查看更多>>摘要：? 2021Nanosize H-SOD particles were hydrothermally synthesized as seeds for the secondary growth of hydroxy-sodalite (H-SOD) zeolite membrane. The size and phase purity of H-SOD zeolite particles were carefully controlled by changing several hydrothermal conditions. Especially, NaOH concentration in the hydrothermal solution made a significant effect on the phase purity and particle size. The high phase purity particles with a mean diameter of 80 nm were successfully synthesized at a 3 M NaOH concentration and applied for secondary growth. Overall, uniform H-SOD zeolite membranes with various thicknesses (3, 7, and 9.5 μm) were prepared by varying secondary growth time. The 9.5 μm thick H-SOD zeolite membrane exhibited high H2/N2 permselectivity of 95 at 473 K and a transmembrane pressure of 0.3 MPa. And, the pervaporation performance was evaluated for 90 wt% methanol-water mixture at 423 K, an elevated temperature. It showed a high water/methanol separation performance; its water/methanol separation factor was 2726 and the total flux, 1.02 kg/m2h. The high small gases and water separation performances were because interparticular voids between the nano size seeds were small and the surface of seed layer was flat. Therefore, the secondary growth remained a continuous zeolite layer with few non-zeolitic pores. In the present work, it was well proven experimentally that application of nanosize seed is an effective option to prepare high performance zeolite membrane in H-SOD zeolite system.
查看更多>>摘要：? 2021 Elsevier Inc.Most widely used carbon-based materials feature a bulk framework tolerant of extreme pH and temperature conditions while maintaining physical robustness, electrical conductivity, and biological relevance due to its inherent nontoxicity. At the nanoscale, the study of porous carbons has been of interest because of the enhanced accessible surface area relative to nonporous analogues. The evolution of synthetic techniques has developed structural allotropes with tunable internal pore diameter averages spanning from sub-nanometer to micron-plus sizes. Within the mesopore range, surface chemical phenomena abide by a kinetic-limited ruleset (ignoring the effects of bulk diffusion, as they do not pertain to this size regime). Further, mesopores provide sufficient volume and surface area for hosting guest species, including metal nanoparticles (MNP), polymers, small organics, and enzymes. These two unique features of mesoporous carbon (MC) drive interest in surface modifications to create new physicochemical functionality to these systems and their hosted species. As a result, the evolution of surface modification techniques has been scattered to disparate niches across the literature. This review compiles the array of elegant methods by which these carbon systems are topically engineered.
查看更多>>摘要：? 2021Heavy metals are becoming a huge problem in the environment and lead is one of them. Lead is disposed into water systems from huge industries such as paint industry, mining, and electroplating. In this study, manganese oxide coated fly ash (MnO2-CFA) was synthesized and characterized. The BET surface area of CFA MnO2-CFA was 18.4196 m2/g, 3 times more than the raw CFA (5.9231 m2/g). Batch adsorption experiments indicated that the uptake of Pb2+ fitted well in a Elovich kinetics model while the adsorption isotherm best fitted the Langmuir model with a maximum adsorption capacity of 141 mg/g at 40 °C and a pH of 7. Thermodynamic parameters obtained proved that the adsorption of Pb2+ ions using the MnO2-CFA was endothermic and spontaneous. Furthermore, the adsorbent was highly selective towards Pb2+ in the presence of Mn2+, Zn2, Ni2+and Cd2+. The Pb2+ removal % from a real water sample spiked with 30 mg/L Pb2+ was found to be 83.33%. The spent adsorbent was further applied in latent fingerprint detection which showed that Pb2+-MnO2-CFA produced clearer latent finger print (LFP) images compared to MnO2-CFA. LFP images were still clear 8 days after application of the spent adsorbent, proving that Pb2+-MnO2-CFA is a promising labelling agent.
