Sharif Digital Repository

Two newly synthesised Schiff bases [H2A3, N,N′-ortho-phenylene(salicylaldimine-acetylacetone imine) and H2A4, N,N′-ortho-phenylene(salicylaldimine-2-hydroxy-1-naphthaldimine)] were studied as inhibitors for the corrosion of mild steel in 0.5 mol dm-3 sulphuric acid. Results of weight loss, electrochemical impedance and Tafel polarisation measurements consistently identify both compounds as good inhibitors, with efficiencies of around 95% at a concentration of 400 ppm. The inhibition is in both cases of a mixed anodic-cathodic nature. Differences in inhibition efficiency between H2A3 and H2A4 are correlated with their chemical structures. Several adsorption isotherms are assessed, and the... 

In the present work, adsorption of hydrogen molecules over a metal organic framework (MOF-5) has been investigated by using first principles density functional theory (DFT). Different strategies have been applied for improving hydrogen storage, i.e. metal doping, boron substitution and functionalization. The metal atoms used for enhancing hydrogen adsorption include Li, Ca and Sc. It is found that the binding energy between these metal atoms and MOF is not enough to prevent clustering. Therefore a number of carbon atoms are substituted by boron atoms and it is indicated that boron substitution enhances the binding energies, significantly. Also the results reveal that boron substituted MOF... 

Silver-based nanomaterials have attracted considerable attention due to their antimicrobial activities. In this work, a silver (Ag)-based metal organic framework (Ag-MOF) is embellished with graphene-oxide (GO), leading to the fabrication of a novel Ag-based nanocomposite (GO-Ag-MOF) whose biocidal activity is higher than those of Ag-MOF and GO nanomaterials. The nanocomposite is characterized using X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscope, Fourier transform infrared spectra, ultraviolet−visible absorption spectra, X-ray powder diffraction, dynamic light scattering, and nitrogen gas adsorption/desorption. The characterization shows that... 

The fluoride ion is usually added to drinking water because of its prominent role in treating osteoporosis and improving dental health. However, fluoride contents over the optimal level (>1.5 ppm) in water resources has been found to have harmful effects on human health such as bone and dental fluorosis, Alzheimer's syndrome, DNA damage, infertility, kidney failure, acute gastric problems, thyroid disorder, brain damage, and even cancer. Therefore, sensitive and selective detection of fluoride ions and their removal from drinking water are of great significance. The unique features of metal–organic frameworks (MOFs), such as chemical activities, a broad range of functionalities, high... 

The fluoride ion is usually added to drinking water because of its prominent role in treating osteoporosis and improving dental health. However, fluoride contents over the optimal level (>1.5 ppm) in water resources has been found to have harmful effects on human health such as bone and dental fluorosis, Alzheimer's syndrome, DNA damage, infertility, kidney failure, acute gastric problems, thyroid disorder, brain damage, and even cancer. Therefore, sensitive and selective detection of fluoride ions and their removal from drinking water are of great significance. The unique features of metal–organic frameworks (MOFs), such as chemical activities, a broad range of functionalities, high... 

A new magnetic composite was synthesized by integration of ZnFe2O4 and MIL-53(Fe) micro-rods by a solvothermal method. This composite served as a heterogeneous catalyst to overcome the high electron-hole recombination rates of ZnFe2O4 and to enhance the degradation of Direct Red 23 under visible light irradiation. Different analytical techniques, including XRD, FTIR, SEM, DRS, VSM, and PL, were employed to characterize the synthesized heterojunction nanocomposite and to evaluate its photocatalytic activity. The ZnFe2O4/MIL-53(Fe)/Vis-light system resulted in significantly higher dye degradation as compared with pristine ZnFe2O4 and MIL-53(Fe) semiconductors at the optimum pH of 3.1 and... 

The adsorptive removal of terephthalic acid (TPA) and p-toluic acid (p-tol) by metal organic frameworks (MOF) of Cu-BTC, Fe-BTC, MIL-101(Cr) and MIL-53(Al) was investigated in this study. The influence of various factors including solution pH, contact time, and initial concentration of TPA and p-tol solutions on the adsorption behavior was evaluated. Different adsorption isotherms and kinetic models were used to fit experimental adsorption data. It was found that the Langmuir and Redlich-Peterson adsorption isotherms were adequate to represent the experimental data (R2 > 0.97) and that the adsorption kinetics was well-represented by a pseudo-second-order kinetic model (R2 > 0.98). The zeta... 

