Sung Hwa Jhung

Severe industrialization causes adverse impacts on human beings because of the contamination of water with toxic and undegradable organic contaminants such as phenolic compounds (PCs). Here, some nitrogen-rich carbonaceous materials, CDC(x)s, have been first prepared through the two-step carbonization of a covalent-organic framework SNW-1 (Schiff-based network-1). SNW-1 was pyrolyzed; the obtained product and potassium hydroxide mixtures were again pyrolyzed under different temperatures to get CDC(x)s. The carbonaceous materials were characterized and applied in the adsorptive elimination of para-nitrophenol (pNP, one of the representative PCs) from water. One CDC(x) called CDC(800) had a very high maximum adsorption capacity (Qo), 1190 mg/g (at pH 7) which is 6 times that of activated carbon, and higher than that of any other known materials. Based on the adsorption results under …

Recently, contamination of water resources with organic pollutants has been serious in many countries. Elimination of such organics from water can be carried out via adsorption using metal–organic frameworks (MOFs) or MOF-derived carbons (MDCs). In this review, the progress in the adsorptive removal of organics with MOFs or MDCs is summarized. Especially, the investigated adsorption or adsorption mechanism is analyzed based on the functional groups (FGs, like –COOH, –OH, –NO2, –NH2, –SO3H, etc.) on the organics or adsorbates rather than the adsorption of various organics by using MOFs or MDCs composed of specific FGs (which has been the general approach, so far). Developing an adsorption technology would be more efficient through analyzing the adsorption based on the FGs present in the adsorbates, rather than focusing on the FGs in the adsorbents. In other words, promising adsorbents …

In this work, the preparation, functionalization, and properties (including strong and weak points) of four highly studied (in recent days) porous materials like metal-organic frameworks (MOFs), MOF-derived carbons, covalent-organic frameworks (COFs), and COF-derived carbons are analyzed. Next, the progress on the adsorption of pharmaceuticals like sulfamethoxazole, diclofenac, and carbamazepine (that are the top three most frequently observed pharmaceuticals in water) over the four adsorbents is also analyzed in order to understand the competitiveness of the adsorbents and possible applications. After a summary of the work, the next potential research or future perspectives are suggested.

A highly porous covalent-organic polymer with mesoporosity (named MT-MCTP) was prepared for the first time via ZIF-8 (a zeolitic imidazolate framework, comprised of ZnN4 tetrahedral units interconnected by methyl imidazolate linkers) templated synthesis of microporous triazine polymer (MCTP) and subsequent removal of ZIF-8. MT-MCTP had higher porosity and wider pore size than the conventional MCTP. The prepared MT-MCTP, together with MCTP and commercial activated carbon (AC), was applied to the adsorptive elimination of sulfonamides like sulfamethoxazole and sulfachlorpyridazine from water. MT-MCTP showed the highest kinetic constants among the three adsorbents in the sulfonamides adsorption because of the developed mesopores obtained with the sacrificial ZIF-8 template. Additionally, the adsorbed amounts of sulfamethoxazole and sulfachlorpyridazine over the adsorbents decreased in …

The discovery of low-cost, highly effective, and novel catalytic materials for oxidative desulfurization (ODS) of liquid fuel is an important topic in the field of heterogeneous catalysis from both academic and industrial viewpoints. Different metallic active component supported on porous carbon was found as effective catalysts for ODS reactions and the contribution of the secondary or non-metallic heteroatom decoration on the carbon was also assumed. However, the precise role of the doped heteroatom(s) on boosting the ODS process is unknown. Here, a new approach to prepare a series of cobalt-anchored porous carbon (Co@C) with different heteroatom co-dopants (i.e., N, P, and B) and their effects on boosting oxidative desulfurization (ODS) from fuel were firstly instigated. The Co@nitroneneous carbons with P or B co-dopants could be derived via the carbonization of a bimetallic MOF with extra N, P, and B …

