Metal-Organic Frameworks

金属 - 有机框架
  • 文章类型: Journal Article
    随着我国各种疾病发病率的不断上升和医药行业的不断发展,对氟沙星型抗生素的需求不断增长。由于生产规模大,垃圾处理成本高,母体药物及其代谢物不断通过生活污水进入水环境,生产废水,和其他途径。近年来,氟沙星对水生环境的污染日益严重,使水环境中氟沙星的降解技术成为环境科学领域的研究热点。金属有机骨架(MOFs),作为一种新型的多孔材料,近年来引起了很多关注。在本文中,四种光催化材料,MIL-53(Fe),NH2-MIL-53(Fe),MIL-100(Fe),和g-C3N4合成并应用于氧氟沙星和恩诺沙星的去除研究。其中,MIL-100(Fe)材料表现出最佳的光催化效果。在可见光下3h后,氧氟沙星的降解效率达到95.1%,恩诺沙星基本完全降解。研究了不同材料对氟沙星可见光催化降解的影响。此外,恩诺沙星和氧氟沙星的光催化机理是通过使用三个捕集器(■O2-,h+,and▪OH),证明·O2-的作用促进了光催化下材料的降解效果。
    With the rising incidence of various diseases in China and the constant development of the pharmaceutical industry, there is a growing demand for floxacin-type antibiotics. Due to the large-scale production and high cost of waste treatment, the parent drug and its metabolites constantly enter the water environment through domestic sewage, production wastewater, and other pathways. In recent years, the pollution of the aquatic environment by floxacin has become increasingly serious, making the technology to degrade floxacin in the aquatic environment a research hotspot in the field of environmental science. Metal-organic frameworks (MOFs), as a new type of porous material, have attracted much attention in recent years. In this paper, four photocatalytic materials, MIL-53(Fe), NH2-MIL-53(Fe), MIL-100(Fe), and g-C3N4, were synthesised and applied to the study of the removal of ofloxacin and enrofloxacin. Among them, the MIL-100(Fe) material exhibited the best photocatalytic effect. The degradation efficiency of ofloxacin reached 95.1% after 3 h under visible light, while enrofloxacin was basically completely degraded. The effects of different materials on the visible photocatalytic degradation of the floxacin were investigated. Furthermore, the photocatalytic mechanism of enrofloxacin and ofloxacin was revealed by the use of three trappers (▪O2-, h+, and ▪OH), demonstrating that the role of ▪O2- promoted the degradation effect of the materials under photocatalysis.
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  • 文章类型: Journal Article
    背景:纳米酶,一类新的纳米材料,由于其出色的稳定性,已成为生物传感器设计中酶的有希望的替代品,负担能力,和准备的可用性。虽然纳米酶解决了天然酶的许多限制,他们仍然面临挑战,特别是在达到其天然对应物的催化活性水平。这表明需要增强基于纳米酶的生物传感器的灵敏度。通过调节纳米酶的大小可以显著提高其催化活性,形态学,和纳米材料的表面组成。
    结果:在这项工作中,设计了一种中空核壳结构以增强纳米酶的催化活性。中空核壳结构材料由纳米酶核层组成,一个空心层,和MOF壳层。以经典的过氧化物酶如Fe3O4为例,一种新型纳米酶@MOF的开发,特别是p-Fe3O4@PDA@ZIF-67,展示了其在增强基于Fe3O4纳米酶的传感器灵敏度方面的应用。这种创新的纳米复合材料,MOF层设计用于吸附传感器的信号分子,以提高纳米酶催化反应产生的活性氧的利用率,中空层设计用于防止纳米酶的活性位点被MOF层覆盖。手稿强调了纳米复合材料在检测过氧化氢(H2O2)方面的卓越灵敏度,再加上高特异性和可重复性,即使在牛奶样品等复杂环境中。
    这项工作首次提出并证明了具有中空层结构的Fe3O4纳米酶@MOF旨在提高Fe3O4纳米酶的催化活性和基于Fe3O4纳米酶的传感器的灵敏度。这项研究标志着纳米酶技术的重大进步,展示结构创新在创造高性能方面的潜力,敏感,和稳定的生物传感器的各种应用。
    BACKGROUND: Nanozymes, a new class of nanomaterials, have emerged as promising substitutes for enzymes in biosensor design due to their exceptional stability, affordability, and ready availability. While nanozymes address many limitations of natural enzymes, they still face challenges, particularly in achieving the catalytic activity levels of their natural counterparts. This indicates the need for enhancing the sensitivity of biosensors based on nanozymes. The catalytic activity of nanozyme can be significantly improved by regulating its size, morphology, and surface composition of nanomaterial.
