow water friction when applied in water purification. The nanosheets contain intrinsic (P1) and artificial (P2) nanopores, as well as self‐supporting spacers (S) formed by adhered unstripped fragments.
The epoxy composite cured by imidazole has better heat resistance. In this paper, the heat-driven mass loss process of epoxy resin matrix and carbon fiber epoxy laminate cured by 2E4MI, a kind of ...imidazole, were investigated by thermogravimetric analysis at different heating rates under nitrogen and air atmosphere. It was observed that the pyrolysis reactions of epoxy resin cured with imidazole and its carbon fiber epoxy laminate consist of one step in the nitrogen atmosphere, but in air atmosphere, their pyrolysis reactions consist of three and four steps, respectively. The glass transition temperature of 2E4MI cured epoxy resin was obtained around 143–150 °C and the variation of specific heat capacity with temperature was obtained between 20 and 230 °C. Furthermore, kinetic parameters for the pyrolysis of the samples were estimated using Kissinger and FWO method. The apparent activation energy and the apparent pre-exponential factor of 2E4MI cured epoxy resin were obtained around 165 kJ mol
−1
and 4.85 × 10
8
in nitrogen, and these values in air were less. To carbon fiber epoxy laminate, these values were around 166 kJ mol
−1
and 6.68 × 10
8
in nitrogen. It was shown that the thermal performance of the 2E4MI cured epoxy resin determined the thermal performance of the carbon fiber laminate to a large extent. So, the use of curing agent in epoxy resin indirectly determines the thermal properties of composites.
As nano-scale biological vesicles, extracellular vesicles (EVs)/exosomes, in particular, exosomes derived from mesenchymal stem cells (MSC-exosomes), have been studied in the diagnosis, prevention, ...and treatment of many diseases. In addition, through the combination of nanotechnology and biotechnology, exosomes have emerged as innovative tools for the development of nanomedicine. This review focuses on a profound summarization of MSC-exosomes as a powerful tool in bionanomedicine. It systemically summarizes the role of MSC-exosomes as a nanocarrier, drug loading and tissue engineering, and their potential contribution in a series of diseases as well as the advantages of exosomes over stem cells and synthetic nanoparticles and potential disadvantages. The in-depth understanding of the functions and mechanisms of exosomes provides insights into the basic research and clinical transformation in the field of nanomedicine.
A gentle method is used to treat the precursor to induce the doping of SO4 2– and Ni2+. The doped SO4 2– induces the formation of oxygen vacancies and defects, which are beneficial for inhibition of ...the loss of O2–, stabilization of the structure, and amelioration of voltage decay, and the doped Ni2+ increases the degree of lithium nickel mixing and significantly increases the midvoltage. After modification, the specific discharge capacity reaches 305.20 mAh g–1, with a Coulombic efficiency of 86.20% (the specific discharge capacity and Coulombic efficiency of the original material are only 276.50 mAh g–1 and 77.30%, respectively). In addition, the cycle performance is also significantly improved, and the discharge midvoltage is dramatically increased from 2.74 to 3.00 V after 350 cycles at a large current density of 1C due to the dual-ion synergistic effect. In summary, these results show that the materials exhibit not only a more stable structure but also better electrochemical performance after modification.
Municipal solid waste incineration fly ash (MSWIFA), as a hazardous solid waste, contains such toxic substances as heavy metals and dioxin, making its disposal a global public health concern. This ...study aims to comprehensively combine solid waste red mud (RM), carbide slag (CS), and MSWIFA into eco-friendly geopolymer. This experiment used CS slurry and RM slurry without drying and grinding, effectively reducing energy consumption and cost. The mechanical and environmental properties of geopolymer were characterized by strength, chloride ion curing rate, and leaching concentration of heavy metals. The microscopic hydration mechanism of the binder was investigated using XRD, FTIR, TG-DTG, SEM + EDS, and MIP tests. The results show that when RM: CS: MSWIFA = 5: 2: 3, the 28 d compressive strength can reach 11.7 MPa, the chloride ion curing rate is 80.41%, and leaching levels of toxic substances are lower than the limits for landfill disposal regulated by the China standard (GB16889-2008). The Al–O and Si–O chemical bonds in RM were broken in the alkaline environment provided by CS and MSWIFA, and formed hydrate calcium chloroaluminate (HCC) and C–S–H gel with calcium ions and chloride ions. These hydration products can fill pores and reduce porosity, making the pores in the structure mainly gel micropores and mesopores with volume fractions of 10.3 and 68.1% respectively. This study expands the application of a new waste alkaline activator in alkaline activation and provides methods for MSWIFA solidification.
