Carcinogenic arsenic pollution in ground water seriously threatens the health and lives of humans all over the world. It is highly desirable to fabricate new materials for sustainable arsenate removal with high capacities, stabilities and recyclabilities. In this study, we demonstrate that uniform magnetic core-shell structured Fe₃O₄@Resorcinol-Formaldehyde@mesoporous TiO₂ microspheres (denoted Fe₃O₄@RF@mTiO₂) can function as excellent adsorbents for the fast removal of arsenate (As^V) in acidic environments with very high efficiency. The mesoporous TiO₂ outer shell (50 nm in thickness) endows them with a high surface area of 337 m² g^-1 and a large pore volume of 0.42 cm³ g^-1, thus resulting in a fast adsorption rate (1.16 g mg^-1 h^-1) and a high adsorption capacity (up to 139 mg g^-1) calculated using the Langmuir model at a pH of 3. The inner Fe₃O₄ core (130 nm in diameter) makes separation facile from wastewater using a magnet. Moreover, the hydrophobic properties of the RF interlayer (10 nm in thickness) are increased after calcination at 200 °C, and this can protect the inner Fe₃O₄ cores against etching from acid solutions over long cycles. In addition, the study of the As^V adsorption mechanism on the core-shell mesoporous Fe₃O₄@RF@mTiO₂ microspheres shows the existence of electrostatic forces and surface complexation interactions between arsenate and partially crystallized TiO₂. Benefiting from all of these advantages, the multilayer magnetic core-shell structured design is expected to be a promising nanomaterial for long-term wastewater treatment.

Yujuan Zhao;Changyao Wang;Shuai Wang;Chun Wang;Yupu Liu;Areej Abdulkareem Al-Khalaf;Wael N. Hozzein;Linlin Duan;Wei Li;东元 赵

Inorganic Chemistry Frontiers

2018-9

Graphitic carbons with ordered mesostructure and high surface areas (of great interest in applications such as energy storage) have been synthesized by a direct triblock-copolymer-templating method. Pluronic F127 is used as a structure-directing agent, with a low-molecular-weight phenolic resol as a carbon source, ferric oxide as a catalyst, and silica as an additive. Inorganic oxides can be completely eliminated from the carbon. Small-angle XRD and N 2 sorption analysis show that the resultant carbon materials possess an ordered 2D hexagonal mesostructure, uniform bimodal mesopores (about 1.5 and 6 nm), high surface area (∼ 1300m ²/g), and large pore volumes (∼ 1.50 cm ³/g) after low-temperature pyrolysis (900 °C). All surface areas come from mesopores. Wide-angle XRD patterns demonstrate that the presence of the ferric oxide catalyst and the silica additive lead to a marked enhancement of graphitic ordering in the framework. Raman spectra provide evidence of the increased content of graphitic sp ² carbon structures. Transmission electron microscopy images confirm that numerous domains in the ordered mesostructures are composed of characteristic graphitic carbon nanostructures. The evolution of the graphitic structure is dependent on the temperature and the concentrations of the silica additive, and ferric oxide catalyst. Electrochemical measurements performed on this graphitic mesoporous carbon when used as an electrode material for an electrochemical double layer capacitor shows rectangularshaped cyclic voltammetry curves over a wide range of scan rates, even up to 200 mV/s, with a large capacitance of 155 F/g in KOH electrolyte. This method can be widely applied to the synthesis of graphitized carbon nanostructures.

Wenjun Gao;Ying Wan;Yuqian Dou;东元 赵

Advanced Energy Materials

2011-1-1

Limonene dioxide is a platform molecule for the production of new biopolymers. First attempts at limonene epoxidation were made by using low-coordination titanium supported on SBA-16 as the catalyst using tert-butyl hydroperoxide as the oxidizing agent, but no limonene dioxide was obtained. When limonene was substituted by 1,2-limonene oxide, the yield of limonene dioxide was only 13% in the same conditions. Two other techniques, both using in situ generated dimethyl dioxirane by the reaction of acetone with Oxone, have been studied and compared. These reactions are carried out in semibatch conditions and at room temperature. The first double epoxidation of limonene was performed in a conventional biphasic organic-water system and the other in excess acetone. The former epoxidation of limonene using ethyl acetate as the organic phase allowed reaching 95% conversion and yielding 33% of limonene dioxide. In comparison, when the reaction was performed in acetone, a limonene dioxide yield of 97% was observed under optimized conditions. The double epoxidation of limonene should be carried out at room temperature with a flowrate of 4 mL min^-1 of aqueous Oxone for a period of 45 min with a stoichiometric excess of 30% of Oxone.

