994 research outputs found

    Electromembrane Processes: Experiments and Modelling

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    The increasing demand for water and energy poses technological challenges to the implementation of efficient concepts for a sustainable development. In this perspective, electromembrane processes (EMPs) can play a crucial role in green chemistry schemes oriented towards circular economy approaches and renewable energy systems. EMPs are based on the use of ion-exchange membranes under the action of an electric field. Versatility, selectivity, high recovery, and chemical-free operations are their main strengths. Experimental campaigns and modelling tools are prompting the improvement of consolidated processes and the development of novel concepts. Several application fields have been proposed (in chemical, food, pharmaceutical industries, and others) including desalination, water and wastewater treatment, recovery of valuable products, concentration and purification operations, chemical production, and energy production and storage. This book is a collection of the scientific contributions in the Special Issue Processes: Experiments and Modelling from the journal Membranes. It is focused on recent advancements in EMPs and their applications based on the development of cutting-edge engineered systems via experiments and/or models

    Electromembrane Processes: Experiments and Modelling

    Get PDF
    The increasing demand for water and energy poses technological challenges to the implementation of efficient concepts for a sustainable development. In this perspective, electromembrane processes (EMPs) can play a crucial role in green chemistry schemes oriented towards circular economy approaches and renewable energy systems. EMPs are based on the use of ion-exchange membranes under the action of an electric field. Versatility, selectivity, high recovery, and chemical-free operations are their main strengths. Experimental campaigns and modelling tools are prompting the improvement of consolidated processes and the development of novel concepts. Several application fields have been proposed (in chemical, food, pharmaceutical industries, and others) including desalination, water and wastewater treatment, recovery of valuable products, concentration and purification operations, chemical production, and energy production and storage. This book is a collection of the scientific contributions in the Special Issue Processes: Experiments and Modelling from the journal Membranes. It is focused on recent advancements in EMPs and their applications based on the development of cutting-edge engineered systems via experiments and/or models

    Electromembrane Processes: Experiments and Modelling

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    Electromembrane processes offer a multitude of applications, allowing for the recovery of water, other products, and energy. This book is a collection of contributions on recent advancements in electromembrane processes attained via experiments and/or models. The first paper is a comprehensive review article on the applications of electrodialysis for wastewater treatment, highlighting current status, technical challenges, and key points for future perspectives. The second paper focuses on ZSM-5 zeolite/PVA mixed matrix CEMs with high monovalent permselectivity for recovering either acid or Li+. The third paper regards direct numerical simulations of electroconvection in an electrodialysis dilute channel with forced flow under potentiodynamic and galvanodynamic regimes. The fourth paper investigates the reasons for the formation and properties of soliton-like charge waves in overlimiting conditions. The fifth paper focuses on the characterization of AEMs functionalized by surface modification via poly(acrylic) acid yielding monovalent permselectivity for reverse electrodialysis. In the sixth paper, CFD simulations of reverse electrodialysis systems are performed. The seventh paper proposes an integrated membrane process, including electrochemical intercalation–deintercalation, for the preparation of Li2CO3 from brine with a high Mg2+/Li+ mass ratio. Finally, the eighth paper is a perspective article devoted to the acid–base flow battery with monopolar and bipolar membranes

    Passive micromixers and organic electrochemical transistors for biosensor applications

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    Fluid handling at the microscale has greatly affected different fields such as biomedical, pharmaceutical, biochemical engineering and environmental monitoring due to its reduced reagent consumption, portability, high throughput, lower hardware cost and shorter analysis time compared to large devices. The challenges associated with mixing of fluids in microscale enabled us in designing, simulating, fabricating and characterizing various micromixers on silicon and flexible polyester substrates. The mixing efficiency was evaluated by injecting the fluids through the two inlets and collecting the sample at outlet. The images collected from the microscope were analyzed, and the absorbance of the color product at the outlet was measured to quantify the mixing efficacy. A mixing efficiency of 96% was achieved using a flexible disposable micromixer. The potential for low-cost processing and the device response tuning using chemical doping or synthesis opened doorways to use organic semiconductor devices as transducers in chemical and biological sensor applications. A simple, inexpensive organic electrochemical transistor (OECT) based on conducting polymer poly(3,4- ethyelenedioxythiphene) poly(styrene sulfonate) (PEDOT:PSS) was fabricated using a novel one step fabrication method. The developed transistor was used as a biosensor to detect glucose and glutamate. The developed glucose sensor showed a linear response for the glucose levels ranging from 1 ÎŒM-10 mM and showed a decent response for the glucose levels similar to those found in human saliva and to detect glutamate released from brain tumor cells. The developed glutamate sensor was used to detect the glutamate released from astrocytes and glioma cells after stimulation, and the results are compared with fluorescent spectrophotometer. The developed sensors employ simple fabrication, operate at low potentials, utilize lower enzyme concentrations, do not employ enzyme immobilization techniques, require only 5 ÎŒL of both enzyme and sample to be tested and show a stable response for a wide pH ranging from 4 to 9

