Sung Hwa Jhung

High Uptakes of CO2 and CH4 in Mesoporous Metal—Organic Frameworks MIL-100 and MIL-101

Mesoporous MOFs MIL-100 and MIL-101 adsorb huge amounts of CO2 and CH4. Characterization was performed using both manometry and gravimetry in different laboratories for isotherms coupled with microcalorimetry and FTIR to specify the gas-solid interactions. In particular, the uptake of carbon dioxide in MIL-101 has been shown to occur with a record capacity of 40 mmol g(-1) or 390 cm3STP cm(-3) at 5 MPa and 303 K.

Adsorptive removal of hazardous materials using metal-organic frameworks (MOFs): a review.

Efficient removal of hazardous materials from the environment has become an important issue from a biological and environmental standpoint. Adsorptive removal of toxic components from fuel, waste-water or air is one of the most attractive approaches for cleaning technologies. Recently, porous metal-organic framework (MOF) materials have been very promising in the adsorption/separation of various liquids and gases due to their unique characteristics. This review summarizes the recent literatures on the adsorptive removal of various hazardous compounds mainly from fuel, water, and air by virgin or modified MOF materials. Possible interactions between the adsorbates and active adsorption sites of the MOFs will be also discussed to understand the adsorption mechanism. Most of the observed results can be explained with the following mechanisms: (1) adsorption onto a coordinatively unsaturated site, (2) adsorption via acid-base interaction, (3) adsorption via π-complex formation, (4) adsorption via hydrogen bonding, (5) adsorption via electrostatic interaction, and (6) adsorption based on the breathing properties of some MOFs and so on.

Adsorptive removal of methyl orange and methylene blue from aqueous solution with a metal-organic framework material, iron terephthalate (MOF-235)

An iron terephthalate (MOF-235), one of the metal-organic frameworks (MOFs), has been used for the removal of harmful dyes (anionic dye methyl orange (MO) and cationic dye methylene blue (MB)) from contaminated water via adsorption. The adsorption capacities of MOF-235 are much higher than those of an activated carbon. The performance of MOF-235 having high adsorption capacity is remarkable because the MOF-235 does not adsorb nitrogen at liquid nitrogen temperature. Based on this study, MOFs, even if they do not adsorb gases, can be suggested as potential adsorbents to remove harmful materials in the liquid phase. Adsorption of MO and MB at various temperatures shows that the adsorption is a spontaneous and endothermic process and that the entropy increases (the driving force of the adsorption) with adsorption of MO and MB.

Removal of hazardous organics from water using metal-organic frameworks (MOFs): Plausible mechanisms for selective adsorptions

Provision of clean water is one of the most important issues worldwide because of continuing economic development and the steady increase in the global population. However, clean water resources are decreasing everyday, because of contamination with various pollutants including organic chemicals. Pharmaceutical and personal care products, herbicides/pesticides, dyes, phenolics, and aromatics (from sources such as spilled oil) are typical organics that should be removed from water. Because of their huge porosities, designable pore structures, and facile modification, metal-organic frameworks (MOFs) are used in various adsorption, separation, storage, and delivery applications. In this review, the adsorptive purifications of contaminated water with MOFs are discussed, in order to understand possible applications of MOFs in clean water provision. More importantly, plausible adsorption or interaction mechanisms and selective adsorptions are summarized. The mechanisms of interactions such as electrostatic interaction, acid-base interaction, hydrogen bonding, π-π stacking/interaction, and hydrophobic interaction are discussed for the selective adsorption of organics over MOFs. The adsorption mechanisms will be very helpful not only for understanding adsorptions but also for applications of adsorptions in selective removal, storage, delivery and so on.

Adsorptive removal of naproxen and clofibric acid from water using metal-organic frameworks.

Adsorptive removal of naproxen and clofibric acid, two typical PPCPs (pharmaceuticals and personal care products), has been studied using metal-organic frameworks (MOFs) for the first time. The removal efficiency decreases in the order of MIL-101>MIL-100-Fe>activated carbon both in adsorption rate and adsorption capacity. The adsorption kinetics and capacity of PPCPs generally depend on the average pore size and surface area (or pore volume), respectively, of the adsorbents. The adsorption mechanism may be explained with a simple electrostatic interaction between PPCPs and the adsorbent. Finally, it can be suggested that MOFs having high porosity and large pore size can be potential adsorbents to remove harmful PPCPs in contaminated water.

Synthesis of a metal-organic framework material, iron terephthalate, by ultrasound, microwave, and conventional electric heating: a kinetic study.

A metal-organic framework material named MIL-53(Fe), iron terephthalate, has been synthesized sovothermally at a relatively low temperature by not only conventional electric (CE) heating, but also by irradiation under ultrasound (US) and microwave (MW) conditions to gain an understanding of the accelerated syntheses induced by US and MW. The kinetics for nucleation and crystal growth were analyzed by measuring the crystallinity of MIL-53(Fe) under various conditions. The nucleation and crystal growth rates were estimated from crystallization curves of the change in crystallinity with reaction time. The activation energies and pre-exponential factors were calculated from Arrhenius plots. It was confirmed that the rate of crystallization (both nucleation and crystal growth) decreases in the order US>MW>>CE, and that the accelerated syntheses under US and MW conditions are due to increased pre-exponential factors rather than decreased activation energies. It is suggested that physical effects such as hot spots are more important than chemical effects in the accelerated syntheses induced by US and MW irradiation. The syntheses were also conducted in two steps to understand quantitatively the acceleration induced by MW and it was found that the acceleration in crystal growth is more important than the acceleration in nucleation, even though both processes are accelerated by MW irradiation.

