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•Al was modified by soaking Al powder in water and then heat-treating in vacuum.•Modified Al has a high rate in reduction of Cr(VI) to Cr(III) ions in solution.•Modified Al exhibited ...an excellent recyclability in removing Cr(VI).•XPS indicated that Al surface passive oxide films become thin after modification.
Zero-valent aluminum has attracted considerable attention in degradation of organic contaminants and reduction of heavy metal ions due to its very low redox potential (E0(Al3+/Al0) = −1.662 V). Usually there is a passive oxide film on Al surface, inhibiting its electron transfer and leading to low reaction efficiency. In this work, metal Al surface was modified by loose fine Al2O3 (SM-Al) using a procedure of soaking Al powder in water for a time period and then heat-treating in vacuum. It was found that surface modification remarkably enhanced the reaction efficiency of zero-valent Al in reduction of Cr(VI) to Cr(III) ions in aqueous solution. The longer the soaking time of Al powder in water is, the higher the efficiency in removing Cr(VI) is. The effects of Al particle size and dosage, initial Cr(VI) concentration and reaction temperature on Cr(VI) removal were investigated as well. XPS analyses revealed that the decrease in thickness of Al surface passive oxide films and the promotion of surface covered loose Al2O3 phases on hydration of passive oxide films are two main reasons responsible for the rapid removal of Cr(VI) by SM-Al. Meanwhile, SM-Al exhibited an excellent recyclability and the reused SM-Al has a very fast reaction rate relative to as-prepared SM-Al, 80% of Cr(VI) can be removed even it was reused up to five cycles. The present study provides a new route to activate Al in removal of contaminants in aqueous solution.
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•LDH-biopolymer interactions must be understood to design hybrid materials.•Biopolymer adsorption changes the surface charge and aggregation properties.•Colloidal stability of the ...composites must be tuned to avoid particle aggregation.•Biopolymers proved to stabilize delivery particle systems during medical uses.•Quantitative dispersion studies on LDH-biopolymer systems are still needed.
Layered double hydroxides (LDHs) are appealing nanomaterials for (bio)medical applications and their potential is threefold. One can gain advantage of the structure of LDH frame (i.e., layered morphology), anion exchanging property towards drugs with acidic character and tendency for facile surface modification with biopolymers. This review focuses on the third aspect, as it is necessary to evaluate the advantages of polymer adsorption on LDH surfaces. Beside the short discussion on fundamental and structural features of LDHs, LDH-biopolymer interactions will be classified in terms of the effect on the colloidal stability of the dispersions. Thereafter, an overview on the biocompatibility and biomedical applications of LDH-biopolymer composite materials will be given. Finally, the advances made in the field will be summarized and future research directions will be suggested.
Despite the favorable properties, ZSM-5 still suffers from deposition of coke in vital pores of catalyst (reversible deactivation) as well as dealumination (irreversible deactivation) due to ...operating conditions of MTP process. As for reversible deactivation, optimizing gel properties, nano-sizing the crystals using seed, moderating acidity by appropriate promoters and fabricating hierarchical structure, effectively inhibit coke deposition. Conversely, irreversible deactivation is controllable by incorporation of P to maintain Als under extreme hydrothermal condition and successive regenerations. The addition of Si is also an applicable route to passivate catalyst surface and prevent from water adsorption. Based on various operation conditions adopted in literature, this review compared effects of each strategy on propylene production and lifetime of catalysts. Investigations exhibited that a superior ZSM-5, contains acid sites with high accessibility and moderated acidity to inhibit coke related issues, while the presence of Si and P provide the hydrophobicity and protection of aluminums, respectively.
A superhydrophilic and underwater superoleophobic PVDF membrane (PVDFAH) has been prepared by surface-coating of a hydrogel onto the membrane surface, and its superior performance for oil/water ...emulsion separation has been demonstrated. The coated hydrogel was constructed by an interfacial polymerization based on the thiol-epoxy reaction of pentaerythritol tetrakis (3-mercaptopropionate) (PETMP) with diethylene glycol diglycidyl ether (PEGDGE) and simultaneously tethered on an alkaline-treated commercial PVDF membrane surface via the thio-ene reaction. The PVDFAH membranes can be fabricated in a few minutes under mild conditions and show superhydrophilic and underwater superoleophobic properties for a series of organic solvents. Energy dispersive X-ray (EDX) analysis shows that the hydrogel coating was efficient throughout the pore lumen. The membrane shows superior oil/water emulsion separation performance, including high water permeation, quantitative oil rejection, and robust antifouling performance in a series oil/water emulsions, including that prepared from crude oil. In addition, a 24 h Soxhlet-extraction experiment with ethanol/water solution (50:50, v/v) was conducted to test the tethered hydrogel stability. We see that the membrane maintained the water contact angle below 5°, indicating the covalent tethering stability. This technique shows great promise for scalable fabrication of membrane materials for handling practical oil emulsion purification.