查看更多>>摘要：? 2021 Elsevier Inc.A composite hollow mesoporous MIL-101@Pd@ZIF-8-30min (HM-MIL@Pd@ZIF-30min) nanocatalyst with hollow core and stable shell was developed in this study. Hollow mesoporous MIL-101(HM-MIL) was hydrothermally synthesized and employed as the supports of Pd nanoparticles by adopting a facile HM-MIL-template strategy to make ZIF-8 crystals uniformly overgrew on HM-MIL-101@Pd microcrystal cores. The obtained core-shell catalyst possessed hollow mesoporous structure, and the shell layer of ZIF-8 had additional advantages of abundant Lewis basic sites for heterogeneous racemization reaction. Compared with unmodified HM-MIL@Pd and solid MIL-101(Cr)@Pd@ZIF-8 (S-MIL@Pd@ZIF-8), HM-MIL@Pd@ZIF-8-30min had higher racemic chemical activity (conv. 99%) and selectivity (sel. R-amide 94%) in one-pot dynamic kinetic resolution (DKR) reaction system of rac-1-phenethylamine. The catalyst showed excellent stability, and the conversion and selectivity reached 95% and 93% respectively after ten catalytic cycles.
查看更多>>摘要：? 2021In this work, 4-methylpyridinium chloride (4-MePy-Cl) ionic liquid grafted on nanoporous Mn/zeolite-Y was synthesized in several steps. First, Mn@zeolite-Y nanostructure was prepared by the metal exchange reaction of manganese (II) chloride with zeolite-NaY. This nanomaterial was then reacted consecutively with trimethoxysilylpropyl chloride and 4-methylpyridine to obtain multi-functional 4-MePy-Cl ionic liquid manganese nanocomposite (Mn/4-MePy-IL@ZY) for the first time. The structure of this nanoporous compound was confirmed using different characterization techniques such as FT-IR, FE-SEM, EDX, XRD, N2 adsorption-desorption (BET), and TGA analyses. To evaluate the catalytic performance, the catalyst obtained was successfully employed as a multi-functional and efficient nanocatalyst in the facile synthesis of 3-amino-1-aryl-5,10-dioxo-pyrazolo [(Jagadeesan, 2016; Srilakshmi and Saraf, 2018) 1,21,2-b]phthalazine-2-carbonitriles through the four-component reaction of phthalic anhydride, hydrazine hydrate, malononitrile and arylaldehydes under mild reaction conditions with excellent yields. One of the obvious advantages of this nanocatalyst is the presence of Lewis acid (Mn2+) and basic ionic liquid (4-MePy-Cl) sites on a nanoporous solid surface (multi-functional), which can be very useful and important in multi-component syntheses.
查看更多>>摘要：? 2021 Elsevier Inc.A sequence of phases between structural phases in ALPO4-5, commencing from the 4-coordinated aluminum atoms (tetrahedra) in the bare crystal, up to the formation of 6-coordinated (octahedra), and 5-coordinated (bipyramids) aluminum atoms upon the progressive increase of the sorbate water loading, was identified by means of density functional theory calculations, combined with Rietveld refinement of our measured XRD patterns, and produced a crystallographic information file (CIF) at 313 K and relative humidity 81.5%. We modeled the thermodynamics of the sorbed water at progressively increasing chemical potentials via grand canonical Monte Carlo computations, and explained, on the basis of the formed phases, the hysteresis loop which appears in the gravimetrically measured isotherms of the literature during the sorption-desorption cycles. Molecular dynamics simulations predicted the impact of the existence of hydrated phases on the sorbate water diffusivity; collective diffusivities at the linear response regime were also calculated and thereby, transport coefficients.
查看更多>>摘要：? 2021 Elsevier Inc.The indirect release of excessive amounts of poisonous dyes into water has drastically affected the environment. Thus, in this work, a method to remove dyes from industrial water was investigated using ecofriendly cubic inorganic–organic Zn metal–organic frameworks (CZM). In particular, the room-temperature one-pot synthesis of inorganic–organic Zn-MOF nanocubes with superior adsorption capacity for the removal of malachite green (MG) dye in wastewater samples was studied. The nanocubes featured intergrowing chains with highly accessible surface areas, and uniform micropores could trap MG dye from wastewater. The inorganic–organic frameworks exhibited excellent adsorption capacity for MG. The adsorption conditions, such as the solution pH, played a significant role in generating an active negatively charged surface throughout the Zn-MOF adsorbent, thereby yielding microporous surfaces with strong ability to interact with and take up MG dye. Adsorption experiments revealed the high capacity of CZM for MG removal (953.14 mg g?1), and this capacity was maintained even after multiple reuse cycles. The microporous CZM adsorbent demonstrated a simple and effective model for water purification and the management of industrial wastewater. To the best of our knowledge, this work is the first to report the usage of Zn-MOF adsorbents for the removal of MG dye in wastewater samples.