    RESULTS: In this work, a kind of hollow core-shell structure was designed to enhance the catalytic activity of nanozymes. The hollow core-shell structure material consists of a nanozymes core layer, a hollow layer, and a MOF shell layer. Taking the classic peroxidase like Fe3O4 as an example, the development of a novel nanozyme@MOF, specifically p-Fe3O4@PDA@ZIF-67, is detailed, showcasing its application in enhancing the sensitivity of sensors based on Fe3O4 nanozymes. This innovative nanocomposite, featuring that MOF layer was designed to adsorb the signal molecules of the sensor to improve the utilization rate of reactive oxygen species generated by the nanozymes catalyzed reactions and the hollow layer was designed to prevent the active sites of nanozymes from being cover by the MOF layer. The manuscript emphasizes the nanocomposite\'s remarkable sensitivity in detecting hydrogen peroxide (H2O2), coupled with high specificity and reproducibility, even in complex environments like milk samples.
    UNASSIGNED: This work firstly proposed and proved that Fe3O4 nanozyme@MOF with hollow layer structure was designed to improve the catalytic activity of the Fe3O4 nanozyme and the sensitivity of the sensors based on Fe3O4 nanozyme. This research marks a significant advancement in nanozyme technology, demonstrating the potential of structural innovation in creating high-performance, sensitive, and stable biosensors for various applications.
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  • 文章类型: Journal Article
    尽管过去的一系列研究证明了铁基金属有机骨架(MOFs)作为光催化剂的潜在用途,光催化机理的知识差距来自于分离同时吸附和光催化降解的挑战。因此,本文旨在提出一种新的方法,通过在光催化过程中解吸目标分子来挖掘吸附和光催化降解的潜在机制。在这项研究中,两种铁基MOFs,选择MIL-101(Fe)和MIL-101(Fe)-NH2在可见光照射下去除氯纤酸。在光催化之前,基于吸附动力学揭示了吸附机理,等温线,热力学解释,及其对溶液pH值的依赖性。结果推断,主要的吸附机理是通过氯贝酸的苯环与铁基MOFs的有机配体之间的π-π相互作用。基于这些结果,在氯贝特酸的光催化降解过程中,光催化机理可以独立或联合评估。随后,Tauc方法和XPS光谱的应用表明,铁基MOFs的带隙结构具有通过可见光照射下电子激发产生ROS来氧化环纤酸的潜力。最重要的是,铁基MOF的胺官能化改变了结构部分,导致与氯贝特酸的强酸碱相互作用,但带隙的减少限制了光催化活性期间ROS的产生。
    Although a series of past studies proved the potential usage of Fe-based metal-organic frameworks (MOFs) as photocatalysts, there remains a knowledge gap of the photocatalytic mechanism stemming from the challenge to separate the simultaneous sorption and photocatalytic degradation. Thus, this article aimed to suggest a novel approach by desorbing target molecules during photocatalysis to excavate the underlying mechanisms of sorption and photocatalytic degradation. In this study, two Fe-based MOFs, MIL-101(Fe) and MIL-101(Fe)-NH2, were selected to remove clofibric acid under visible light irradiation. Prior to photocatalysis, sorption mechanism was uncovered based on the sorption kinetic, isotherm, thermodynamic interpretation, and of its dependence on solution pH. The results inferred that the primary sorption mechanism was through the π-π interaction between the benzene ring of clofibric acid and the organic ligand of Fe-based MOFs. Based on these results, photocatalytic mechanism could be independently or jointly assessed during the photocatalytic degradation of clofibric acid. Subsequently, the application of the Tauc method and XPS spectra revealed that the bandgap structure of Fe-based MOFs had the potential to oxidize clofibric acid by producing ROS through the electron excitation upon visible-light illumination. On top of that, the amine functionalization of Fe-based MOF altered the structural moiety that led to an additional strong acid-base interaction with clofibric acid but a decrease in the bandgap limiting the ROS production during photocatalytic activity.