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•The synergistic use of CS and MSWIFA as alkaline activators outperformed single mixing.•The highest compressive strength was obtained with a RM-to–CS–to-MSWIFA ratio of 5:2:3.•C–S–H gel and HCC are the main hydration products, enhancing the pore structure.•The new geopolymer has good ability to immobilize heavy metals and chloride ions.
MOF membranes are very promising in molecular separation, but it is still a challenge for industrial applications due to the complex and time‐consuming synthesis. We use the fast current‐driven ...synthesis (FCDS) method to achieve controlled growth of ZIF‐8 membranes on porous graphite‐coated ceramic tubes by controlling the growth time and current density. Grown for 30 min at a current density of 0.74 mA/cm2, the ZIF‐8 membrane exhibits selectivity for C3H6/C3H8 up to 63 with C3H6 permeance of 6 × 10−9 mol/(m2 s Pa). Furthermore, the ZIF‐8 membrane exhibits a pressure resistance of up to 3 bar and good stability of ~96 h. This work realizes the breakthrough of the MOF membrane synthesis via FCDS method from the frequently‐used expensive and fragile anodic aluminum oxide (AAO) disc substrate to the tough ceramic tubular substrate, which broadens the road for the industrialization of MOF membranes in gas separation fields.
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Iron-based metal–organic frameworks (MOFs) with low cost and excellent photocatalytic potential are extremely attractive in the field of energy utilization and environmental ...remediation. In this study, a novel In2S3/MIL-100(Fe) photocatalyst was successfully synthesized by a facile solvothermal method for the first time. Several technologies (such as X-ray diffraction, scanning electron microscope, transmission electron microscope, and X-ray photoelectron spectroscopy) were used to characterize the as-obtained samples and demonstrate the successful combination of MIL-100(Fe) and In2S3. Experimental results showed that 18% of tetracycline (TC) was adsorbed under dark condition and another 70% of TC was degraded under visible-light irradiation when treating 100 mL of TC solution (10 mg/L) with 30 mg of In2S3/MIL-100(Fe) composites. The corresponding TC removal efficiency was almost 1.9 and 1.6 times higher than that of pure MIL-100(Fe) and In2S3, respectively. The mechanism investigations revealed that the heterojunction composite exhibited superior charge transfer than either MIL-100(Fe) or In2S3, and this caused more efficient separation of electron-hole pairs. As a result, more radicals and holes were generated in the composite, leading to better photocatalytic performance. This work highlights the powerful combination of MOFs and semiconductor, which is a promising approach to fabricate heterojunction photocatalyst for wastewater purification.
With the increasing energy demand together with the deteriorating environment and decreasing fossil fuel resources, the development of highly efficient energy conversion and storage devices is one of ...the key challenges of both fundamental and applied research in energy technology. Melamine sponges (MS) with low density, high nitrogen content, and high porosity have been used to design and obtain three‐dimensional porous carbon electrode materials. More importantly, they are inexpensive, environment‐friendly, and easy to synthesize. There have been many reports on the modification of carbonized MS and MS‐based composites for supercapacitor and lithium battery electrode materials. In this paper, recent studies on the fabrication of electrode materials using MS as raw materials have been mainly reviewed, including carbonation, doping activation, and composite modification of MS, and expectations for the development of porous carbon materials for energy storage as a reference with excellent performance, environment‐friendliness, and long life.
Melamine sponges (MS) with high nitrogen content and porosity have been used to design three‐dimensional porous carbon electrode materials. There have been many reports on the modification of carbonized MS and MS‐based composites for supercapacitor and lithium battery electrodes materials. This paper reviewed the recent studies on the fabrication of electrode materials by using MS as raw materials, including carbonation, doping activation, and composite modification.
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