查看更多>>摘要：? 2022 The AuthorsIn this paper, a novel functional monomer, N-(pyrrolidin-2-ylmethyl) methacrylamide (PMMA), was synthesized. Using Co(II) ions as the template, 2,2-azoisobutyronitrile (AIBN) as the initiator, ethylene glycol dimethacrylate (EDGMA) as the crosslinking agent, twenty-seven Co(II) ion-imprinted composite membranes (Co(II)-PMMA-IICM1～27) and their corresponding non-imprinted composite membranes (PMMA-NICM1～27) were prepared. Additionally, the related parameters of the imprinting system were systematically optimized. Co(II) ion-imprinted composite membranes (Co(II)-PMMA-IICM16) were prepared using Nylon-6 as the supporting membrane, which was soaked in a pre-polymerized solution of N,N-dimethylformamide and water (DMF: H2O (v/v) = 1: 1) for 180 s, using a molar ratio of template, monomer, and crosslinker of 1: 4: 50. The obtained material had a higher adsorption capacity (Qe = 428.24 mg g?1) and imprinting factor (IF = 2.36). The surface and internal porosity of Co(II)-PMMA-IICM16 were characterized by scanning electron microscopy and a nitrogen adsorption apparatus. In addition, it was found that the adsorption process of Co(II)-PMMA-IICM16 prepared under optimal conditions was better described by a Langmuir isotherm adsorption model, which verified that the adsorption involved monolayer adsorption. The kinetics data was more closely fit by a pseudo-second-order kinetics model, indicating that this adsorption process proceeded via chemisorption. The permeation experiments indicated that a “delayed” permeation mass transfer mechanism also occurred (β(Co(II)/Cd(II)) = 2.11 and β(Co(II)/Cu(II)) = 1.55). The Co(II) ion-imprinted composite membrane prepared in this paper demonstrated a relatively better imprinting effect, a specific recognition ability for template ions, and good selective permeability. These results validated that the design of this novel functional monomer was reasonable, and that it has potential applications in various fields where adsorption is necessary.
查看更多>>摘要：? 2022 Elsevier Inc.Utilization of porous materials such as metal-organic frameworks (MOFs) will get enhanced if a connectivity between the micro- and meso-pore structures within such solids can be achieved. Soft-templated synthesis has been a widely used method where surfactant based molecular self-assemblies act as templates to introduce mesopores in the intrinsically microporous MOFs and thereby generate hierarchical porosity (HP). In this work, we present our investigations on the formation of HP HKUST-1 MOFs by using two gemini surfactants, G16 and G14 as soft-templates. Crystal nucleation and growth conditions in the soft-templated synthesis play a significant role in the success of HP formation. Here, we have employed variations in the composition of water:ethanol (W:E) solvent mixtures mainly to understand and to arrive at the favourable templation conditions. Depending on the relative ratio of the W:E compositions and the gemini surfactants, we have employed additional parameters such as temperature, reaction time and reactant compositions that crucially influence the nucleation and growth factors to achieve HP. Gas sorption, DLS, zeta potential, thermogravimetry, SEM and TEM investigations indicate the formation of unique types of HP structures including the ones which have formed via bilayer and vesicular based soft-templation mechanism in our samples. Presence of the mesopores in our HP samples have been demonstrated by correlating the higher values of both the hierarchy factor (HF) and dye-sorption with a bulky Rhodamine molecule. A direct relation found between the HF values and the dye-uptake in our HP samples indicate that HF can be used as a quantitative marker of HP.
查看更多>>摘要：? 2022 The AuthorsThe worldwide spread of the SARS-CoV-2 virus has continued to accelerate, putting a considerable burden on public health, safety, and the global economy. Taking into consideration that the main route of virus transmission is via respiratory particles, the face mask represents a simple and efficient barrier between potentially infected and healthy individuals, thus reducing transmissibility per contact by reducing transmission of infected respiratory particles. However, long-term usage of a face mask leads to the accumulation of significant amounts of different pathogens and viruses onto the surface of the mask and can result in dangerous bacterial and viral co-infections. Zeolite imidazolate framework-8 (ZIF-8) has recently emerged as an efficient water-stable photocatalyst capable of generating reactive oxygen species under light irradiation destroying dangerous microbial pathogens. The present study investigates the potential of using ZIF-8 as a coating for face masks to prevent the adherence of microbial/viral entities. The results show that after 2 h of UV irradiation, a polypropylene mask coated with ZIF-8 nanostructures is capable of eliminating S. Aureus and bacteriophage MS2 with 99.99% and 95.4% efficiencies, respectively. Furthermore, low-pathogenic HCoV-OC43 coronavirus was eliminated by a ZIF-8-modified mask with 100% efficiency already after 1 h of UV irradiation. As bacteriophage MS2 and HCoV-OC43 coronavirus are commonly used surrogates of the SARS-CoV-2 virus, the revealed antiviral properties of ZIF-8 can represent an important step in designing efficient protective equipment for controlling and fighting the current COVID-19 pandemic.