查看更多>>摘要：? 2021 Elsevier Inc.A series of hybrid coupling porous organic polymers (HC-3vPPh3-POLs) were designed and synthesized through copolymerizing any two of tris(4-vinphenyl) phosphine (p-3vPPh3), tris(3-vinphenyl) phosphine (m-3vPPh3) and tris(2-vinphenyl) phosphine (o-3vPPh3) in different proportions by solvothermal polymerization. The BET surface area of obtained HC-3vPPh3-POLs is varied from 534 to 1124 m2?g?1 while the pore volume is changed from 0.43 to 2.25 cm3?g?1, and the amount of micropores could also be regulated from 43.5 to 66.8%. The afforded Rh/HC-3vPPh3-POLs exhibit different conversions from 91% to 98%, selectivity to aldehyde from 79% to 90%, and the 1/b ratios from 4.0 to 11.1 (the ratio of the linear aldehydes to the branched aldehydes) by adjusting the PPh3 microenvironment and their quantities. The superior recyclability in an autoclave reactor and stability in a fixed-bed reactor of Rh/HC-3vPPh3-POLs demonstrate the excellent potential of this method in preparing functional materials for heterogeneous catalysis. Combined characterization methods were employed and demonstrated that P atoms from different vinyl functional PPh3 were uniformly dispersed and interacted with each other, leading to different structure and PPh3 microenvironment in HC-3vPPh3-POLs.
查看更多>>摘要：? 2021 Elsevier Inc.In viewing the serious environmental issues caused by microplastics and air pollution, it is of great significance to capture microplastics in water and harmful particulate matter (PM) in atmosphere for maintaining human health. In this study, we report the synthesis of porous composite membrane, which was fabricated using 1,4-phenyldimercaptans and 1,3,5-triacetylbenzene as building blocks via a click chemistry, for microplastics filtration and PM capture. By using polystyrene fluorescent microspheres with a diameter of 0.1 μm as simulated microplastics, the filtration efficiency of the as-resulted porous composite membrane (PCM) was measure to be 90.92% by fluorescence analysis. The results obtained from infrared microspectrography also show that the PCM has superior removal performance for microplastics in terms to urban domestic wastewater. In the case of PM capture, the removal efficiencies of PCM for PM2.5 and PM10 were measured as high as 99.90% ± 0.42% and 99.93% ± 0.26%, respectively. Moreover, its removal efficiency for PM can remain nearly unchanged within 30 h. Owing to the flexible kapok fibers as supporting layer of PCM, the PCM possesses good mechanical properties and could be prepared without limitation in size and shape on a large scale under mild conditions, thus showing great potential for practical applications of microplastic removal and PM capture.
查看更多>>摘要：? 2021In this study, an amidoxime-appended zirconium metal-organic framework [Zr6O4(OH)4(BDC-NHCH2CH2C(=N–OH)NH2)6](UiO-66-AO, BDC = 1,4-benzenedicarboxylate) for efficiently and rapidly removing uranium from aqueous solution was fabricated through post-modifications. The chemical structure and composition of original and modified UiO-66 MOFs were investigated in detail. The principal factors affecting the adsorption of U(VI) ions have been investigated, including pH of the aqueous solution, contact time, temperature, and coexisting cations through batch adsorption experiments. The adsorption kinetics conformed to the pseudo-second-order model. It was found that the maximum adsorption capacity reached 232.8 mg/g at pH 5.0 and 328 K based on the Langmuir isotherm. The thermodynamics parameters revealed that this adsorption process was spontaneous and endothermic. The sorption experiment in a simulated nuclear industry effluent demonstrated a high adsorption efficiency (about 95.3%) and selectivity toward uranium. The extended X-ray absorption fine structure (EXAFS) analysis revealed the coordination mechanism of amidoxime-appended UiO-66 and uranyl.
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