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Membrane separation has enjoyed tremendous advances in relevant material and engineering sciences, making it the fastest growing technology in water treatment. Although membranes as a ...broad-spectrum physical barrier have great advantages over conventional treatment processes in a myriad of applications, the need for higher selectivity and specificity in membrane separation is rising as we move to target contaminants at trace concentrations and to recover valuable chemicals from wastewater with low energy consumption. In this review, we discuss the drivers, fundamental science, and potential enabling materials for high selectivity membranes, as well as their applications in different water treatment processes. Membrane materials and processes that show promise to achieve high selectivity for water, ions, and small molecules—as well as the mechanisms involved—are highlighted. We further identify practical needs, knowledge gaps, and technological barriers in both material development and process design for high selectivity membrane processes. Finally, we discuss research priorities in the context of existing and future water supply paradigms.
In recent years, with the higher requirements for the performance of cement-based materials and the call for energy conservation and environmental protection, a wave of research on new materials has ...set off, and various high-performance concrete and more environmentally friendly geopolymers have appeared in the public. With a view to solving the defects of energy consumption, environmental protection and low toughness of traditional cement-based materials. At the same time, nanomaterials have become a focus of current research. Therefore, the research on the properties of cement-based materials and geopolymers modified by graphene and its derivatives has aroused extensive interest of researchers. Graphene-based nanomaterials are one of them. Because of their large specific surface area, excellent physical properties have been favored by many researchers. This paper reviews the research progress of graphene-based nanomaterials in improving the properties of cement-based materials and geopolymer materials, and points out the main challenges and development prospects of such materials in the construction field in the future.
Sepsis-associated encephalopathy (SAE) is a serious complication of sepsis. The tumour necrosis factor receptor superfamily member 6 (TNFRSF6) gene encodes the Fas protein, and it participates in ...apoptosis induced in different cell types. This study aimed to explore TNFRSF6 function in SAE. The SAE mouse model was established by intraperitoneal injection of LPS in TNFRSF6-/- mice and C57BL/6J mice. Microglia were treated with LPS to establish the cell model. The learning, memory and cognitive functions in mice were tested by behavioral tests. Nissl staining was utilized for determining neuronal injury. Microglial activation was tested by immunofluorescence assay. ELISA was utilized for determining TNF-α, IL-1β, IL-6, and IL-10 contents. Mitochondrial dysfunction was measured by mitochondrial oxygen consumption, ATP content, ROS production, and JC-1 assay. TNFRSF6 was upregulated in the LPS-induced mouse model and cell model. TNFRSF6 deficiency notably alleviated the impaired learning, memory and cognitive functions in SAE mice. Furthermore, we found that TNFRSF6 deficiency could alleviate neuronal injury, microglial activation, and inflammation in SAE mice. Additionally, mitochondrial dysfunction in the SAE mice was improved by TNFRSF6 depletion. In the LPS-induced microglia, we also proved that TNFRSF6 knockdown reduced inflammatory response inhibited ROS production, and alleviated mitochondrial dysfunction. TNFRSF6 induced mitochondrial dysfunction and microglia activation in the in vivo and in vitro models of SAE.
Abstract
Formation of mineral scale on a material surface has profound impact on a wide range of natural processes as well as industrial applications. However, how specific material surface ...characteristics affect the mineral-surface interactions and subsequent mineral scale formation is not well understood. Here we report the superior resistance of hexagonal boron nitride (
h
BN) to mineral scale formation compared to not only common metal and polymer surfaces but also the highly scaling-resistant graphene, making
h
BN possibly the most scaling resistant material reported to date. Experimental and simulation results reveal that this ultrahigh scaling-resistance is attributed to the combination of
h
BN’s atomically-smooth surface, in-plane atomic energy corrugation due to the polar boron-nitrogen bond, and the close match between its interatomic spacing and the size of water molecules. The latter two properties lead to strong polar interactions with water and hence the formation of a dense hydration layer, which strongly hinders the approach of mineral ions and crystals, decreasing both surface heterogeneous nucleation and crystal attachment.