    Role of Surface Chemistry in Nanoscale Electrokinetic Transport

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    This dissertation work presents the efforts to study the electrofluidics phenomena, with a focus on surface charge properties in nanoscale systems with the potential applications in imaging, energy conversion, ultrafiltration, DNA analysis/sequencing, DNA and protein transport, drug delivery, biological/chemical agent detection and micro/nano chip sensors. Since the ion or molecular or particle transport and also liquid confinement in nano-structures are strongly dominated by the surface charge properties, in regards of the fundamental understanding of electrofluidics at nanoscale, we have used surface charge chemistry properties based on 2-pK charging mechanism. Using this mechanism, we theoretically and analytically showed the surface charge properties of silica nanoparticles as a function of their size, pH level and salt ionic strength of aqueous solution. For a fixed particle size, the magnitude of the surface charge typically increases with an increase in pH or background salt concentration. Furthermore, we investigated the surface charge properties of a charged dielectric nanoparticle and flat wall in electrostatic interactions. According to the theoretical results strong interactions cause a non-uniform surface charge density on the nanoparticle and the plate as a result of the enhancement of proton concentration in the gap between the particle and the plate. This effect increases with decreased separation distance (Kh). We moreover investigated the ion confinement inside the nanospaces and using a continuum model, we showed the proton enhancement in extended nanochannels. The proton enrichment at the center of the nanochannel is significant when the bulk pH is medium high and the salt concentration is relatively low. The results gathered are informative for the development of biomimetic nanofluidic apparatuses and the interpretation of relevant experimental data. Later, we have developed an analytical model for electroosmotic ion transport inside pH-regulated nanoslits and compared the results with the numerical study. We showed the influences of background salt concentration, pH level and the length of nanoslit on EOF velocity. The predictions show that the EOF velocity increases first and then decrease with background salt concentration increasing and the EOF velocity increases with pH level of aqueous solution

    Towards scale‐up of graphene production via nonoxidizing liquid exfoliation methods

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    Graphene, the two‐dimensional form of carbon, has received a great deal of attention across academia and industry due to its extraordinary electrical, mechanical, thermal, chemical, and optical properties. In view of the potential impact of graphene on numerous and diverse applications in electronics, novel materials, energy, transport, and healthcare, large‐scale graphene production is a challenge that must be addressed. In the past decade, top–down production has demonstrated high potential for scale‐up. This review features the recent progress made in top–down production methods that have been proposed for the manufacturing of graphene‐based products. Fabrication methods such as liquid‐phase mechanical, chemical and electrochemical exfoliation of graphite are outlined, with a particular focus on nonoxidizing routes for graphene production. Analysis of exfoliation mechanisms, solvent considerations, key advantages and issues, and important production characteristics including production rate and yield, where applicable, are outlined. Future challenges and opportunities in graphene production are also highlighted

    Recent Advances on Electrochemical Sensors for the Detection of Organic Disinfection Byproducts in Water

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    Irreversible organ damage or even death frequently occurs when humans or animals unknowingly drink contaminated water. Therefore, in many countries drinking water is disinfected to ensure removal of harmful pathogens from drinking water. If upstream water treatment prior to disinfection is not adequate, disinfection byproducts (DBPs) can be formed. DBPs can exist as wide variety of compounds, but up until now, only several typical compounds have drinking water standards attributed to them. However, it is apparent that the range of DBPs present in water can comprise hundreds of compounds, some of which are at high enough concentrations to be toxic or potentially carcinogenic. Hence, it becomes increasingly significant and urgent to develop an accessible, affordable, and durable sensing platform for a broader range and more sensitive detection of DBPs. Compared with well-established laboratory detection techniques, electrochemical sensing has been identified as a promising alternative that will provide rapid, affordable, and sensitive DBP monitoring in remote water sources. Therefore, this Review covers current state-of-the-art development (within the past decade) in electrochemical sensing to detect organic DBPs in water, which covered three major aspects: (1) recognition mechanism, (2) electrodes with signal amplification, and (3) signal read-out techniques. Moreover, comprehensive quality assessments on electrochemical biosensors, including linear detection range, limit of detection (LoD) and recovery, have also been summarized
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