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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.
The aim of the present investigation was to study the anti-oxidant effect of chitosan nanoparticles on a human SH-SY5Y neuroblastoma cell line using a rotenone model to generate reactive oxygen ...species. Chitosan nanoparticles were synthesized using an ionotropic gelation method. The obtained nanoparticles were characterized using various analytical techniques such as Dynamic Light Scattering, Scanning Electron Microscopy, Transmission Electron Microscopy, Fourier Transmission Infrared spectroscopy and Atomic Force Microscopy. Incubation of SH-SY5Y cells with 50 µM rotenone resulted in 35-50% cell death within 24 h of incubation time. Annexin V/Propidium iodide dual staining verified that the majority of neuronal cell death occurred via the apoptotic pathway. The incubation of cells with chitosan nanoparticles reduced rotenone-initiated cytotoxicity and apoptotic cell death. Given that rotenone insult to cells causes oxidative stress, our results suggest that Chitosan nanoparticles have antioxidant and anti-apoptotic properties. Chitosan can not only serve as a novel therapeutic drug in the near future but also as a carrier for combo-therapy.
Poly(ether sulfone) (PES) is commonly used polymer in ultrafiltration (UF) membranes which, due to its hydrophobic nature, frequently incorporates the copolymer, polyvinylpyrrolidone (PVP), to ...improve its hydrophilicity. Membranes are periodically disinfected using bleach which chemically degrades PVP, thus removing its hydrophilic advantage. The utility of graphene oxide (GO) is compared with PVP as a hydrophilic and chemically stable additive in PES UF membranes. The performances of the membranes were evaluated by comparing pure water flux, contact angle, and fluxes during fouling tests before and after hypochlorite chemical washing after fouling (CWAF). Membranes containing low concentrations (<0.05% wt) of GO had an increase in rejection, lower porosity on average leading to less severe fouling, a higher sustainable flux, and greatly improved reversible fouling especially after CWAF tests compared with membranes containing PVP (1% wt). This research indicates that low concentrations of GO to PES can greatly improve the fouling of PES UF membranes while retaining a hydrophilic properties and provide improved chemical stability after hypochlorite exposure.
Electro-driven separation processes offer several potential advantages over pressure-driven separation processes such as reverse osmosis for water reuse and desalination, including energy savings for ...low-salinity waters, cation or anion selectivity, and versatility for fit-for-purpose treatment. In this perspective, we review technologies for electro-driven separation processes and evaluate their prospect for marginalized water sources and fit-for-purpose water treatment, which include improving freshwater sustainability, protecting environmental flows, and improving recycling of industrial process streams and municipal wastewater reuse. We discuss critical aspects related to application, implementation, and techno-economic evaluation of electro-driven separation technologies. Electro-driven processes provide viable options to enhance a circular water economy by reducing salinity and selectively separating contaminants while recovering valuable products with increased environmental sustainability.
•Tandem electro-driven separation processes are ideal for tailored desalination.•Selective membranes offer energy-efficient ion removal or recovery opportunities.•Electro-driven processes for brine management enable more sustainable desalination.
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•GO synthesized from different size precursor graphite using different oxidation methods.•Each GO shows distinct TGA, FTIR, and XRD characteristics.•Electrical conductivity correlates ...with GO flake size estimated by XRD technique.•Precursor size had no influence on rGO derived from extensively oxidized GO.
Exfoliation method is a most cost effective method for producing chemically derived-graphene (CDG) yet electronic performance of CDG strongly depends on the lateral and vertical dimensions of graphene especially in regards to the development of macroscopic scale films. This work demonstrates the variation in functionality of Graphene oxide (GO) prepared via Marcano-Tour’s and modified Hummer’s method using two different sized graphite precursors. Reduced GO papers were fabricated using vacuum filtration and examined by Hall probe and Raman spectroscopy to ensure their quality. A correlation between oxidation-controlled GO size with their overall electrical conductivity is explored by Fourier Transform Infrared spectroscopy (FTIR), Thermo Gravimetric Analysis (TGA) and X-ray Diffraction (XRD) techniques. This study reveals that the modified Hummer’s method suitably preserves basal planes of GO produced from larger GO flakes with less inter-sheet resistance and illustrates the importance of comparing synthetic methods for producing large area high quality graphene related nanostructures.