Selective formation of SAPO-5 and SAPO-34 molecular sieves with microwave irradiation and hydrothermal heating

Abstract SAPO-5 and SAPO-34 molecular sieves can be selectively formed with microwave irradiation and hydrothermal heating, respectively, of the same gel irrespective of the acidity or the type of the templates such as triethylamine and N,N,N′,N′-tetraethylethylenediamine. The SAPO-5 structure may transform into the SAPO-34 structure with increase of crystallization time probably due to the relative stability of the two phases at the reaction conditions. Crystallization with microwave irradiation can be used as a phase selective synthesis method for unstable material because of fast crystallization.

Remarkable Adsorption Capacity of CuCl2‐Loaded Porous Vanadium Benzenedicarboxylate for Benzothiophene

There is a considerable demand to reduce the content of sulfur-containing compounds (S-compounds) such as thiophene (Th), benzothiophene (BT), and dimethyldibenzothiophene (DMDBT) in fuels like diesel and gasoline to a low level to prevent air pollution and deactivation of catalysts. So far, various methods have been investigated for sulfur removal, and adsorption has been regarded as one of the most competitive methods. For efficient adsorption, not only adequate porosity/pore size but also specific adsorption sites are required. Remarkable progress on porous materials has been achieved because of the developments of metal–organic framework materials (MOFs) and coordination polymers (CPs). The importance of MOF-type materials is due to the huge porosity, easy tunability of their pore size and shape, and potential applications. Recently, the MOF-type materials have also been investigated for the removal of harmful materials such as S-compounds, 2] dyes, N-containing compounds, and benzene from liquids. Gaseous sulfur compounds have also been removed using MOFs. 11] A few important factors, such as open metal sites, acid sites, and pore functionality have been suggested for the efficient removal of S-compounds. However, little has been understood for the high uptake of S-compounds with modified MOFs as adsorbents. Herein, we have shown the remarkable adsorption capacity for BT over a modified MOF, CuCl2-loaded MIL47 (MIL = materials of the Institute Lavoisier). MIL-47 is a typical MOF composed of vanadium and benzenedicarboxylate (BDC). The reduction of Cu to Cu has been observed in CuCl2/MIL-47 compounds without high-temperature calcination for the partial reduction. Moreover, CuCl2/ MIL-47 compounds have been prepared by a simple process of loading CuCl2 in the MIL-47 (purified at 70 8C) at room temperature. To understand the contribution of loaded CuCl2 to the adsorptive removal of BT, adsorption was done for various times over CuCl2(0.05)/MIL-47 and MIL-47. Here, MIL-47 is the MIL-47 purified in N,N-dimethylformamide (DMF) at 70 8C (see the Supporting Information). CuCl2(n)/MIL-47 denotes CuCl2 loaded onto the purified MIL-47 and n is the Cu/V ratio (mol/mol). The amount of adsorbed BT over CuCl2(0.05)/MIL-47 is much higher than that over MIL-47 without CuCl2 at all adsorption times (Figure 1). However,

Chemical and Thermal Stability of Isotypic Metal–Organic Frameworks: Effect of Metal Ions

Chemical and thermal stabilities of isotypic metal-organic frameworks (MOFs) like Al-BDC (Al-benzenedicarboxylate called MIL-53-Al), Cr-BDC (MIL-53-Cr) and V-BDC (MIL-47-V), after purification to remove uncoordinated organic linkers, have been compared to understand the effect of the central metal ions on the stabilities of the porous MOF-type materials. Chemical stability to acids, bases, and water decreases in the order of Cr-BDC>Al-BDC>V-BDC, suggesting stability increases with increasing inertness of the central metal ions. However, thermal stability decreases in the order of Al-BDC>Cr-BDC> V-BDC, and this tendency may be explained by the strength of the metal-oxygen bond in common oxides like Al(2)O(3), Cr(2)O(3), and V(2)O(5). In order to evaluate precisely the stability of a MOF, it is necessary to remove uncoordinated organic linkers that are located in the pores of the MOF, because a filled MOF may be more stable than the same MOF after purification.

Adsorption and removal of phthalic acid and diethyl phthalate from water with zeolitic imidazolate and metal–organic frameworks

ZIF-8 (zinc-methylimidazolate framework-8), one of the zeolitic imidazolate frameworks (ZIFs), has been used for the removal of phthalic acid (H2-PA) and diethyl phthalate (DEP) from aqueous solutions via adsorption. The adsorption capacity of the ZIF-8 for H2-PA was much higher than that of a commercial activated carbon or other typical metal-organic frameworks (MOFs). Because the surface area and pore volume of the adsorbents showed no favorable effect on the adsorption of H2-PA, the remarkable adsorption with ZIF-8 suggests a specific favorable interaction (electrostatic interaction) between the positively charged surface of ZIF-8 and the negatively charged PA anions. In addition, acid-base interactions also have a favorable contribution in the adsorption of H2-PA, based on the adsorptive performances of pristine and amino-functionalized MOFs and adsorption over ZIF-8 at acidic condition (pH=3.5). The reusability of ZIF-8 was also demonstrated after simple washing with methanol. On the other hand, ZIF-8 was not effective in adsorbing DEP probably because of little charge of DEP in a water solution.