Aerobic oxidative denitrogenation (ODN) of a model fuel was first done with metal-free P and O co-doped carbon catalysts. The catalysts, phytic acid (PA)-loaded polyaniline-derived carbons (PPDCs), were firstly prepared by high-temperature pyrolysis of polyaniline with phytic acid (as P/O sources). One material, PPDC-2 showed a conversion of 95 % and 86 % for indole (IND) and quinoline (500 ppm each), respectively, at 100 °C, with O2 as an oxidant. A very small activation energy of 26.6 kJ mol−1 was observed in the IND oxidation. Radical trapping experiments and electron spin resonance spectroscopy analyses supported the formation of superoxide anion radicals (O2radical dot−) from the fed O2, which was responsible for the IND oxidation. A plausible reaction mechanism was proposed by analyzing the experimental results and DFT calculations on charge separations on carbons. Defect sites also could …

Preventing the increase of CO2 content in the atmosphere is crucial to mitigating climate change. In this study, we investigated the adsorption of CO2 using isostructural Cr-based MOFs, MIL-101 and MIL-100, after grafting diaminoalkanes with various chain lengths to determine the effect of the geometric configuration of the amines and to develop a competitive adsorbent. The performance of CO2 adsorption (e.g., adsorption capacity, selectivity, and adsorption heat) over MIL-101 increased as the size of diaminoalkanes increased, topped with 1,4-butanediamine, and declined with longer diaminoalkanes. The favorable contribution of grafted 1,4-butanediamine in increasing the performances in CO2 adsorption could be explained by the adequate size of the amines for the optimized configuration in the pore window of the MIL-101. However, interestingly, none of the MIL-100s grafted with diaminoalkanes showed a …

In this review, metal–organic frameworks functionalized with nitro groups (MOF-NO2s) were analyzed, for the first time, in terms of their preparation and applications. MOF-NO2s were obtained by direct synthesis from nitro-functionalized linker precursors and by post-synthetic modification of a pristine MOF without a –NO2 group. Additionally, the applications of MOF-NO2s, specifically in adsorption and catalysis, were discussed. CO2 capture using MOF-NO2s was highly effective due to the polar nitro group which aided in quadrupole–dipole interactions. Furthermore, on account of the electron-withdrawing nitro group, MOF-NO2s were efficient in the adsorption of other gases, such as nitrogen. Similarly, MOF-NO2s were promising for the removal of hazardous organics from water and particulate matter from the air mainly due to the charge separation on the nitro group. MOF-NO2s could be very useful in catalysis that …

Adsorptive removal of aromatic diamines such as methylenedianiline (MDA) and p-phenylenediamine (PPD) was firstly investigated with nitro-functionalized metal-organic frameworks (MOFs, MIL-101(Cr)-NO2). The MIL-101(Cr)-NO2 showed much better performances in the removal of MDA and PPD, in both adsorption capacity and kinetics, than any other adsorbents. For example, MIL-101(Cr)-NO2 had a much higher maximum adsorption capacity for MDA (1111 mg·g−1) than activated carbon (208 mg·g−1) or a reported adsorbent (391 mg·g−1). Based on experimental results, hydrogen bonding (especially, via the formation of a 6-membered ring (6-MR) between -NO2 of the adsorbent and -NH2 of the adsorbates) could be suggested as the main mechanism to interpret the noticeable adsorption of the diamines. Importantly, this is the first example to confirm that MOFs with nitro group can be a competitive …

SSZ-13 is an attractive zeolite with chabazite topology composed of small pores with 8-membered rings. In this work, we report a highly effective method to synthesize SSZ-13s with microwave (MW) heating. Compared with conventional electric (CE) heating, MW heating accelerates both the nucleation and crystal growth rates of the synthesis by 6 and 18 times, respectively. Importantly, MW-assisted rapid synthesis produces the SSZ-13 with the smallest particles (<50 nm). However, the CE-assisted synthesis produces large/inhomogeneous particles (size: 0.4–1 μm). The obtained SSZ-13s were employed in acid catalysis or ethylene-to-propylene (ETP) reactions. The record-small SSZ-13s were more efficient in the ETP reactions, with more stable ethylene conversion/propylene yield (at the same time on stream) and higher propylene selectivity (at the same ethylene conversion), than large SSZ-13s. Finally, the …

