• Journal of Korean Society of Water and Wastewater
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• v.21 no.1
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• pp.139-147
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• 2007

For environmental remediation of a contaminated groundwater plume, the use of zero-valent metal represents one of the latest innovative technologies. In this study, the effects of denitrification by zero-valent iron adsorbed in mesoporous silicas have been studied for groundwater contaminant degradation. The mesoporous silica was functionalized with 3-mercaptopropyltrimethoxysilane (MPTS) ligands and the zero-valent iron precipitated in the mesopore of granular silica was made by $FeCl_2$ and $NaBH_4$. Hydrogen was exchanged with $Fe^{2+}$ ions in the granular silicas. And then the ions were reduced by sodium borohydride in the mesoporous silicas. The surface area of the silica determined via the BET method ranged from 858 to $1275m^2/g$. The reductive reaction of nitrate-nitrogen indicated that the degradation of nitrate-nitrogen appeared to be pseudo first-order with the observed reaction rate constant kobs ($0.1619h^{-1}$) and to be directly proportional to the specific surface area. Therefore, the mesoporous silica with nano zero-valent iron proposed as a novel treatment strategy for contaminated groundwater was successfully implemented herein for the removal of nitrate-nitrogen.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3711-3718
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• 2012

Here, we report a chain-length dependent morphology and pore structure tailing of mesoporous silica templated from organogels, which is formed by primary alkylamine and ethylene glycol at room temperature. As the chain length of alkylamine changes from 12 to 18, the resulted materials exhibit a morphology change from layers to spheres and platelets, respectively. SEM and TEM observation revealed that these shapes appear to be inherited from their parent organogels. Further pore structure characterization by nitrogen sorption analysis demonstrates that all the resulted silicas exhibit typical IV isotherms indicative of uniform mesopores, and their pore sizes are dependent on the chain length of alkylamine used.

• Clean Technology
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• v.17 no.1
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• pp.13-18
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• 2011

Phosphine ligand-grafted mesoporous silica materials with large pores were prepared for the ligand-modified heterogeneous Pd nanocatalysts. New heterogeneous catalytic system was developed using palladium nanoparticles encapsulated in phosphine ligand-grafted mesoporous silica. The catalyst showed good catalytic activities for Suzuki cross-coupling using bromobenzene derivatives due to excellent phosphine ligand effects. Catalytic results showed nanoparticie catalysts can be recycled twice with decreased yields.

• Journal of Environmental Science International
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• v.16 no.6
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• pp.689-698
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• 2007

Mesoporous silicas for heavy metals adsorption were prepared by co-condensation of surfactant as a template and Ludox HS-40 as a silica precursor. Various mesoporous silicas with the introduction of chelating ligands (mercaptopropyl and aminopropyl groups) were synthesized to remove heavy metal ions from aqueous solutions. The surface modification was conducted with a co-condensation process using the sequential or simultaneous addition of mesoporous silica and high concentration of the organosilane(3-mercaptopropyltrimethoxysilane and 3-aminopropyltriethoxysilane). These materials have been characterized by elemental analysis, XRD, SEM and TEM analysis. Adsorbents synthesized with 3-mercaptopropyltrimethoxysilane and 3-aminopropyltriethoxysilane shows a high loading capacity for Hg(II), Pb(II), Cd(II) and anion Cr(VI). Especially the one synthesized with a mercaptopropyl function has the highest adsorption capacity for Hg(II) and Cd(II).

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.210-218
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• 2018

Ethylenediaminetetraacetic acid (EDTA)-functionalized KIT-6 and KCC-1 mesoporous silicas were prepared via post-synthesis grafting and examined for their ability to promote the recovery of rare earth metal ions such as $Nd^{3+}$ from an aqueous medium. The obtained adsorption isotherms were fitted to the Langmuir model, which gave a maximum adsorption of $Nd^{3+}$ ions of 109.8 and 96.5 mg/g for KIT-6-EDTA and KCC-1-EDTA, respectively, at $25^{\circ}C$ and pH 6. The adsorption kinetic profile of KIT-6 was faster than KCC-1. KIT-6 was also proved to be more stable against desorption under acidic regeneration conditions.

• Applied Chemistry for Engineering
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• v.27 no.2
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• pp.190-194
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• 2016

Tricyclopentadiene (TCPD) is one of the important precursors for making tetrahydrotricyclopentadiene, which is well known as a next-generation fuel with high energy density. In this study, TCPD was obtained by polymerization reaction of dicyclopentadiene (DCPD) using an ionic liquid (IL) supported mesoporous silica catalysts. ILs were supported to two kinds of mesoporous silica catalysts with different pore sizes such as MCM-41 and SBA-15. Four different ILs were supported to mesoporous silicas using anionic precursors such as CuCl or $FeCl_3$ and cationic precursors such as triethylamine hydrochloride or 1-butyl-3-methylimidazolium chloride. We proved that IL supported mesoporous silicas showed better catalytic performance than those of using non-supported prestine IL in the aspect of TCPD yield and DCPD conversion. Among four kinds of IL supported mesoporous silica catalysts, CuCl-based IL supported MCM-41 system showed the highest TCPD yield.

