5 research outputs found

    Metal-organic framework hybrid adsorbents for carbon capture - A review

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    Metal-organic frameworks (MOFs) are three-dimensional network structures synthesized by the assembly of organic ligands with metal ions or clusters. They currently constitute one of the most promising adsorbent categories for CO2 capture given their high specific surface area and porosity, chemical versatility, and facile chemistry supporting strategic structural modifications. Indeed, many thousands of MOFs are referenced in various structural databases. Within this wide family of materials, many experience certain challenges, which often limit their use for practical applications, including their relatively poor thermal and chemical stability, cyclability, and sensitivity to trace contaminants. One promising approach to address these drawbacks lies with the hybridization of MOFs with other material counterparts to design combinatorial hybrid adsorbents exhibiting superior performance and enhanced properties, benefiting from synergetic effects from each component and interfacial properties engineering. The purpose of this work is to critically review hybridized MOF adsorbents for CO2 capture, with a prime focus on the different opportunities offered by hybridizing materials and additives to MOFs. The engineering, properties, and performance of hybridized MOFs are systematically reviewed, and opportunities and challenges are discussed. This work provides key parameters of the application of hybridized MOF adsorbents and presents recommendations for further research, thereby providing a roadmap for the synthesis and usage of these types of adsorbents for practical CO2 capture applications

    Removal of natural organic matter from surface water sources by nanofiltration and surface engineering membranes for fouling mitigation – A review

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    Given that surface water is the primary supply of drinking water worldwide, the presence of natural organic matter (NOM) in surface water presents difficulties for water treatment facilities. During the disinfection phase of the drinking water treatment process, NOM aids in the creation of toxic disinfection by-products (DBPs). This problem can be effectively solved using the nanofiltration (NF) membrane method, however NOM can significantly foul NF membranes, degrading separation performance and membrane integrity, necessitating the development of fouling-resistant membranes. This review offers a thorough analysis of the removal of NOM by NF along with insights into the operation, mechanisms, fouling, and its controlling variables. In light of engineering materials with distinctive features, the potential of surface-engineered NF membranes is here critically assessed for the impact on the membrane surface, separation, and antifouling qualities. Case studies on surface-engineered NF membranes are critically evaluated, and properties-to-performance connections are established, as well as challenges, trends, and predictions for the field's future. The effect of alteration on surface properties, interactions with solutes and foulants, and applications in water treatment are all examined in detail. Engineered NF membranes containing zwitterionic polymers have the greatest potential to improve membrane permeance, selectivity, stability, and antifouling performance. To support commercial applications, however, difficulties related to material production, modification techniques, and long-term stability must be solved promptly. Fouling resistant NF membrane development would be critical not only for the water treatment industry, but also for a wide range of developing applications in gas and liquid separations

    Applications of nano-porous graphene materials-critical review on performance and challenges

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    The design and fabrication of 2D nano-porous architectures with controllable porosity and pore structure, as well as unique properties at the nanoscale are critical for applications such as separation, sensing, energy and catalysis. Perforation strategies across 2D materials, primarily graphene, have shown promising opportunities to develop nanostructures with tunable ranges of pore size distribution, pore density and uniformity. In addition, the perforated graphene structures exhibit improved properties in terms of plasmonic diffusion, catalytic activity and thermo-electrical properties compared to dense 2D materials and are opening new avenues for the development of responsive or reactive materials. This review presents and discusses the very recent developments in the synthesis of perforated graphene-based materials and correlates the morphology and other properties of such 2D nano-porous materials to their performance in applications such as separation, sensing and energy. Challenges related to the controlled engineering and manufacturing of such nanostructures particularly from a scalability point of view, as well as potential avenues for performance improvements through alternative 2D perforated materials are also critically evaluated

    Hybrid salt-enriched micro-sorbents for atmospheric water sorption

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    Water shortage severely impacts drought-stricken regions, with estimates indicating that almost half a billion people are affected yearly. Composites of Salt and Porous Matrix (CSPMs) are promising functional materials for water vapor sorption. Here, CSPMs were synthesized by loading SAPO-34 porous crystals with highly hygroscopic salts, namely LiCl and CaCl2, individually (mono-salt systems) or combined (binary salt systems) to enhance water sorption capacity and cyclability. The LiCl and CaCl2 content in the impregnation solution impacted the sorption behavior and equilibrium capacity of the resulting composites. Physicochemical, morphological, textural, and sorption properties were evaluated showing that the confinement of binary salts yielded the highest water uptake (0.88 gw/gads at 25 °C and 90 % RH), which was four times higher than that of the parent SAPO-34. The shape of the obtained water vapor isotherms revealed that the salts introduced into the porous structure led to significant changes in the sorption mechanism, with SAPO-34 following a Langmuir behavior (type I isotherm) and the composites a type II isotherm with associated multilayer formation due to the presence of the salts. Kinetic studies also revealed that the materials follow a PSO model dominated by water-surface interactions. Embedding different salts into the same hosting pores to support atmospheric water harvesting was therefore found to enhance capacity and cyclability compared to single inorganic porous structures toward more efficient water sorption processes

    A surface-tethered dopant method to achieve 3D control over the growth of a nanometers-thin and intrinsically transparent polypyrrole film

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    The electrochemical growth of conductive polymer films is a convenient synthesis route but challenging to control due to local variability in the reaction kinetics. Here we report a new method for electropolymerizing highly reproducible conductive polypyrrole films that are just nanometers thick, highly conductive and possess intrinsic optical transparencies comparable to ITO. The synthesis method utilizes a surface-tethered dopant molecule, in this case a self-assembled monolayer of the highly anionic protein lubricin (LUB), to template and thus control the 3-dimensional growth of the polypyrrole when the electrochemical polymerization reaction is performed in a pyrrole monomer solution containing no additional dopant molecules or ions. Because the tethered dopant controls where and how much polypyrrole growth occurs, this method effectively decouples the fine film morphology, thickness, and spatial-growth from the polymerization reaction kinetics and represents a paradigm shift in the electrochemical polymerization of conductive polymer films
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