Two flexible tetracarboxylic acids with ether (H4AOIA) and amine (H4ANIA) linkages have been employed for the formation of two distinct Co-metal–organic frameworks (MOFs) with diverse architectures. Both the MOFs were shown to demonstrate remarkable catalytic activities for the chemical conversion of CO2 into cyclic carbonates under ambient reaction conditions with considerably high turnover number values. Further, carbonization of the two-dimensional-MOF, Co-ANIA, under inert atmospheric conditions at a temperature of 800 °C resulted in the formation of cobalt containing N-doped nanocomposite (Co@NPC2). In the context of generation of a sustainable source of energy and to carry out successive conversions, the single-component nanocomposite, Co@NPC2, was shown to act as an efficient cost-effective non-noble metal electrocatalyst through its electrochemical activity toward hydrogen evolution.

Microalgae-derived esterified bio-oil can be an alternative energy source against the depletion of fossil fuel although the content of organonitrogen compounds (ONCs) can be high. Here, a metal–organic framework (MOF, MIL-101-NH2, with or without grafting ethylenediamine, ED) was modified to derive sulfonic acid-functionalized MIL-101 s. The obtained MOFs (including pristine MIL-101 and MIL-101-NH2), together with activated carbon (AC) as a reference, were utilized in adsorptive denitrogenation (ADN), especially the removal of carbazole (CBZ), one of the most difficult ONCs via hydrogenation or oxidation, from model fuel composed of methyl laurate. Although there was a study on ADN from model fuel composed of very light esters like methylacetate, there is no report using esters that are quite similar to fatty acid methyl esters of oils. Remarkably, MIL-101-NH-ED-SO3H, the first MOF having sulfonic acids …

Voltammetric sandwich assays were constructed by integrating capture bioreceptors-conjugated magnetic nanocomposites, namely Fe3O4/MIL-101(Fe)-(NH)(CO)-COOH (FO/MOF) and alkaline phosphatase (ALP)-labeled detection antibodies on an eight-well screen-printed carbon ink electrode (SPCIE) for the simultaneous detection of liver cancer biomarkers, human tissue transglutaminase 2 (TGM2) and heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1). Magnetic FO/MOF nanocomposites were prepared via a simple microwave-assisted method; these not only provided large surface areas for covalently attaching capture bioreceptors, but also acted as a separator for the sandwich nanocomposites magnetically isolated from solutions. TGM2 and hnRNP A1 were first adsorbed onto anti-TGM2 (JU30–02)- and hnRNP A1 aptamer-FO/MOF conjugates, respectively, in buffer or serum followed by the …

A nitrogen and sulfur co-doped carbon was prepared from a covalent-organic polymer named microporous triazine polymer (MCTP) for the first time by loading NH4NO3 and diphenyldisulfide followed by pyrolysis. The obtained carbons (named NSMDCs) were exploited as environment-friendly metal-free catalysts for oxidative desulfurization of organo sulfurous compounds (OSCs) from a dodecane-based simulated fuel using molecular oxygen (O2) as an oxidizing agent. One of the materials showed a nearly complete conversion of an OSC, dibenzothiophene, after a reaction of 4 h at 100 °C which is one of the lowest temperatures among the metal-free ODS catalyses. A very low activation energy (Ea) of 30.4 kJmol−1 was found for the DBT oxidation which is also lower than or competitive against most of other reported results (including the ones using metal-based catalysts). Radical scavenging investigations and …

Selective and effective capture of CO2 from off-gases or even from the atmosphere is very important to prevent global warming. Recently, CO2 adsorption using porous materials has attracted much attention because of its high efficiency and the low corrosiveness of porous adsorbents. Especially, metal–organic frameworks (MOFs, typical porous materials) have been deeply studied for CO2 adsorption because MOFs have strong points like very high porosity, designable structure, and ready modification. Functionalized MOFs have been very useful in CO2 adsorption in increasing the adsorption capacity, selectivity, and heat of adsorption although the porosity could be reduced by loading functional groups (FGs) onto the MOFs. In this review, we analyzed comprehensively the contribution of FGs (excluding the well-known amino group) of MOFs to CO2 adsorption under low pressure. Although there have been a few …