A metal-organic framework [Co3(BDC)3(DMF)2(H2O)2] was synthesized and structurally characterized. X-ray single crystal analysis revealed that the framework contains a 2D polymeric chain through coordination of 1,4-benzenedicarboxylic acid linker ligand to cobalt centers. The polymer crystallize in monoclinic P21 /n space group with a=13.989(3) Å, b=9.6728(17) Å, c=16.707(3) Å, and Z=2. The polymer features a framework based on the perfect octahedral Co-O6 secondary building units. The catalytic activities of [Co3(BDC)3(DMF)2(H2O)2]n for olefins oxidation was conducted. The heterogeneous catalyst could be facilely separated from the reaction mixture, and reused three times without significant... 

We show that a metal-organic framework (MOF) sustained by a nanosized Ag12 cuboctahedral node can be applied to selectively extract traces of lead(II) ion from environmental water samples. The MOF was characterized by thermogravimetric and differential thermal analysis, scanning electron microscopy, FTIR, and X-ray diffraction. The effects of pH value, flow rates, of type, concentration and volume of the eluent, of break-through volume and potentially interfering ions on the separation and determination of lead were evaluated. Following desorption with EDTA, Pb(II) was quantified by FAAS. The use of the MOF results in excellent analytical figures of merit including an analytical range from 2... 

A three–dimensional metal organic framework (3D–MOF) and a two–dimensional polyoxometalate (2D–POM), both incorporating nanostructured molybdenum (VI) oxide, were synthesized and implemented for headspace needle trap extraction of traces of chlorobenzenes (CBs). The 3D–MOF of type {(Mo2O6)(4,4′–bpy)}n and the 2D–POM of type [4,4′–bpy][Mo7O22] were synthesized by a solvothermal process and characterized by FT–IR, powder X–ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetry, energy dispersive X–ray, elemental mapping and Brunner–Emmet–Teller adsorption analyses. The 3D–MOF proved to be superior. Following thermal desorption, the CBs... 

A metal organic framework (MOF) modified with amino group (NH2-UiO-66) was functionalized with glycidyl methacrylate (GMA) via ring opening reaction between the amine species in the framework and epoxy groups in GMA. The products were characterized by X-ray powder diffraction (XRD), nuclear magnetic resonance (NMR) spectroscopy, field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), inductively coupled plasma-optical emission spectrometry (ICP-OES), and N2 adsorption–desorption measurements to monitor their textural properties before and after functionalization. The BET surface area, pore volume, and pore... 

MIL-101(Cr) metal–organic framework samples were successfully synthesized through the conventional electrical heating (CE), ultrasound (US), and microwave (MW) synthetic methods at three different temperatures and various synthesis times. These were done with the aim of understudying the crystallization kinetics of these complex MIL's structures. The nucleation and crystal growth steps were thus, quantified through measuring the relative crystallinity of the prepared MIL-101(Cr) utilizing the PXRD and FESEM analysis under various synthesis conditions. In addition, the textural properties of the fully crystallized samples measured through the N2 adsorption–desorption isotherms at 77 K. The... 

Metal–organic frameworks (MOFs) are best known for their great structural diversity. The uniformity in the properties of MOFs is mainly governed by the size and morphology of the particles. In the present research, iron-MIL-88A was prepared by a modulator-assisted solvothermal method, and the role of modulating agents in the formation process of MOF particles was investigated. Acetic acid and formic acid were chosen as monoligand modulating agents. The changes in morphology and size distribution of the products were scrutinized by using SEM micrographs. Both modulators clearly interfered with the crystallization process through their attachment to the reactive sites. At low modulator... 

One of the appealing usages of metal–organic frameworks is their application in manufacturing of metal oxide and metal oxide nanocomposites. In the present study, we used zeolitic imidazolate framework (ZIF-8) as precursor to prepare a new Ag/C/ZnO catalyst. The as-prepared samples were characterized using X-ray diffraction, Fourier-transform infrared, scanning electron microscopy and transmission electron microscopy analysis. Improved catalytic performance of as-prepared Ag/C/ZnO was confirmed by reduction of organic pollutants including p-nitrophenol, methylene blue and rhodamine-B in the presence of NaBH 4 in aqueous media. The synergistic effect between Ag and ZnO was proposed as the... 