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  • 文章类型: Journal Article
    耐药细菌感染对公众生活造成重大危害,健康,和财产。生物膜的特征是谷胱甘肽(GSH)的过表达,缺氧,和轻微的酸度,是形成细菌耐药性的主要因素之一。传统的抗生素治疗逐渐失去对多重耐药(MDR)细菌的功效。因此,协同治疗,调节生物膜微环境,是一个很有前途的策略。多功能纳米平台,SnFe2O4-PBA/Ce6@ZIF-8(SBC@ZIF-8),其中铁酸锡(SnFe2O4,表示为SFO)作为核心,负载3-氨基苯硼酸(PBA)和二氢卟啉e6(Ce6),最后用沸石咪唑盐骨架8(ZIF-8)涂覆。该平台具有协同光热疗法(PTT)/光动力疗法(PDT)的作用,可以通过谷胱甘肽过氧化物酶样活性有效去除过表达的GSH,降低生物膜的抗氧化能力,并增强PDT。该平台具有优异的光热性能(光热转换效率为55.7%)和光热稳定性。两种MDR菌的抑菌率均在96%以上,生物膜清除率达90%以上(150μg/mL)。在MDR金黄色葡萄球菌感染伤口的动物模型中,100μLSBC@ZIF-8+NIR(150μg/mL)处理后,小鼠的伤口面积减少了95%,几乎愈合。血清生化指标及H&E染色结果均在正常范围内,说明该平台能促进创面愈合,具有良好的生物安全性。在这项研究中,我们设计并合成了具有良好抗耐药细菌作用的多功能纳米平台,并阐明了其抗耐药细菌的分子机制。为临床应用于治疗创面感染和促进创面愈合奠定了基础。
    Drug-resistant bacterial infections cause significant harm to public life, health, and property. Biofilm is characterized by overexpression of glutathione (GSH), hypoxia, and slight acidity, which is one of the main factors for the formation of bacterial resistance. Traditional antibiotic therapy gradually loses its efficacy against multi-drug-resistant (MDR) bacteria. Therefore, synergistic therapy, which regulates the biofilm microenvironment, is a promising strategy. A multifunctional nanoplatform, SnFe2O4-PBA/Ce6@ZIF-8 (SBC@ZIF-8), in which tin ferrite (SnFe2O4, denoted as SFO) as the core, loaded with 3-aminobenzeneboronic acid (PBA) and dihydroporphyrin e6 (Ce6), and finally coated with zeolite imidazole salt skeleton 8 (ZIF-8). The platform has a synergistic photothermal therapy (PTT)/photodynamic therapy (PDT) effect, which can effectively remove overexpressed GSH by glutathione peroxidase-like activity, reduce the antioxidant capacity of biofilm, and enhance PDT. The platform had excellent photothermal performance (photothermal conversion efficiency was 55.7 %) and photothermal stability. The inhibition rate of two MDR bacteria was more than 96 %, and the biofilm clearance rate was more than 90 % (150 μg/mL). In the animal model of MDR S. aureus infected wound, after 100 μL SBC@ZIF-8+NIR (150 μg/mL) treatment, the wound area of mice was reduced by 95 % and nearly healed. The serum biochemical indexes and H&E staining results were within the normal range, indicating that the platform could promote wound healing and had good biosafety. In this study, we designed and synthesized multifunctional nanoplatforms with good anti-drug-resistant bacteria effect and elucidated the molecular mechanism of its anti-drug-resistant bacteria. It lays a foundation for clinical application in treating wound infection and promoting wound healing.