One antibacterial material was prepared from exfoliated graphite (EG) decorated with silver nanoparticles (AgNPs). The EG was prepared by the graphite intercalated compound process, AgNPs were ...prepared by chemical reduction of AgNO3 in the presence of NaBH4. The AgNPs-loaded EG (Ag-EG) composite was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), nitrogen adsorption, mercury intrusion porosimetry, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The antibacterial effect of the Ag-EG was evaluated by using the zone of inhibition method. The loaded AgNPs were highly dispersed on EG sheets and most of them have a size less than 10 nm. The Ag loading slightly increased the surface area of EG. It is shown that the Ag-EG had antibacterial activity and anti-adhesion properties against Pseudomonas aeruginosa and Staphylococcus aureus. It suggests that Ag-EG composites could be used in a variety of industrial applications that require an antibacterial effect.
Using a bi-polymer system comprising of transparent poly(methyl methacrylate) (PMMA) and poly(vinyl pyrrolidone) (PVP), a visible light active Ag3PO4/P25 composite was immobilized into the mats of ...polymeric electrospun nanofibers. After nanofibers synthesis, sacrificial PVP was removed, leaving behind rough surface nanofibers with easy access to Ag3PO4/P25 composite. The remarkable photocatalytic efficiency was attained using a PMMA and Ag3PO4/P25 weight ratio of 1:0.6. Methyl orange (MO) was used to visualize pollutant removal and exhibited stable removal kinetics up to five consecutive cycles under simulated daylight. Also, these polymeric nanofibers (NFs) revealed an important role in the destruction of microorganisms (E. coli), signifying their potential in water purification. A thin film fibrous mat was also used in a small bench scale plug flow reactor (PFR) for polishing of synthetic secondary effluent and the effects of inorganic salts were studied upon photocatalytic degradation in terms of total organic carbon (TOC) and turbidity removal. Lower flow rate (5 mL/h) resulted in maximum TOC and turbidity removal rates of 86% and 50%, respectively. Accordingly, effective Ag3PO4/P25 immobilization into an ideal support material and selectivity towards target pollutants could both enhance the efficiency of photocatalytic process under solar radiations without massive energy input.
Scale formation is an important challenge in water and wastewater treatment systems. However, due to the complex nature of membrane surfaces, the effects of specific membrane surface characteristics ...on scale formation are poorly understood. In this study, the independent effect of surface hydrophobicity on gypsum (CaSO4·2H2O) scale formation via surface-induced nucleation and bulk homogeneous nucleation was investigated using quartz crystal microbalance with dissipation (QCM-D) on self-assembled monolayers (SAMs) terminated with −OH, −CH3, and −CF3 functional groups. Results show that higher surface hydrophobicity enhances both surface-induced nucleation of gypsum and attachment of gypsum crystals formed from homogeneous nucleation in the bulk solution. The enhanced surface-induced nucleation is attributed to the lower nucleation energy barrier on a hydrophobic surface, while the increased gypsum crystal attachment results from the favorable hydrophobic interactions between gypsum and more hydrophobic surfaces. Contrary to previous findings, the role of Ca2+ adsorption in surface-induced nucleation was found to be relatively small and similar on the different SAMs. Therefore, increasing material hydrophilicity is a potential approach to reduce gypsum scaling.
Inorganic scaling caused by precipitation of sparingly soluble salts at supersaturation is a common but critical issue, limiting the efficiency of membrane-based desalination and brine management ...technologies as well as other engineered systems. A wide range of minerals including calcium carbonate, calcium sulfate, and silica precipitate during membrane-based desalination, limiting water recovery and reducing process efficiency. The economic impact of scaling on desalination processes requires understanding of its sources, causes, effects, and control methods. In this Critical Review, we first describe nucleation mechanisms and crystal growth theories, which are fundamental to understanding inorganic scale formation during membrane desalination. We, then, discuss the key mechanisms and factors that govern membrane scaling, including membrane properties, such as surface roughness, charge, and functionality, as well as feedwater characteristics, such as pH, temperature, and ionic strength. We follow with a critical review of current characterization techniques for both homogeneous and heterogeneous nucleation, focusing on the strengths and limitations of each technique to elucidate scale-inducing mechanisms, observe actual crystal growth, and analyze the outcome of scaling behaviors of desalination membranes. We conclude with an outlook on research needs and future research directions to provide guidelines for scale mitigation in water treatment and desalination.