Herein, we present an experimental/computational approach for probing the interaction between metal contacts and carbon nanotubes (CNTs) with regard to creating the most efficient, low resistance ...junction. Tungsten probes have been coated with copper or chromium and the efficiency of nanocontact transport into multiwalled carbon nanotubes (MWCNTs) has been investigated experimentally, using scanning tunneling spectroscopy and nanoscale two-point probe I-V measurements, and in silico, employing DFT calculations. Experimental I-V measurements suggest the relative conductivity of the metal-CNT interaction to be Cu > W > Cr. It has been found that copper when in contact with MWCNTs results in a high density of states at the Fermi level, which contributes states to the conduction band. It was observed that the density of states also increased when chromium and tungsten probes were in contact with CNTs; however, in these cases the density of states increase would only occur under high voltage/high temperature situations. This is demonstrated by an increase in the experimental electrical resistance when compared to the copper probe. These results suggest that in future copper tips should be used when carrying out all intrinsic conduction measurements on CNTs, and they also provide a rationale for the ultraconductivity of Cu-CNT and Cu-graphene composites.
Asphaltenes are the molecular components of Asphalts and have polyaromatic hydrocarbon (PAH) structures similar to nanographenes. Thus, organic-based dye sensitized solar cells can be produced from ...asphaltenes. In addition, graphene based structures doped with transition metals can be synthesized from asphaltenes. These materials are simple to synthesize and inexpensive relative to other methods for doping graphene. Thus, what is considered a “Waste Material - Tar” can now be utilized in several important applications. These novel materials from asphaltene are also termed Discotic Liquid Crystals (DLC) and now have great potential in many areas, because of novel and valuable properties, easy synthesis and low cost.
Stair falls are common among young children and are also common false histories in cases of child abuse. When a child presents with a femur fracture and a stair-fall history, a judgment of ...plausibility must be made. A lack of objective injury and biomechanical data makes plausibility determination more difficult. Our objective was to characterize key features associated with femur fractures from reported stair falls, to develop a model for assessing injury plausibility (IP).
Children 2 to 36 months of age who presented with a femur fracture from a reported stair fall were studied prospectively. Detailed history recording, examinations, fracture characterization, and injury scene analyses were conducted, and biomechanical measures associated with injury prediction were calculated. With our proposed IP model, all cases were then scored for the detail of history, biomechanical compatibility of fracture morphologic features, time to seeking care, and presence of other injuries.
Twenty-nine children were diagnosed with a femur fracture resulting from a reported stair fall. The IP model made a clear distinction between 2 groups, designated plausible and suspicious. Significant differences were observed for the detail of history, biomechanical compatibility of fracture, time to seeking care, presence of other injuries, and total IP scores. In the plausible group, the minimal linear momentum associated with a transverse fracture was almost 10-fold greater than that for spiral or buckle fracture types.
This study adds new information to the current body of knowledge regarding injury biomechanics and fractures among children. The IP model provides an objective means of assessing plausibility of reported stair-fall-related femur fractures and identifies key characteristics to facilitate decision-making.
Objective: The objectives of our study were to assess biomechanics associated with feet-first free falls in 3-year-old children and to investigate the influence of impact surface type and fall height ...on key biomechanical measures associated with injury risk.
Methods: Repeatable feet-first free fall experiments were conducted in a laboratory mock-up environment using an instrumented Hybrid II 3-year-old test dummy. Impact surface type and fall height were varied to examine their influence on biomechanical measures.
Results: Feet-first falls from short distances (27
in.) (0.69
m) were found to have a low risk of contact-type head injury, regardless of impact surface type. When comparing different types of impact surfaces in a 27
in. (0.69
m) fall, head acceleration associated with falls onto playground foam was significantly less than that associated with falls onto wood, linoleum or padded carpet. For falls onto playground foam, femoral compressive loads and bending moments were found to significantly increase as fall height increased.
Conclusions: Impact surface type and fall height were found to influence biomechanics associated with injury risk in feet-first free falls as assessed through experimental mock-ups using an instrumented child test dummy. Feet-first falls from short distances (27
in.) (0.69
m) were associated with a low risk of contact-type head injury as assessed using HIC, irrespective of impact surface type.
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