查看更多>>摘要：? 2022 Elsevier Inc.Pore structure of Polyethyleneimine (PEI)/SBA-15 nanocomposites was investigated by Positron Annihilation Lifetime Spectroscopy (PALS) in conjunction with other conventional means like TEM, XRD and N2 adsorption and desorption techniques. In this study, PALS could help us obtain the information of micropores and mesopores in the SBA-15 matrix at same time via analyzing the change of long lifetime components τ3 and τ4. The size of micropores and mesopores could be obtained based on theoretical models, which is slightly smaller than the mesopore size obtained by N2 adsorption and desorption techniques due to the existence of open micropores in the channel. This provides unique tool for understanding the evolution of the nanometer-sized pores in SBA-15 and PEI/SBA-15 composites and quantitative description of the relationship between the materials structure and its CO2 adsorption capacity in the future.
查看更多>>摘要：? 2022The application of ceramic mesoporous membranes is mainly limited by the trade-off between separation performance and fabrication cost. Here, a co-sintering technique is employed to fabricate ZrO2 dual-layer ceramic mesoporous membranes with high separation precision and water permeance. Based on a coarse ceramic substrate, dual layers that could effectively decrease the fabrication cost and time were co-sintered. By doping zirconia nanoparticles in the sublayer, the sintering temperature could be decreased, and a high bonding strength was achieved between the dual layers. It is demonstrated that the permeance can be finely tuned by controlling the thickness of the sublayer. The resulting membrane exhibited a high water permeance of 280 L m?2 h?1 bar?1 and a molecular weight cut-off of 40–50 kDa. The zirconia mesoporous membrane was employed for sol separation, affording a 100% rejection rate toward SiO2 nanoparticles. The cost-effective ZrO2 mesoporous membrane exhibits significant application potential for the separation of industrial SiO2 sols.
查看更多>>摘要：? 2022 Elsevier Inc.The production of n-butyric acid (n-BA) through microbial fermentation has attracted considerable attention owing to the potential to reduce the carbon footprint via the recycling of carbon biomass sources. However, the industrial use of n-BA produced via fermentation involves its separation and recovery, which require energy-intensive extraction processes. We explore the possibility of recovering n-BA with different types of zeolite adsorbents. Whereas Silicalite-1 (MFI), Zeolite 4A (LTA), and Zeolite Y (FAU) preferentially adsorb n-BA, [OH]_Silicalite-1 exhibits higher n-BA/acetic acid (AA) and n-BA/propionic acid (PA) selectivities (approximately 3.11 and 2.08, respectively). These results indicate that the selective adsorption of n-BA by zeolites is mainly driven by intermolecular interactions that depend on the molecular weight of the adsorbates, whereas their hydrophobicity hinders the adsorption of the more polar AA and PA. Lowering the pH values of fermentation broths suppresses the deprotonation of n-BA, thereby promoting n-BA adsorption by zeolites. Moreover, [F]_Silicalite-1 with fewer defective silanol groups and nests exhibits improved n-BA/AA and n-BA/PA selectivities (approximately 7.80 and 3.10, respectively); adsorbents made from [F]_Silicalite-1 demonstrate excellent recyclability and negligible adsorption of bulky glucose. According to the comparison of the extraction methods, [F]_Silicalite-1 has a distinctly higher selectivity for n-BA at low concentrations in mixtures. Thus, zeolite adsorbents can either be used as individual separation units for mixtures with low n-BA concentrations or retrofitted for already existing extraction processes.
查看更多>>摘要：? 2022 Elsevier Inc.The aluminum (Al) pairs in the ZSM-5 zeolite framework are recognized as an important acid site for a variety of reactions. However, knowledge of how to prepare ZSM-5 zeolites with adjustable Al pairs contents is still lacking. In this work, the impact of the Al species state and concentration on the content of the Al pairs in the preparation of ZSM-5 zeolite was studied. First, we prepared ZSM-5 zeolites with the same SDA (TPAOH), Si source (TEOS), and crystallization condition but with different Al sources (aluminum nitrate, aluminum sulfate, aluminum chloride, aluminum hydroxide, and sodium aluminate). The Raman spectra indicated that the state of the Al species in the silicon aluminum mixture differs for Al[(OH2)6]3+ and Al(OH)4–. Although the prepared ZSM-5 zeolites have similar Si/Al molar ratios, the silicon aluminum mixture with Al(OH)4– is more likely to form Al pairs than the silicon aluminum mixture with Al[(OH2)6]3+ (74% vs. 52%). This conclusion was further proven by well-designed control experiments. For experiments with the same Al source (aluminum sulfate), SDA (TPAOH), Si source (TEOS), and crystallization condition, the conversion of the Al species from Al[(OH2)6]3+ to Al(OH)4– was achieved by the addition of NaOH. Under similar Si/Al molar ratios, ZSM-5 zeolites with Al pairs contents ranging from 44% to 82% were prepared. In addition, ZSM-5 zeolites were synthesized under different water contents. The lower the water content, the more Al pairs were formed (68% vs. ～78%). In summary, the state of the Al species is an important factor in determining the content of the Al pairs when preparing ZSM-5 zeolites.