Metal-organic frameworks (MOFs) are emerging nanomaterials with widespread applications for their superior properties. However, the potential health and environmental risks of MOFs still need further ...understanding. In this work, we investigated the toxicity of a typical cobalt-based MOF (ZIF-67) with varied primary particle sizes (100, 200, 400, 700 and 1200 nm) to Photobacterium Phosphoreum T3 strain, a kind of luminescent bacteria. The luminescence inhibition rate of all ZIF-67 nanoparticles (NPs) reached 40 % and higher at the concentration of 5 mg/L, exhibiting strong toxicity. Combined cellular assays and gene expression analysis confirmed that the general bioactivity inhibition and oxidative damage were induced mainly by ZIF-67 NPs, rather than Co2+ released from the ZIF-67 NPs. Additionally, the toxicity of ZIF-67 NPs demonstrated an evident size-dependent effect. For ZIF-67 smaller than 400 nm, the toxicity increased with the particle size decreased, while the trend was not significant when the particle size was larger than 400 nm. A potential explanation for this phenomenon is the smaller NPs (100 and 200 nm) may enter the cytoplasm, accumulating in the cytoplasm and causing more severe toxicity. Furthermore, Co2+ released from the ZIF-67 NPs was not the primary contributor to the toxic effect of ZIF-67 NPs which was verified by the toxicity results and the variation of toxicity-related indicators. These findings provided insight into the better design and safer use of MOFs, and it also implied the potential environmental risk of the MOF's cannot be ignored, especially for the bioapplication.
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•Particle size-dependent toxicity of cobalt-based MOF was observed for Photobacterium phosphoreum T3 strain.•The difference in toxicity of the larger ZIF-67 NPs (>400 nm) was not significant.•Smaller ZIF-67 NPs (<400 nm) are more likely to cause the general bioactivity inhibition and oxidative damage.•Co2+ released from the ZIF-67 NPs not the sole contributor to the toxic effect of ZIF-67 NPs.
•The dispersion of graphene oxide under different ultrasonic power and ultrasonic time was studied.•The effect of GO on the fluidity of mortar was studied.•The reason why GO can improve the ...mechanical properties and durability of mortar was explained.
Graphene oxide (GO) is one of the nanomaterials that have attracted the most attention of researchers in recent years. Because of its excellent mechanical, thermal and electrical properties, it is widely used in the fields of energy, photoelectric, catalysis and materials, and it has shown broad development prospects. For the high demand of cement-based materials in buildings, as a new cement composites reinforcement agent, GO has been widely studied by researchers. Based on previous studies, cement, silica fume (SF) and fly ash (FA) were used as composite cementitious materials in this experiment, and the effects of different GO contents (0.00%, 0.01%, 0.03%, 0.05%, 0.07%) on the mechanical properties of mortar were analyzed. In addition, the impermeability and sulfate resistance of the modified mortar were studied. The results showed that under the same curing conditions and ages, when the GO content is 0.05%, the flexural strength of the specimens after 28 days of curing is the highest, reaching 10.8 MPa, and the improvement rate is 16.1%. When the GO content is 0.03%, the compressive strength of the specimens after 28 days of curing is the highest, reaching 64.5 MPa, and the improvement rate is 12.4%. In addition, when the dosage of GO is 0.03%, the durability of the mortar is also extremely improved. The impermeability of the mortar is 80% higher than the reference specimens. The strength retention rate under the action of sulfate corrosion is also the highest, which is 11.3% and 6.7% higher than the compressive strength and flexural strength of the reference specimens that corroded for 3 months. GO was proved to be an excellent reinforcement agent for cement-based materials. Through SEM and XRD analysis, it was found that GO promoted the hydration reaction, and it played a filling effect and template role in the mortar matrix. Its two-dimensional lamella structure regulates the morphology of hydration products and enhances the interface adhesion between the matrix and the aggregate. In addition, its nano-filling effect eliminates a large number of micro-pores in the mortar and increases the density of the matrix.
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