Vanadium nitride was firstly applied to oxidative desulfurization (ODS) of liquid fuel. Carbon-supported vanadium nitride (VN@C) was prepared from pyrolysis of urea-loaded MOF, MIL-100(V), especially in the absence of external ammonia flow. One catalyst prepared at 1100 °C, VN@C(1100), had the highest turnover frequency of 18.8 h−1 (with a very low activation energy of 29.9 kJmol-1) among the reported vanadium-based catalysts. The ESR and scavenger experiments confirmed •OH radical was the active species for the ODS. Calculations using density functional theory could support the beneficial role of VN (compared with conventional oxides) both in the adsorption of H2O2 and •OH and H2O2 activation to form •OH radical. The VN@C(1100) catalyst could be used for five cycles without any loss in activity. Therefore, supported vanadium nitrides could be suggested as a potential catalyst for oxidations that …

Functionalized metal–organic frameworks (MOFs) are very popular because of their various applications, designable functional sites, and facile preparation. MOFs composed of a hydroxy group on linkers or on grafted species are also attractive based on the possible applications of loaded –OH groups. In this review, MOFs with –OH groups (termed MOF-OHs) will be discussed in the view of both preparation and applications. Direct synthesis from linker precursors having –OH groups and post-synthetic modification will be delineated for the preparation of MOF-OHs. The applications of MOF-OHs in adsorption, catalysis, and sensing will also be dealt. This review shows that MOF-OHs can be facilely prepared via direct synthesis and post-synthetic modification; have various applications in adsorption, catalysis, etc. mainly because of the contribution of the loaded hydroxy groups. Finally, future prospects will be …

Nitrogen-doped porous carbons are one of the most fascinating materials with noticeable applications in adsorption/separations, catalysis, supercapacitors, and batteries. Polyaniline (pANI)- or polypyrrole (pPYR)-derived carbons (pADCs or pPDCs, respectively) exhibit very remarkable performances in the liquid- and gas-phase adsorptions because of some unique characteristics including nitrogen- and oxygen-functionalities, very high specific surface area, and tailored porosity. In this report, we reviewed the recent advances in the preparation and characterization of pADC- and pPDC-type materials and their applications in the adsorptive removal/separation of various chemicals from water, liquid fuel, and air. The preparation procedures and the surface properties of the reported pADC or pPDC adsorbents were explained, with adequate tables. The adsorption results were discussed in terms of the following …

A zeolite named SSZ-13, with a small pore of 8-membered rings, is an attractive porous material for DeNOx, CO2 capture/separation, methanol-to-olefin conversion, and direct conversion of ethylene to propylene (DCEP). Although the synthesis of SSZ-13 has been done for a long time and is useful for some applications, further development in the synthesis is required to reduce the production cost or to optimize the preparation. On the other hand, the utilization of waste is important for our sustainability. In this study, SSZ-13 zeolite was synthesized using rice husk-derived silica, for the first time, in order to prepare SSZ-13 at a low cost and utilize agricultural byproducts in zeolite synthesis. Via this research, it was found that SSZ-13s could be synthesized readily by using rice husk-derived silica even without seed crystals. Synthesis at 180 °C for 5–7 d leads to SSZ-13 from the gel with a wide range of silica/alumina …

Metal-organic frameworks (MOFs) are popular porous materials prepared from metallic species and organic linkers via the formation of coordination bonds. The applications and potentiality of MOFs can be further improved by their functionalization, such as the introduction of functional groups into pristine MOFs. Among these functional groups, the –OH group is interesting because of its polarity and weak acidity for hydrogen bonding and acid catalysis, respectively, for example. The hydroxyl group can be loaded onto both the linker and metal sites. In this review, the –OH groups on the metallic species of MOFs are discussed because various MOFs contain hydroxo groups as ligands. MOFs bearing hydroxo ligands (MOF-HLs) are attractive because no functionalized linker (that is useful for MOFs with –OH on the linkers) or modification/functionalization is required during their preparation, unlike MOFs composed of …