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  • 文章类型: English Abstract
    Objective: This study aimed to develop a new delivery strategy that utilized metal organic framework (MOF) loaded with small-interfering RNA (siRNA) targeting ITGAV to overcome tumor matrix barrier, and thus enhance drug penetration and immune accessibility in breast cancer. Methods: MOF@siITGAV particles were constructed and characterized. The uptake of MOF@siITGAV in breast cancer cell line 4T1 was observed by the cellular uptake assay. The toxicity of MOF@siITGAV was detected by cell counting kit 8 (CCK-8). The blank control group, naked siITGAV group and MOF@siITGAV group were set. Real-time fluorescent quantitative polymerase chain reaction (RT-qPCR) and Western blot were used to detect the expressions of ITGAV. The level of transforming growth factor β1 (TGF-β1) in the cell culture medium was detected by enzyme-linked immunosorbent assay (ELISA). The penetration of MOF@siITGAV in 4T1 cells was tested by constructing 3D spheroids. Mouse models of triple negative breast cancer were established. The effect of MOF@siITGAV on the growth of transplanted tumors and main organs was verified. Imminohistochemical (IHC) was used to test the expression of collagen and CD8. Results: MOF@siITGAV particles were constructed with sizes of (198.0±3.3) nm and zeta potential of -(20.2±0.4) mV. MOF@siITGAV could be engulfed by 4T1 cells and triggered to release siRNA. Compared to the blank control group, the expression of ITGAV in the MOF@siITGAV group [(46.5±11.3)%] and the naked siITGAV group [(109.9±19.0)%] was lower. TGF-β1 in the cell culture medium of the blank control group, naked siITGAV group, and MOF@siITGAV group was (474.5±34.4) pg/ml, (437.2±16.5) pg/ml, and (388.4±14.4) pg/ml, respectively. MOF@siITGAV could better penetrate into 4T1 spheroids and exhibit no obvious toxicity. The cell viability was (99.7±3.5)%, (98.2±5.2)%, (97.3±6.6)%, (92.1±8.1)%, and (92.4±4.1)%, respectively, after MOF@siITGAV treatment with the concentration of 0, 10, 20, 40, 80, and 160 μg/ml, respectively, for 24 h. The tumor growth in the MOF@siITGAV group was suppressed significantly. After 15-day treatment, the tumor volume of the MOF@siITGAV group was (135.3±41.9) mm3, smaller than that of the blank control group [(691.1±193.0) mm3] (P=0.025). The expression of collagen and the number of CD8 positive cells of the MOF@siITGAV group were lower than those of the other two groups. No significant abnormalities were observed in the main organs of mice. Conclusions: Targeting the integrinαv on the surface of cancer cells could destroy extracellular matrix, improve drug delivery, and increase immune infiltration.
    目的: 开发一种新型递送策略,利用金属有机框架(MOF)负载针对整合素αv(ITGAV)的小干扰RNA siITGAV,以克服基质屏障,进而增强乳腺癌内药物递送及免疫可及性。 方法: 构建MOF@siITGAV颗粒,对其进行材料表征。通过细胞摄取实验观察乳腺癌4T1细胞对MOF@siITGAV的摄取情况,细胞计数试剂盒8法检测MOF@siITGAV的细胞毒性。设空白对照组、游离siITGAV组和MOF@siITGAV组,采用实时荧光定量聚合酶链反应检测各组4T1细胞中ITGAV mRNA的表达,采用Western blot检测ITGAV蛋白的表达,采用酶联免疫吸附试验检测TGF-β1的含量。采用3D球体穿透实验观察MOF@siITGAV穿透4T1细胞球的能力。建立三阴性乳腺癌小鼠模型,观察MOF@siITGAV对移植瘤生长及小鼠心、肝、脾、肺、肾等主要脏器的影响,采用免疫组化染色检测肿瘤组织中Ⅰ型胶原蛋白和CD8的表达。 结果: 成功构建MOF@siITGAV颗粒,粒径为(198.0±3.3)nm,电位为-(20.2±0.4)mV。4T1细胞能有效摄取MOF@siITGAV,并触发siRNA的有效释放,MOF@siITGAV组细胞中ITGAV mRNA和蛋白表达水平、TGF-β1的表达水平均显著下调[相对于空白对照组,游离siITGAV组和MOF@siITGAV组4T1细胞中ITGAV mRNA相对表达水平分别为(109.9±19.0)%和(46.5±11.3)%;空白对照组、MOF@siNC组和MOF@siITGAV组TGF-β1浓度分别为(474.5±34.4)pg/ml、(437.2±16.5)pg/ml和(388.4±14.4)pg/ml]。MOF@siITGAV在4T1细胞球中的穿透能力更强,对4T1细胞无明显杀伤效应,0、10、20、40、80和160 μg/ml MOF@siITGAV分别处理4T1细胞24 h,细胞活性分别为(99.7±3.5)%、(98.2±5.2)%、(97.3±6.6)%、(92.1±8.1)%和(92.4±4.1)%。MOF@siITGAV能有效抑制小鼠乳腺癌移植瘤的生长,给药15 d后,空白对照组、MOF@siNC组和MOF@siITGAV组小鼠的肿瘤体积分别为(691.1±193.0)mm3、(652.7±306.5)mm3和(135.3±41.9)mm3,MOF@siITGAV组小鼠的肿瘤体积小于空白对照组(P=0.025)。与空白对照组和MOF@siNC组相比,MOF@siITGAV组小鼠肿瘤组织中Ⅰ型胶原蛋白的含量明显减少,CD8阳性细胞明显增多,心、肝、脾、肺、肾等主要脏器未见明显异常。 结论: ITGAV可以破坏乳腺癌的ECM,改善药物瘤内递送,促进免疫细胞浸润。.