查看更多>>摘要：? 2022 Elsevier Inc.Ultrafast synthesis of nanosized and submicron zeolite materials is challenging but highly desired due to their wide applications. Herein, discrete LTA-type aluminophosphate molecular sieve (AlPO4-LTA) submicron crystals have been synthesized in an open glass beaker under oil bath heating for only 10 min. The influences of the synthesis parameters, including the ratios of tetramethylammonium hydroxide (TMAOH)/Al and HF/Al, and the heating methods were investigated thoroughly. The optimized product exhibits exceptional properties, including good crystallinity, small particle size (ca. 130 nm) and large BET surface areas (867 m2/g). The time-dependent study reveals the formation process of submicron AlPO4-LTA crystals: the primary worm-like amorphous first aggregated into loosely assembled spheres, then the crystallinity of the spheres enhances while keeping the particle size unchanged. Using the submicron AlPO4-LTA crystals as the seed layer, an AlPO4-LTA membrane was synthesized via secondary growth approach. For binary mixtures at 298 K, the separation factors for H2/N2, H2/O2, H2/CO2 and H2/CH4 are 4.8, 6.2, 7.3 and 5.9, respectively, suggesting the good gas separation performance of the membrane.
查看更多>>摘要：? 2022Bio-MOF-1 is a kind of metal-organic frameworks (MOFs) with bio-derived constitution, self-fabricated by zinc-adeninate secondary building units (SBUs) and may theoretically be endowed with biocompatible behaviors. Its biological applications currently contain several small molecule drugs delivery and in vitro mineralization, yet the related evidence on its biosafety and biocompatibility is still in great need. With the aid of self-modified protocol to synthesize micro/nanoscale bio-MOF-1 (m/n-bio-MOF-1), this study aimed to implement a systematic evaluation based on a series of tests from different dimensions including cell proliferation, oxidative stress, apoptosis and animal experiment, etc. These in vitro & in vivo biosafety and biocompatibility tests are to provide fresh evidence and advice for further applications. The outcomes indicated a concentration-dependent trend that 50 and 20 μg/mL groups proved biofriendly, with n-bio-MOF-1 surpassing m-bio-MOF-1. In conclusion, this work provided systematic evidence for the biosafety of m/n-bio-MOF-1, paved the way for their further exploration, and appealed more emphasis on MOFs toxicity.
Lima E.T.L.do Nascimento L.A.S.Zamian J.R.da Costa C.E.F....
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查看更多>>摘要：? 2022 Elsevier Inc.In this study, SAPO-5 having a high silicon content was synthesized and further modified by functionalization with sulfonic acid groups using 3-mercaptopropyltrimethoxysilane (MTPS) as a precursor. In particular, we focused on the effect of water on the organofunctionalization process using SAPO-5 either dehydrated under vacuum (S5–SO3H/Vac) or without any thermal pretreatment (S5–SO3H). Using X-ray diffractometry, inductively coupled plasma–optical emission spectroscopy, elemental analysis of carbon, nitrogen, hydrogen and sulfur, thermogravimetric analysis, Fourier transform infrared spectroscopy, and 29Si, 27Al, 31P, and 13C NMR spectroscopy, it was possible to identify important structural differences in the obtained hybrid materials. The results showed that S5–SO3H has a Si:S molar ratio five times larger than that of S5–SO3H/Vac. The presence of Tm sites (organic-modified silica sites, Si–C bonds), as revealed by 29Si MAS-NMR measurements, suggests that the organic pending groups are bonded covalently to the Si–OH groups in the SAPO-5 network during silanization. Further differences between the material obtained under dry conditions and that prepared from hydrated SAPO-5 were revealed by measuring the acidity via potentiometric titration: S5–SO3H was 40% more acidic than S5–SO3H/Vac. Both materials were also tested for their catalytic oleic acid esterification ability. Although the turnover frequency of S5–SO3H/Vac was four times higher than that of S5–SO3H, its conversion after five sequential cycles dropped from 97.4 to 28.3%. In contrast, S5–SO3H yielded a conversion of 84.4%, starting from 99.4%, after the same number of cycles; thus, microporous SAPO-5 is a promising catalyst support for reactions involving bulky molecules such as oleic acid.
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Elsevier