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•Ultrafine Ag nanoparticles ejection phenomenon of micron Ag flake is observed for the first time by in-situ TEM.•In-situ surface modification of Al particles in sintered Ag-Al ...composite is completed via Ag nanoparticles ejection phenomenon.•A specific Ag/nano Ag2O/Al2O3 amorphous/Al composite interface structure was formed via mutual dissolution at the atomic level.•Shear strength of sintered Ag-10Al joint reached 34.1 MPa after 1000 h aging, meeting the requirements for power semiconductor packaging.
The increasing demand for high-power SiC semiconductors necessitate the development of a die attachment material that combines high-temperature resistance, reliability, and cost-effectiveness. In this study, a novel micro-sized composite, Ag-10Al paste, containing 10 wt% Al particles, was designed. A remarkable phenomenon, the ejection of ultrafine Ag nanoparticles from micron-sized Ag flakes, was observed for the first time. The phenomenon was utilized for the in-situ surface modification of Al. Subsequently, the microstructure and mechanical properties of the sintered Ag-10Al/direct bonded copper (DBC) joints were studied. Results indicated that the Ag-10Al composite exhibited superior microstructure stability compared to sintered Ag. The Ag/Al interface was systematically analyzed, revealing a unique Ag/nano Ag2O/Al2O3 amorphous/Al structure. This structure was formed through the Ag nanoparticle jetting effect of Ag flakes, achieving effective bonding between nano Ag2O and Al2O3 amorphous phases through mutual dissolution at the atomic level. Moreover, the sintered Ag-10Al joint demonstrated enhanced mechanical performance stability over the sintered Ag joint. After 1000 h aging at 300 ℃, the shear strength of the sintered Ag-10Al joint reached 34.1 MPa, meeting the requirements for power semiconductor packaging. In conclusion, the Ag-10Al composite paste was thoughtfully designed, excelling in both performance and cost-effectiveness.
An enormous amount of research had been dedicated to exploring the nanotechnology over the past decade. The fast-paced development of nanomaterial production has enhanced the application of zinc ...oxide (ZnO) in a wide variety fields. ZnO nanoparticles can be obtained mechanically or chemically for commercial use. However, the environmental issues raised by these techniques have been brought to the world’s attention. Nowadays, green synthesis of ZnO nanoparticles is of particular interest in the research field aiming to mitigate environmental problems. In this green approach, natural based materials such as plant extract, microbes, fungus and algae are used as bio-reductants and bio-stabilizers due to their enrichment in bioactive phytochemicals. Numerous studies have proven that the green synthesis is facile and feasible to produce ZnO nanopowder with advanced properties as compared to the chemically synthesized ZnO nanoparticles. In order to make the green synthesized ZnO nanoparticles more applicable in a wide range of uses, surface modification using metal and non-metal ions are applied to alter and improve the properties of ZnO nanoparticles. The findings available currently represent an excellent initial step towards the promising green approach in the synthesis of ZnO nanoparticles and additional work should be undertaken to exploit the application of green synthesis in the commercial platform.
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•Various synthesized pathways of zinc oxide for environmental application are reviewed.•Progress on the green synthesized zinc oxide using natural-based materials is summarized.•Recent works on various surface modifications and applications of green synthesized zinc oxide are discussed.•Mechanism and future prospects of green synthesized zinc oxide are highlighted.
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•The selective layer of carboxymethyl cellulose was formed on the PES support.•The Dip-coating technique was used to fabricate thin-film composite membranes.•The negatively charged NF ...membranes exhibited great desalination performance.•The flux recovery ratio of CMC/PES NF membranes was achieved up to 75%.
