• Applied Chemistry for Engineering
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• v.34 no.5
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• pp.556-565
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• 2023

Fast industrial and agricultural expansion result in the production of heavy metal ions (HMIs). These are exceedingly hazardous to both humans and the environment, and the necessity to eliminate them from aqueous systems prompts the development of novel materials. In the present study, a UIO-66 (COOH)₂ metal-organic framework (MOF) containing free carboxylic acid groups was post-synthetically modified with L-glutamic acid via the solid-solid reaction route. Pristine and glutamic acid-treated MOF materials were characterized in detail using several physicochemical techniques. Single-ion batch adsorption studies of Pb(II) and Hg(II) ions were carried out using pristine as well as amino acid-modified MOFs. We further examined parameters that influence removal efficiency, such as the initial concentration and contact time. The bare MOF had a higher ion adsorption capacity for Pb(II) (261.87 mg/g) than for Hg(II) ions (10.54 mg/g) at an initial concentration of 150 ppm. In contrast, an increased Hg(II) ion adsorption capacity was observed for the glutamic acid-modified MOF (80.6 mg/g) as compared to the bare MOF. The Hg(II) ion adsorption capacity increased by almost 87% after modification with glutamic acid. Fitting results of isotherm and kinetic data models indicated that the adsorption of Pb(II) on both pristine and glutamic acid-modified MOFs was due to surface complexation of Pb(II) ions with available -COOH groups (pyromellitic acid). Adsorption of Hg(II) on the glutamic acid-modified MOF was attributed to chelation, in which glutamic acid grafted onto the surface of the MOF formed chelates with Hg(II) ions.

• Applied Chemistry for Engineering
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• v.31 no.6
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• pp.591-595
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• 2020

Intensive pulsed light (IPL) technique enables energy to be transferred to a target substance in a short time per millisecond at room temperature under an ambient atmosphere. Due to the growing interest in flashlights with excellent functionality among various technologies, light-sintering research on metal particles using IPL has been carried out representatively. Recently, examples of the application of IPL to various material synthesis have been reported. In the present article, various strategies using IPL including the manufacture of flexible electrodes and the synthesis of metal-organic frameworks were discussed. In particular, the process of improving oxidation resistance and electrical conductivity of electrodes, and also the metal-organic framework synthesis from metal surface were explained in detail. We envision that the review article can be of great help to researchers who investigate electrode manufacturing and material synthesis using IPL.

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2705-2710
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• 2011

Four MOFs functionalized with 1-Me, 1-Pr, 1-Ph, and 1-$PhCF_3$ were prepared through post-synthetic modifications of a metal-organic framework (MOF), UMCM-1-$NH_2$ (1) with acetic, butyric, benzoic, and 4-(trifluoromethyl)benzoic anhydrides, respectively. Methane adsorption measurements between 253 and 298 K at pressures up to 1 bar indicated that both 1-Ph and 1-$PhCF_3$ adsorbed more $CH_4$ than the parent MOF, 1. All the functionalized MOFs adsorbed more $CO_2$ than 1 under conditions similar to the $CH_4$ test. The introduction of functional groups promoted adsorption of both $CH_4$ and $CO_2$ despite significantly reducing Brunauer-Emmet-Teller (BET) surface area: 4170 (1), 3550 (1-Me), 2900 (1-Pr), 3680 (1-Ph), and 3520 $m^2/g$ (1-$PhCF_3$). Electron-withdrawing aromatic groups (1-Ph, 1-$PhCF_3$) more effectively enhanced $CO_2$ adsorption than electron-donating alkyl groups (1-Me, 1-Pr). In particular, 1-Ph adsorbed 23% more $CO_2$ at 298 K and 50% more at 253 K than 1.

• Clean Technology
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• v.19 no.4
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• pp.370-378
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• 2013

This review has shown the capability of MOFs and ZIFs materials to adsorb $CO_2$ under typical PSA temperatures and pressures. The usual operating conditions are adsorption temperatures of $15{\sim}40^{\circ}C$ and adsorption pressures of 4~6 bar based on numerous PSA processes which are widely employed in gases industry for adsorptive separation of $CO_2$. The extent of $CO_2$ adsorption on the microporous materials depends on the metal species and organic linkers existing in the frameworks. The pore size and the surface area, and the process variables are the key parameters to be associated with the efficiency of the adsorbents, particularly adsorption pressures if other variables are comparable each other. The MOFs and ZIFs materials require high pressures greater than 15 bar to yield significant $CO_2$ uptakes. They possess a $CO_2$ adsorption capacity which is very similar to or less than that of conventional benchmark adsorbents such as zeolites and activated carbons. Consequently, those materials have been much less cost-effective for adsorptive $CO_2$ separation to date because of very high production price and the absence of commercially-proven PSA processes using such new adsorbents.

