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Ultra-high NH3 absorption by triazole cation-functionalized ionic liquids through multiple hydrogen bonding
No full textIonic liquids (ILs) are considered as prospective absorbents for NH3 separation and purification owing to extremely low vapor pressure, great affinity and structural tunability. Up to date, versatile ILs for NH3 absorption have been developed, but NH3 mass capacity of all the reported ILs or IL-based absorbents are still not comparable to that of traditional water absorbent. How to simultaneously improve NH3 mass capacity, selectivity and keep stable reversibility using IL absorbents is still a great challenge. In this work, the triazole cationfunctionalized ionic liquids (TCFILs) by introducing multiple protic H sites into N-heterocyclic cations were firstly designed and synthesized for enhancing NH3 absorption. These TCFILs showed superhigh NH3 mass capacity up to 0.365 g NH3/g IL at 30 degrees C and 1 bar, which is the maximum among the reported absorbents, and is even comparable to that of traditional water absorbent used in industrial. Moreover, the TCFILs also exhibited excellent selectivity of NH3/CO2 up to 182 and recycling stability. Such great comprehensive performances of NH3 absorption and separation were proved to originate from multiple hydrogen bonding between NH3 and protic hydrogens of the TCFIL cations. Therefore, this work will provide useful guidance to design competitive functionalized ILs for efficient and reversible absorption of NH3
Confinement amorphous cobalt-nickel oxide polyhedral yolk-shell structures for enhanced oxygen evolution performance
No full textMulti-scale regulation strategies ranging from electronic behavior regulation to crystal structure modulation to micro-nano structure construction can effectively improve the properties of materials, thereby bringing about significant improvements in performance. In this paper, we successfully constructed (Co1-xNix)3O4 with Ni substitution (x) unique polyhedral yolk-shell structure (PYSSs) electrocatalysts with confined amorphous regions, and achieved a significant improvement in the performance of oxygen evolution reaction (OER). The substitution of Ni can regulate the electronic coupling between metal sites, thereby optimizing the electronic configuration, creating abundant vacancy defects and enhancing the Co 3d-O 2p covalency. Meantime, the creation of confined amorphous regions can further increase the number of oxygen vacancies and unsaturated metal sites. Especially, the construction of the unique PYSSs structure can increase the effective specific surface area, hold the reaction intermediates for deeper reaction, accelerate the infiltration and transport of the electrolyte, prevent the adhesion of bubbles and accelerate the gas diffusion
Construction of Gemini composite based on TiO2 pillared montmorillonite for efficient oil-water separation
No full textOwing to the changeable components of oil-water system and the inflexible limitation of available materials during oil-water separation, the treatment of oily wastewater with wide pH, large discharge and high COD value remains a great challenge. In this study, a simple strategy was used to construct Gemini composite based on TiO2 pillared montmorillonite. The resultant montmorillonite-based Gemini composite (QATMt-x) exhibited high surface area (116.54 m2 g-1), surface potential (18.8 mV at pH2), good acid and alkali resistance, amphiphilicmultifunctional surface, and defective layered structure and, as a result, delivered high capability (ED >= 96 %) and long cyclic life for oil-water separation. More significantly, detailed mechanism studies reveal that the crucial reasons of oil-water separation on microemulsion and aqueous containing organic contaminant are demulsification through electron capture of the grafted chitosan, and adsorption by lipophilic saturated alkanes, titanium hydrates, (metal) hydroxyl and amine group, respectively. Hence, QATMt-x is particularly suitable for efficient demulsification in acidic media (pH 2) and for the adsorption of ecotoxic organic substances (e.g., perfluorooctanoic acid, methyl blue). In short, construction of Gemini surfactants based on low-cost inorganic carriers would offer new strategies in exploring amphipathic dual-functional layered structures for simultaneously efficient separation of multisystem oil-water scenarios
Trans-level multi-scale simulation of porous catalytic systems: Bridging reaction kinetics and reactor performance
No full textMulti-scale porous structures inside and/or between the catalyst pellets or particles are found in many chemical processes, where strong coupling of reaction and transport results in complex apparent reaction kinetics influ-ential to the reactor performance. Traditional continuum-based porous media models and simulation methods can hardly describe such structures and their scale effects faithfully. A trans-level multi-scale discrete compu-tational framework is hence proposed to address this complexity and implemented for an olefin catalytic cracking (OCC) process. The apparent reaction kinetics at the REV (representative elementary volume) scale is obtained by hard-sphere pseudo-particle modeling (HS-PPM), and coupled with computational fluid dynamics / discrete element method (CFD-DEM) for the reactor-level hydrodynamics via a one-dimensional (1D) finite difference scheme for particle-level diffusion. The mesoscales of the REVs and the flow networks between the particles are thus covered by the framework, which are previously described by simple average quantities in the continuum methods. The reactant conversion rate and target product selectivity obtained agree well with experimental results, while a continuum approach may give significantly different and unreasonable results. The multi-scale method is, therefore, demonstrated to be necessary and effective for bridging the intrinsic reaction kinetics with the performance of porous catalytic reactors
Cooperation Fund of the Institute of Clean Energy Innovation, Chinese Academy of Sciences[2021YFC2902500]
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Improving flotation separation of micro Si/SiC particles from silicon sawing waste by surface hydrophilic modification
No full textSilicon sawing waste (MSW) produced by mortar cutting causes serious environmental issues and a waste of highpurity silicon. The major obstacle in the recovery of high-purity silicon (Si) is the separation of microscale Si and silicon carbide (SiC) in MSW. In this study, micro Si/SiC in silicon sawing waste was separated effectively by bulk-oil flotation after surface hydrophilic modification of Si particles. The structural evolution of micro Si surface after wet oxidization in water and acid was characterized by FT-IR, TEM, and XPS. Specifically, the wet oxidization process reduced the contact angle from 63 +/- 0.3 degrees to 18.5 degrees of Si surface for the coating of an amorphous oxide with hydroxy groups on Si particles enhanced the wettability. The amorphous oxide layer with hydroxy coated on Si particles played a key role in enhancing the wettability of Si particles. The wet oxidization is essential to the subsequent flotation separation for the contact angle of SiC keeping at around 60.3 degrees. The wettability of silicon sawing waste was further examined by the absorption of diesel. The effects of pH value and solid concentration on separation efficiency were studied. The best result obtained was 95% in Si recovery and 97.1 wt% in Si purity