Herein, we report the fabrication of carboxymethyl cellulose (CMC)/polyethersulfone (PES) thin-film composite nanofiltration membranes using a dip-coating method with glutaraldehyde (GA) as the crosslinking agent. The effects of crosslinking degree and the dip-coating parameters, including CMC concentration and dipping time, on the performance and morphology of the fabricated membranes were investigated. The properties of the prepared membranes were analyzed by ATR-FTIR, AFM, FE-SEM, and water contact angle analysis. The optimized membrane containing 0.2 wt% CMC, crosslinking degree of 20% by the dipping time of 10 min represented a rejection efficiency of 91.90%, 68.63%, and 45.90% towards the Na2SO4, MgSO4, and NaCl solutions (100 mg/L), respectively. The pure water flux of the optimal membrane was 47.90 ± 1.77 L/m2 h under a low transmembrane pressure of 0.4 MPa. The flux recovery ratio of the nanofiltration membrane was 63% higher than the PES support membrane, indicating an improvement in fouling resistance.
As one of the most promising cathode materials for next-generation of lithium-ion batteries, Li-rich Mn-based oxides are still hindered by inferior cycling properties and poor rate performance. ...Surface modification is proved to be feasible to tackle these problems. Herein, we chose phytic acid to construct spinel and Li3PO4 double protection layers on the Li1.2(Ni0.17Co0.07Mn0.56)O2 cathode material via a simple synchronous approach. The 3 wt% phytic acid treated sample achieves markedly enhanced electrochemical performance, such as elevated initial Coulombic efficiency reaching 90.0%, increased capacity retention of 87.8% after 150 cycles at 1 C and alleviated average discharge voltage drop of 1.63 mV per cycle. These impressive electrochemical properties can be ascribed to the designed hierarchical interface, which not only can synergistically retain structural stability but also provide fast Li+ transport channels. Taken together, this work employs a facile and novel route to enhance the electrochemical performance of Li1.2(Ni0.17Co0.07Mn0.56)O2, which may afford inspiration to the commercialization of Li-rich cathode materials.
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2,2,6,6-Tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation is a unique reaction to native and regenerated celluloses, and has advantages in terms of position-selective ...reaction at room temperature under aqueous conditions. When the TEMPO/NaBr/NaClO oxidation is applied to native celluloses in water at pH 10 under suitable conditions, the C6-primary hydroxy groups present on crystalline cellulose microfibril surfaces are mostly converted to sodium C6-carboxylate groups. Anionic sodium glucuronosyl units are densely, regularly, and position-selectively formed on crystalline cellulose microfibril surfaces, while maintaining the original cellulose morphology, cellulose I crystal structure, crystallinity, and crystal width. When TEMPO-oxidized celluloses (TOCs) prepared from, for example, wood cellulose have sodium C6-carboxylate contents >1 mmol/g, transparent highly viscous gels consisting of TEMPO-oxidized cellulose nanofibrils (TOCNs) with homogeneous widths of ≈3 nm and lengths >0.5 μm, dispersed at the individual nanofiber level, are obtained by gentle mechanical disintegration of TOCs in water. Alternative systems are as follows: TEMPO/NaClO/NaClO2 system, TEMPO electro-mediated oxidation, etc. TOCNs are promising new plant-based renewable nanofibers applicable to high-tech material fields.
Chemotherapy resistance remains a major hurdle for cancer therapy in clinic because of the poor cellular uptake and insufficient intracellular release of drugs. Herein, an intelligent, ...multifunctional MoS2 nanotheranostic (MoS2-PEI-HA) ingeniously decorated with biodegradable hyaluronic acid (HA) assisted by polyethyleneimine (PEI) is reported to combat drug-resistant breast cancer (MCF-7-ADR) after loading with the chemotherapy drug doxorubicin (DOX). HA can not only target CD44-overexpressing MCF-7-ADR but also be degraded by hyaluronidase (HAase) that is concentrated in the tumor microenvironment, thus accelerating DOX release. Furthermore, MoS2 with strong near-infrared (NIR) photothermal conversion ability can also promote the release of DOX in the acidic tumor environment at a mild 808 nm laser irradiation, achieving a superior antitumor activity based on the programmed response to HAase and NIR laser actuator. Most importantly, HA targeting combined with mild NIR laser stimuli, rather than using hyperthermia, can potently downregulate the expression of drug-resistance-related P-glycoprotein (P-gp), resulting in greatly enhanced intracellular drug accumulation, thus achieving drug resistance reversal. After labeled with 64Cu by a simple chelation strategy, MoS2 was employed for real-time positron emission tomography (PET) imaging of MCF-7-ADR tumor in vivo. This multifunctional nanoplatform paves a new avenue for PET imaging-guided spatial–temporal-controlled accurate therapy of drug-resistant cancer.
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