Luc Charbonneau;Xavier Foster;东元 赵;Serge Kaliaguine

ACS Sustainable Chemistry and Engineering

2018-4-2

Understanding the unique characteristics of continuous-flow photochemistry will lead to a paradigm shift in the way we enhance sustainability and wellbeing. In this mini-review, we first provide a succinct overview of working principles of this technique and discuss several recent synthetic protocols. Then, emphasis is given to those representative examples which address environmental issues such as indoor air pollutants and water contamination. Finally, recent progress made using this technique to deal with rising CO₂ emission, solar energy utilization and biomedical equipment is described. It is believed that this mini-review could inspire more chemists to utilize this technique in their research, either in the academic or industrial field.

Jingli Xie;东元 赵

Chinese Chemical Letters

2020-9

Synthesis of nanometer-sized mesoporous oxide spheres was reported. The synthesized oxides were silica and alumina. The synthesis was performed in the presence some organic solvent with aqueous ammonia as catalyst to control hydrolysis of tetraethyl orthosilicate (TEOS) and aluminum tri-sec-butoxide. Thermo gravimetric analysis showed that block copolymer templates can be removed between 150 and 350 °C.

Q. Luo;L. Li;Z. Y. Xue;东元 赵

Chemical Research in Chinese Universities

2001-5

This paper describes a versatile in situ etching-growth strategy for the preparation of periodic mesoporous organosilica (PMO) composites with yolk-shell structure, which can generate the void space and construct the outer PMO shells at the same time. The superparamagnetic yolk-shell Fe₃O₄@PMO composites (YS-Fe₃O₄@PMO) with radical mesochannels were also synthesized with this unique in situ etching-growth strategy by using Fe₃O₄@nSiO₂ nanoparticles as the initial core. This method provides a general route for the synthesis of yolk-shell structured nanomaterials with different sized void spaces, various chemical composition cores, as well as organic functional PMO shells with radical mesochannels. Moreover, we can also obtain asymmetric or asymmetric hollow Fe₃O₄@PMO materials with a cubic PMO shell. All the magnetic mesoporous composites possess very high surface areas and large pore volumes (586 m² g^-1 and 0.52 cm³ g^-1 for YS-Fe₃O₄@PMO, 946 m² g^-1 and 0.86 cm³ g^-1 for asymmetric hollow Fe₃O₄@PMO). Gold nanoparticles could be encapsulated and confined in the void space of YS-Fe₃O₄@PMO composites through an in situ salt impregnation. The resultant YS-Fe₃O₄@Au@PMO nanomaterials could be used to catalyze the reduction of 4-nitrophenol with an ultrahigh efficiency (k = 0.01197 s^-1). The magnetic catalysts could be easily recovered by a magnet and reused for more than 10 cycles with efficiency retained as high as 95%.

Yong Wei;Xiaomin Li;Ahmed A. Elzatahry;Renyuan Zhang;Wenxing Wang;Xueting Tang;Jianping Yang;Jinxiu Wang;Daifallah Al-Dahyan;东元 赵