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1653-1668
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• 2005

Assembly of hybrid mesophases through the combination of amphiphilic block copolymers, acting as structuredirecting agents, and silicon sources using low acid catalyst concentration regimes is a versatile strategy to produce large quantities of high-quality ordered large-pore mesoporous silicas in a very reproducible manner. Controlling structural and textural properties is proven to be straightforward at low HCl concentrations with the adjustment of synthesis gel composition and the option of adding co-structure-directing molecules. In this account, we illustrate how various types of large-pore mesoporous silica can easily be prepared in high phase purity with tailored pore dimensions and tailored level of framework interconnectivity. Silica mesophases with two-dimensional hexagonal (p6mm) and three-dimensional cubi (Fm$\overline{3}$m, Im$\overline{3}$m and Ia$\overline{3}$d) symmetries are generated in aqueous solution by employing HCl concentrations in the range of 0.1−0.5 M and polyalkylene oxide-based triblock copolymers such as Pluronic P123 $(EO_{20}-PO_{70}-EO_{20})$ and Pluronic F127 $(EO_{106}-PO_{70}-EO_{106})$. Characterizations by powder X-ray diffraction, nitrogen physisorption, and transmission electron microscopy show that the mesoporous materials all possess high specific surface areas, high pore volumes and readily tunable pore diameters in narrow distribution of sizes ranging from 4 to 12 nm. Furthermore, we discuss our recent advances achieved in order to extend widely the phase domains in which single mesostructures are formed. Emphasis is put on the first synthetic product phase diagrams obtained in $SiO_2$-triblock copolymer-BuOH-$H_2O$ systems, with tuning amounts of butanol and silica source correspondingly. It is expected that the extended phase domains will allow designed synthesis of mesoporous silicas with targeted characteristics, offering vast prospects for future applications.

• Journal of the Korean Chemical Society
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• v.52 no.2
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• pp.155-163
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• 2008

.A simple and reproducible method for the rapid extraction and determination of trace amounts of copper(II) ions using mesoporous organo-silicas mesoporous silica and atomic absorption spectrometry is presented. Common coexisting ions did not interfere with the separation and determination. The preconcentration factor was 100 (1 ml elution volume) for a 100 ml sample volume. The limit of detection of the proposed method is 1.0 ng ml-1. The maximum sorption capacity of sorbent under optimum conditions has been found to be 5mg of copper per gram of sorbent. The relative standard deviation under optimum conditions was 2.8% (n=10). Accuracy and application of the method was estimated by using test samples of natural and synthetic water spiked with different amounts of copper(II) ion.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3570-3576
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• 2013

Poly(methacrylic acid)-functionalized SBA-15 silicas (denoted as P-x-PMA/SBA-15 where x is molar ratio of TSPM/(TEOS+TSPM) in percentage in the initial mixture) were synthesized by co-condensation of tetraethoxysilane and varying contents of 3-(trimethoxysilyl)propyl methacrylate in acidic medium with the block copolymer Pluronic 123 as a structure directing agent and then polymerization by methacrylic acid in the presence of ammonium persulfate as an initiator. The functionalized materials were characterized by PXRD, TEM, SEM, IR, and $N_2$ adsorption-desorption at 77 K. The investigation of phenol adsorption in aqueous solution on the materials showed that the poly(methacrylic acid)-functionalized mesoporous silicas possess strong adsorption ability for phenol with interaction of various kinds of hydrogen bonds. The adsorption data were fitted to Langmuir isotherms and the maximum adsorption capacity of the three functionalized materials P-5-PMA/SBA-15, P-10-PMA/SBA-15, and P-15-PMA/SBA-15 to be 129.37 mg/g, 187.97 mg/g, and 78.43 mg/g, respectively, were obtained. The effect of the pH on phenol adsorption was studied.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.2961-2965
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• 2012

Mesoporous carbons with tailored pore size were prepared by using sucrose as the carbon source and silicas as the templates. The silica templates were obtained from a hydroxypropyl-${\beta}$-cyclodextrin-silica hybrids using ammonium perchlorate oxidation at different temperatures to remove the organic matter. The structures and surface chemistry properties of these carbon materials were characterized by $N_2$ adsorption, TEM, SEM and FTIR measurements. The catalytic performances of these carbon materials were investigated through the reduction of nitroaromatic using hydrazine hydrate as the reducing agent. Compared with other carbon materials, such as active carbon, and carbon materials from the silica templates obtained by using calcination to remove the organic matter, these carbon materials exhibited much higher catalytic activity, no obvious deactivation was observed after recycling the catalyst four times. Higher surface area and pore volume, and the presence of abundant surface oxygen-containing functional groups, which originate from the special preparation process of carbon material, are likely responsible for the high catalytic property of these mesoporous carbon materials.