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  • 文章类型: Journal Article
    将CO2催化转化为增值化工产品可以为环境问题的提出提供合适的解决方案。迄今为止,已经探索了具有过渡金属离子的各种金属有机骨架(MOFs)用于CO2捕获和转化,但碱土金属基MOFs的研究相对较少。具有相对大半径的金属离子如Sr(II)产生高配位数,导致MOF的更高稳定性。此外,在有机接头如-NH2、-CONH-和三唑中引入富含N的官能团到MOF主链中增强了它们的CO2捕获和转化效率。在这里,提出了在无溶剂和环境条件下,胺基对MOFs与环氧化物进行CO2环加成的催化效率的影响。二羧酸盐,例如5-氨基间苯二甲酸酯(AmIP)和5-溴间苯二甲酸酯(BrIP)用于合成基于Sr(II)的MOF。使用含有酰胺间隔基(OAT)和4-氨基-4H-1,2,4-三唑(AMT)的四羧酸酯合成Zn(II)MOF。所有三个MOF均表现出多孔网络,客人可用体积范围为15%至58%。探索了MOFs对二氧化碳固定反应的催化效率。催化性能表明,通道中胺基的存在增强了MOF的催化效率。
    Catalytic transformation of CO2 into value-added chemical products can provide an appropriate solution for the raising environmental issues. To date, various metal-organic frameworks (MOFs) with transition metal ions have been explored for CO2 capture and conversion, but alkaline earth metal-based MOFs are comparatively less studied. Metal ions like Sr(II) having relatively large radius give rise to a high coordination number resulting in higher stability of the MOFs. Moreover, the introduction of N-rich functional group in organic linker like -NH2, -CONH- and triazole into MOF backbone enhance their CO2 capture and conversion efficiency. Herein, the effect of amine group on the catalytic efficiency of MOFs for CO2 cycloaddition with epoxides under solvent free and ambient conditions are presented. The di-carboxylates, such as 5-aminoisophthalate (AmIP) and 5-bromoisophthalate (BrIP) were utilized to synthesize Sr(II) based MOFs. The Zn(II) MOF was synthesized using tetra-carboxylate containing amide spacer (OAT) and 4-amino-4H-1,2,4-triazole (AMT). All three MOFs exhibited porous networks with guest available volume ranging from 15 to 58 %. The catalytic efficiency of the MOFs towards carbon dioxide fixation reaction was explored. The catalytic performances revealed that the presence of amine group in the channels enhances the catalytic efficiency of the MOFs.
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  • 文章类型: Journal Article
    将酶包封在金属-有机骨架中是提高酶在苛刻条件下的稳定性的常见做法。然而,酶@MOFs的合成主要限于小规模的实验室环境,阻碍他们的工业应用。喷雾干燥是一种可扩展且具有成本效益的技术,在工业中经常用于大规模生产。尽管有这些优势,它在MOFs中包封酶的潜力仍未被开发,由于MOF颗粒形成导致喷嘴堵塞等挑战,利用有毒有机溶剂,被包封的酶的控释,和可能损害酶活性的高温。在这里,我们提出了一种使用无溶剂喷雾干燥制备植酸酶@MIL-88A的新方法。这涉及使用三流体喷嘴分别雾化两种MOF前体溶液,通过操纵MOF内的缺陷来控制酶的释放。使用X射线衍射表征喷雾干燥颗粒的物理化学性质,傅里叶变换红外光谱,和扫描电子显微镜。利用喷雾干燥在工业生产中的效率和可扩展性,这种可扩展的封装技术在广泛的工业应用中具有相当大的前景。
    Encapsulating enzymes in metal-organic frameworks is a common practice to improve enzyme stability against harsh conditions. However, the synthesis of enzyme@MOFs has been primarily limited to small-scale laboratory settings, hampering their industrial applications. Spray drying is a scalable and cost-effective technology, which has been frequently used in industry for large-scale productions. Despite these advantages, its potential for encapsulating enzymes in MOFs remains largely unexplored, due to challenges such as nozzle clogging from MOF particle formation, utilization of toxic organic solvents, controlled release of encapsulated enzymes, and high temperatures that could compromise enzyme activity. Herein, we present a novel approach for preparing phytase@MIL-88 A using solvent-free spray drying. This involves atomizing two MOF precursor solutions separately using a three-fluid nozzle, with enzyme release controlled by manipulating defects within the MOFs. The physicochemical properties of the spray dried particles are characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy. Leveraging the efficiency and scalability of spray drying in industrial production, this scalable encapsulation technique holds considerable promise for broad industrial applications.