RSC Advances

2016

Cu(II)/SnO₂ catalyst materials with Cu:Sn ratios in the range 0.02-0.30 have been prepared by three routes: coprecipitation from aqueous solutions containing Cu²⁺ and Sn⁴⁺ ions, sorption of Cu²⁺ ions on to tin(IV) oxide gel, and destabilization of choline-stabilized tin(IV) oxide colloidal sols by the addition of aqueous copper(II) nitrate solution, and their constitution after thermal treatment in the temperature range 333-1273 K has been investigated by powder X-ray diffraction and EXAFS. Materials obtained by coprecipitation or impregnation are similar in nature irrespective of the Cu:Sn ratio with particle sizes <5 nm even after calcination at 673 K. Calcination at 873 K results in larger particles, but at temperatures ≥1073 K sintering to give very large particles occurs. EXAFS data show that the initial Cu(II) species from the coprecipitation or impregnation routes are hexaaqua {Cu(H₂O)₆}²⁺ ions sorbed onto the surface of the tin(IV) oxide particles but calcination at temperatures of 873 K and above causes the phase separation of CuO. EPR shows that only surface copper(II) is readily reduced on exposure to carbon monoxide. Copper(II)-promoted tin(IV) oxide catalysts effect the catalytic oxidation of CO for stoichiometric CO/O₂ mixtures under at 328 K. The mode of operation of the catalysts appears to be synergistic in nature with the principal role of Cu(II) being mainly in electron transfer, i.e., it abstracts the negative surface charges (formed in the oxygen vacancies following desorption of CO₂) to form Cu(I), which is then oxidized back to Cu(II) by reaction with oxygen. The activity of catalysts deactivated by running under highly reducing conditions can be restored completely by heating in a flow of air at 355 K. Irreversible deactivation occurs on processing at very high temperatures due to sintering and the phase separation of copper(II) oxide.

Philip G. Harrison;Craig Bailey;Wayne Daniell;东元 赵;Ian K. Ball;Daniella Goldfarb;Nicholas C. Lloyd;Wan Azelee

Chemistry of Materials

1999

The synthesis of stable bicontinuous hierarchically porous metal-organic frameworks (MOFs) is described. Two functional block co-oligomer templates were used independently, i.e. poly(styrene)-block-poly(4-vinylpyridine) and poly(styrene)-block-poly(acrylic acid). Two prototypical MOFs, ZIF-8 and HKUST-1, were selected to demonstrate our approach. The resulting materials resemble the microstructures of bicontinuous silica aerogels. They exhibit interconnected porosities throughout the micro-, meso- and macro-porous regions, as shown by electron microscopy and pore size distribution analyses.

Shuai Cao;Guillaume Gody;Wei Zhao;Sébastien Perrier;Xiaoyu Peng;Caterina Ducati;东元 赵;Anthony K. Cheetham

Chemical Science

2013-7-29

The surface acidity and hydroxyl vibrations of the pillared clay molecular sieve containing mixed metal complexes were determined by IR spectra. The results suggest that (1) the clay and pillared clays have more Lewis acid sites than Bronsted acid sites; (2) their surface acidity is varied with the pillaring agents and comes from their pillars, which can be transfered into oxides and release protons and produce Bronsted and Lewis acid sites after calcination; (3) the hydroxyl groups (3500-3700 cm^MIN1) are originated mainly from the aluminum located on the octahedral skeleton and their intensities decrease with the increase in temperature; (4) the stability of the pillars in the pillared clays affects their surface hydroxyl groups and Bronsted and Lewis acid sites.

东元 赵;Yashu Yang;Qin Xin;Hui Zhang;Xiexian Guo

Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis

1994-8

The effects of aging and drying conditions on the structural and textural properties of surfactant-templated silica xerogel with bimodal mesopore distribution characteristic (designated as BMS) prepared under base-catalyzed sol-gel process were investigated. It was found that the change of aging and drying conditions would influence not only the size and the packing geometry of surfactant-encapsulated silica primary particles, in turn the textural mesoporosity, but also the polymerization extent of framework pore wall which would determine the framework mesopore properties. Both the lower aging temperature and the higher drying temperature are conducible to the formation of a high-quality BMS silica xerogel. However, over the range studied, aging and drying conditions had no significant effect on the framework mesopore sizes, though the corresponding specific surface areas and pore volumes can be varied markedly.

X. Wang;W. Li;B. Zhong;东元 赵

Studies in Surface Science and Catalysis

2004