• Journal of Surface Science and Engineering
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• v.51 no.1
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• pp.21-26
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• 2018

The $Cu_2(btc)_3$ metal-organic frameworks (MOF) coated anodic aluminum oxide (AAO) membrane was successfully prepared by layer-by-layer technique using hand spray method. It was confirmed that the $Cu_2(btc)_3$ layer, which has the pore sized in 2-3 nm, on surface of AAO exhibited the polycrystalline thin film structure by XRD analysis. More than 100 repetitive spray cycles were required to obtain more robust and thick MOFs on AAO and it was possible to uniformly coat both the top and bottom surfaces of the AAO. It should be noted that the MOFs also could be coated on surface of pores resulting in reduce the size of pore from 52 nm to 32 nm.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2477-2480
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• 2014

Thermal degradation of titanium-containing metal-organic frameworks (MOFs; MIL-125 and MIL-125-$NH_2$ at $350^{\circ}C$ for 6 h in air produced $TiO_2$ nanoparticles of ca. 10 nm in diameter. Scanning electron and transmission electron microscope analyses indicated that those nanoparticles were aggregated randomly within each crystalline particle of their MOF precursors. The $TiO_2$ nanoparticles prepared from MIL-125-$NH_2$ exhibited higher activity for the degradation of 4-chlorophenol under visible light.

• Journal of the Korean Ceramic Society
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• v.53 no.2
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• pp.200-205
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• 2016

With high specific surface area and pore structural diversity, MOFs show important applications in gas storage, catalysis, sensing, separation, and biomedicine. However, the stability of the structure of MOFs has restricted their application and development. In this study, zirconium metal organic frameworks with 9,10-dicarboxylic acid anthracene as ligand, named UIO-66 ($H_2DCA$), were synthesized and their properties and structures were characterized by XRD, SEM, and $N_2$ adsorption. We focus on the stability of the structure of UIO-66 ($H_2DCA$) under different conditions (acid, alkali, and water). The structural changes or ruins of UIO-66 ($H_2DCA$) were traced by means of XRD, TG, and FT-IR under different conditions. The results show that the UIO-66 ($H_2DCA$) materials are stable at 583 K, and that this structural stability is greatly influenced by different types of acid and alkali compounds. Importantly, we found that the structures maintain their stability in environments of nitric acid, triethylamine, and boiling water.

• Clean Technology
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• v.20 no.2
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• pp.116-122
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• 2014

Various types of MOFs (metal-organic frameworks) were prepared via hydrothermal and post-grafting methods and applied as catalysts for the synthesis of jasminaldehyde, one of the representative perfume intermediates, by Aldol condensation of benzaldehyde with heptanal. Although both acid and base sites could catalyze the reaction, the catalytic performance was strongly dependent on the physical properties as well as the nature of functionalization on MOFs. While the use of sulfonated MOF catalysts led to decrease of jasminaldehyde selectivity regardless of MOFs used, the selectivity change was found to rely on the MOF types in the case of the amine-functionalization. Among the catalysts tested, MIL-101 shows the best catalytic performance, which may suggest that MIL-101 has suitable acid properties to promote the Aldol condensation and the large pore of MIL-101 is also advantageous to alleviate the diffusion problem of bulky products.

• Korean Chemical Engineering Research
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• v.61 no.1
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• pp.1-7
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• 2023

Gas separation technology becomes more useful because key gases such as H₂ and CO₂ regarding renewable energy resources and environmental pollutant can be effectively extracted in mixed gases. For reducing energy consumption on gas separation, membrane and adsorption processes are widely used. In both processes, porous materials are needed as membrane and adsorbent. In particular, metal-organic frameworks (MOFs), one class of the porous materials, have been developed for the purpose of gas adsorption and separation. While the number of the MOF structures is increasing due to chemical and structural tunability, good MOF membranes and adsorbents have been rarely reported by trial-and-error experiments. To accelerate the discovery of high-performing porous materials that can separate H₂ and CO₂, a high-throughput computational screening technique was used as efficient skill. This review introduces crucial studies of porous materials and the high-throughput computational screening works focusing on gas separation of H₂ and CO₂.

• Journal of Energy Engineering
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• v.24 no.2
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• pp.51-54
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• 2015

The mesoporous metal organic framework structure of Ni-BTC was successfully synthesized in a low temperature and short operation time via hydrothermal synthesis process. Such operational route virtuously consumed less electrical and thermal energy. It proved time saving along with acceptable product yield (38%). The product was characterized through FESEM, FT-IR, XRD and $N_2$ gas adsorption measurement. Hightemperature stability of synthesized MOF was gauged by diffraction indexing of XRD patterns of as synthesized and heat treated samples of MOFs. The mathematically calculated particle size of Ni-BTC was found to be 42nm.