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  • 文章类型: Journal Article
    将药物活性药物排放到水和废水中已成为重大的环境威胁。传统方法无法有效去除废水中的这些化合物,因此有必要寻找更有效的方法。这项研究调查了MIL-101(Cr)-NH2作为从水溶液中吸附和去除药物活性化合物的优选且更有效的吸附剂的潜力。通过利用它的大孔隙度,高比表面积,和高稳定性,三种药物活性化合物萘普生(NAP)的结构和转运特性,双氯芬酸(DIC)和磺胺甲恶唑(SMX)的分子动力学模拟研究。结果表明,MIL-101(Cr)-NH2吸附剂适用于去除水溶液中的药物分子,萘普生的最大吸附容量为697.75mg/g,704.99mg/g双氯芬酸,磺胺甲恶唑为725.51mg/g。
    Discharging pharmaceutically active drugs into water and wastewater has become a significant environmental threat. Traditional methods are unable to effectively remove these compounds from wastewater, so it is necessary to search for more effective methods. This study investigates the potential of MIL-101(Cr)-NH2 as a preferable and more effective adsorbent for the adsorption and removal of pharmaceutically active compounds from aqueous solutions. By utilizing its large porosity, high specific surface area, and high stability, the structural and transport properties of three pharmaceutically active compounds naproxen (NAP), diclofenac (DIC) and sulfamethoxazole (SMX)) studied using molecular dynamics simulation. The results indicate that the MIL-101(Cr)-NH2 adsorbent is suitable for removing drug molecules from aqueous solutions, with maximum adsorption capacities of 697.75 mg/g for naproxen, 704.99 mg/g for diclofenac, and 725.51 mg/g for sulfamethoxazole.
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  • 文章类型: Journal Article
    金属有机骨架(MOF)孔中吸附的客体物种的定量测量对于评估MOF的吸附性能至关重要。然而,常规分析技术,如热重分析不能区分孔中吸附的物质的贡献,吸附在表面上的物种,以及包封在晶间空间中的气相或液相。在这里,我们开发了一种基于交叉极化(CP)固态核磁共振(SSNMR)技术的新定量方法,其中只有MOF孔内的物质被选择性探测,因为迁移率显著降低。以商业化的MOFα-Mg3(HCOO)6为例,Areaguest/Areafrone之间的良好线性相关性(即,客体和框架13C核磁共振信号的综合区域,分别)和客体负载可以观察到几个代表性分子,如苯,四氢呋喃(THF),和1,4-二恶烷,清楚地揭示了CP量化方法的可行性。通过改变客体分子的几何形状和大小,进一步讨论了客体分子和相应的残留迁移率对CP定量的影响。该方法为深入评价多孔材料的吸附性能提供了一条有效且不可替代的途径,特别是液相吸附和气相吸附,其中毛细管冷凝是不可忽略的。
    The quantitative measurement of adsorbed guest species within metal-organic framework (MOF) pores is of fundamental importance for evaluating the adsorption performance of MOFs. However, routine analytic techniques such as thermogravimetric analysis cannot distinguish the contribution from species adsorbed within pores, species adsorbed on the surface, and gas phase or liquid phase encapsulated in the inter-crystalline space. Herein, we developed a new quantification method based on the cross-polarization (CP) solid-state nuclear magnetic resonance (ssNMR) technique, in which only the species within MOF pores are selectively probed due to the dramatically reduced mobility. Using the commercialized MOF α-Mg3(HCOO)6 as an example, a good linear correlation between Areaguest/Areaframework (i. e., the integrated area of guest and framework 13C NMR signals) and guest loading can be observed for several representative molecules such as benzene, tetrahydrofuran (THF), and 1,4-dioxane, clearly revealing the feasibility of CP quantification approach. The effects of guest molecule and corresponding residual mobility on the CP quantification are further discussed by varying the geometry and size of guest molecules. This methodology thus provides an effective and irreplaceable route to evaluate the adsorption performance of porous materials in-depth, especially for liquid-phase adsorption and gas-phase adsorption in which the capillary condensation is not negligible.