The nanocomposite of g-C 3 N 4 supported by MIL-88A has been prepared via a facile hydrothermal method. The photocatalytic performance of as-prepared composite (MIL-88A/g-C 3 N 4 ) was examined by the degradation of the Methylene Blue (MB) solution under visible light. The characterization test illustrated that the MIL-88A particles were successfully dispersed on the surface of g-C 3 N 4 structure. Photoactivity results demonstrated that the MIL-88A/g-C 3 N 4 /H 2 O 2 exhibited dramatically visible light photocatalytic performance. Hydroxyl radicals ([rad]OH) are generated by dissociation of H 2 O 2 under visible irradiation can remarkably enhance the degradation rate of MB molecules.... 

A highly efficient, cost-effective, and durable electrocatalysts based on CoNi metal–organic framework (MOF) nanosheets on highly porous conductive graphene (PCG) is introduced for the hydrogen evolution reaction (HER). The electrocatalyst was fabricated by template-assisted chemical vapor deposition of graphene followed by solvothermal growth of CoNi-MOF nanosheets. Highly porous 3D structure of PCG with open channels of 200–500 nm sizes provided high active surface area and facilitates gas evolution. In a highly alkaline solution, the electrocatalyst exhibits superior figures of merits, e.g. overpotential of 265 mV at −10 mA cm−2 and Tafel slope of 44.5 mV dec-1, to existing hydrogen... 

The nano metal-organic frameworks (NMOFs) have been developed for drug delivery systems due to their high porosity and large specific surface area. In this work, UiO-66-NH2 NMOFs were synthesized via the microwave heating method and doxorubicin (DOX) as an anticancer drug was incorporated into the UiO-66-NH2 NMOFs. Then, poly(N-vinylcaprolactam) (PNVCL) synthesized by the free radical polymerization was coated on the UiO-66-NH2 NMOFs surface to fabricate dual pH/temperature-responsive nanocomposite against A549 lung cancer cells death in vitro. The synthesized nanocarriers were characterized using FTIR, 1H NMR, DLS, XRD, SEM, FESEM, TGA, and BET analysis. The average particle sizes of... 

Metal Organic Frameworks (MOFs) have received enormous attention in catalysis field due to their special structures and various promising applications. One of the intriguing applications of MOFs is utilization of them as precursors for synthesis of metal oxide nanomaterials. Base on this strategy, in this work, we have applied Cu-MOF to prepare a series of noble metal nanoparticles (Ag and Au) decorated CuO (M/CuO) as efficient catalyst. As-prepared nanocomposites were characterized by various analytical techniques and their catalytic performances appraised by using of the catalytic reduction of p-nitrophenol to p-aminophenol as a reliable model reaction. Experimental results suggest that... 

Excess fluoride is one of the water pollutants in the world, which is removed from water by chemical methods to produce sludge. On the other hand, techniques such as R.O. (Reverse Osmosis) also have problems with power consumption and wastewater disposal. Metal-organic frameworks are one of the newest adsorbents used to separate anions. In this study, MOF1 ({[Zn3L3(BPE)1.5]·4.5DMF}n) was used to remove fluoride from the aqueous solution. The influence of various factors such as pH, contact time, adsorbent amount, and temperature on fluoride uptake was investigated. Based on the results, the MOF synthesized in acidic media absorbs more fluoride ions. The reaction time in the first 20 min had... 

In this study, first, the UiO-66-NH2 metal-organic frameworks (MOFs) were modified with graphene quantum dots (GQDs) to facilitate the water attraction on MOF surface as well as improve their compatibility/affinity with the polyamide layer matrix of forward osmosis (FO) membranes. Next, to fabricate a new type of thin-film nanocomposite (TFN) membranes, the synthesized GQDs@UiO-66-NH2 composites are incorporated into the polyamide (PA) selective layer of FO membranes during the interfacial polymerization reaction of m-phenylenediamine (MPD) and trimesoyl chloride (TMC). The influence of the prepared fillers on the chemical structure, morphology, surface roughness and hydrophilicity of the PA...