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  • 文章类型: Journal Article
    在目前的调查中,MnFe2O4/ZIF-8纳米复合材料作为磁性纳米吸附剂,使用龙舌兰植物的提取物和XRD表征,FTIR,VSM,BET,FESEM,EDS映射,TEM,XPS,TPD-NH3和TGA分析。此外,为了确定其在四环素吸附过程中的效率,pH(3-9)的影响,纳米复合材料剂量(0.025-2g/L),初始污染物浓度(5-100mg/L),接触时间(5-200分钟),和温度(5-50°C)进行了研究。磁性纳米复合材料的形态特性的结果证实了该纳米吸附器的球形,平均尺寸为54±31nm。BET分析表明,用ZIF-8作为新型纳米吸附剂对MnFe2O4材料进行改性可对SBET(143.8m2/g)和VTotal(0.44cm3/g)进行出色的改性。在最佳条件下(pH=7,接触时间=120min,纳米复合材料剂量=1.5g/L,对于浓度为20mg/L的四环素,温度=20°C)为90.11%。随着温度的升高,在120分钟内,去除效率从40.46%提高到95.06%,这表明吸附反应是吸热的。此外,从朗缪尔等温线获得的数据(R2=0.958),Freundlich(R2=0.534),和Temkin(R2=0.747)表明,四环素吸附是单层的,并且在合成的磁性纳米吸附剂的均匀表面上。纳米吸附器对四环素的消除过程遵循伪二阶模型(R2=0.998)。研究干扰离子的影响也证实了吸附效率的降低。此外,对合成的磁性纳米吸附剂在四环素吸附中的可重用性的研究表明,经过八个循环,效率下降16.51%。根据结果,在这项工作中合成的磁性纳米复合材料可以是从水性环境中去除四环素的合适且经济的吸附剂。
    In the current investigation, MnFe2O4/ZIF-8 nanocomposite was generated as a magnetic nanoadsorber using the extract of Dracocephalum plant and characterized by XRD, FTIR, VSM, BET, FESEM, EDS-mapping, TEM, XPS, TPD-NH3, and TGA analyses. Also, to determine its efficiency in the adsorption process of tetracycline, the effect of pH (3-9), nanocomposite dose (0.025-2 g/L), initial pollutant concentration (5-100 mg/L), contact time (5-200 min), and temperature (5-50 °C) were studied. The results of the morphological properties of the magnetic nanocomposite confirmed the spherical shape of this nanoadsorber with an average size of 54 ± 31 nm. BET analysis showed that modification of MnFe2O4 material with ZIF-8 as a new nanoadsorber leads to excellent modification of SBET (143.8 m2/g) and VTotal (0.44 cm3/g). The highest removal efficiency of tetracycline in optimal conditions (pH = 7, contact time = 120 min, nanocomposite dose = 1.5 g/L, and temperature = 20 °C for a tetracycline concentration of 20 mg/L) was 90.11%. As the temperature increased, the removal efficiency increased from 40.46% to 95.06% during 120 min, which indicates that the adsorption reaction is endothermic. In addition, the data obtained from the isotherms of Langmuir (R2 = 0.958), Freundlich (R2 = 0.534), and Temkin (R2 = 0.747) showed that the tetracycline adsorption is monolayer and on the homogeneous surface of the synthesized magnetic nanoadsorber. The elimination process of tetracycline by nanoadsorber followed the pseudo-second order model (R2 = 0.998). Investigating the effect of interfering ions also confirmed the decrease in the adsorption efficiency. Also, the investigation of the reusability of the synthesized magnetic nanoadsorber in tetracycline adsorption indicates that after eight cycles, the efficiency decreases by %16.51. According to the results, the magnetic nanocomposite synthesized in this work can be a suitable and economical adsorber for the removal of tetracycline from aqueous environments.
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