Carbon nanocage: a large-pore cage-type mesoporous carbon material as an adsorbent for biomolecules

Novel large pore cage type mesoporous carbons, carbon nanocages, abbreviated as CKT (carbon from KIT-5) using three dimensional large cage type face centered cubic Fm3m mesoporous silica materials (KIT-5) as inorganic templates prepared at different temperature were synthesized and characterized. The specific pore volume and the specific surface area of the carbon nanocage materials are much higher as compared to CMK-3 mesoporous carbon. Adsorption of amino acid (histidine), flavonoid (catechin), vitamin (vitamin E, α-tocopherol), endocrine disrupter (nonylphenol), and enzyme (lysozyme) over the carbon nanocage materials was also studied. Interestingly, carbon nanocage materials showed an unusual adsorption capacity of catechin in aqueous solution. The CKT carbon nanocage materials also exhibited higher adsorption capabilities of other biomolecules used in this study as compared with the CMK-3 mesoporous carbon.     

Template synthesis of large pore ordered mesoporous carbon

Nanocast carbon (NCC-1) with large pores and ordered structure was synthesized via a nanocasting process using aluminum-containing SBA-15 as template and furfuryl alcohol (FA) as carbon precursor. This carbon has several interesting features, such as two steps with distinguished hystereses in the nitrogen sorption isotherm, high surface area of 2000 m²/g and large pore volumes of 3.0 cm³/g. It was found that the key factors in the synthesis of such carbons are the aging temperature of the SBA-15 template, the concentration of furfuryl alcohol (dissolved in trimethylbenzene), and the carbonization temperature. The optimal conditions for materials with high surface area and pore volumes are SBA-15 starting materials aged at 140 °C, 25 vol% of FA solution and 850–1100 °C carbonization temperatures. Moreover, it has been demonstrated that such nanocast carbon can be synthesized in a more facile way than previously reported. Purely siliceous SBA-15 without the need of Al³⁺-incorporation can be directly used as template. In this case, the polymerization catalyst—oxalic acid and FA were simultaneously introduced into the pore space of SBA-15.     

Template method synthesis of mesoporous carbon spheres and its applications as supercapacitors

Mesoporous carbon spheres (MCS) have been fabricated from structured mesoporous silica sphere using chemical vapor deposition (CVD) with ethylene as a carbon feedstock. The mesoporous carbon spheres have a high specific surface area of 666.8 m²/g and good electrochemical properties. The mechanism of formation mesoporous carbon spheres (carbon spheres) is investigated. The important thing is a surfactant hexadecyl trimethyl ammonium bromide (CTAB), which accelerates the process of carbon deposition. An additional advantage of this surfactant is an increase the yield of product. These mesoporous carbon spheres, which have good electrochemical properties is suitable for supercapacitors.     

Characterization and adsorption behaviors of a novel synthesized mesoporous silica coated carbon composite

A novel mesoporous silica coated carbon composite(denoted SEG) with hierarchical pore structure has been successfully prepared in an aqueous solution that contains triblock copolymer template, aluminum chloride, siliceous source and expanded graphite. Textural property and morphology of the SEG composite were characterized by the combination of X-ray diffraction, N_2 adsorption–desorption, scanning electron microscopy,transmission electron microscopy and Fourier transform infrared measurements. Results show that mesoporous silica is steadily and uniformly grown on the surface of the graphite slices and the thickness of the silica layer can be finely tuned according to the silica/C molar ratio in the initial reaction solution. This newly synthesized SEG composite shows greatly increased adsorption capacity to methylene blue than the pristine expanded graphite in the batch tests. Both Langmuir and Frendlich models were further used to evaluate the adsorption isotherms of methylene blue over expanded graphite and SEG samples with different silica contents. Finally, pseudosecond-order model was used to describe the kinetics of methylene blue over expanded graphite and the silica-carbon composites.     

Controlling the textural parameters of mesoporous carbon materials

The mesoporous carbon materials prepared by inorganic templating technique using mesoporous silica, SBA-15 as a template and sucrose as a carbon source, have been systematically investigated as a function of sucrose to mesoporous silica composition, with a special focus on controlling the mesoporous structure, surface morphology and the textural parameters such as specific surface area, specific pore volume and pore size distribution. All the materials have been unambiguously characterized by XRD, N₂ adsorption–desorption isotherms, high-resolution transmission electron microscopy, high-resolution field emission scanning electron microscopy, and Raman spectroscopy. It has been found that the porous structure, morphology and the textural parameters of the mesoporous carbons materials, CMK-3-x where x represent the sucrose to silica weight ratio, can be easily controlled by the simple adjustment of concentration of sucrose molecules. It has also been found that the specific surface area of the mesoporous carbon materials systematically increases with decreasing the sucrose to silica weight ratio. Moreover, the specific pore volume of the materials increases from 0.57 to 1.31 cm³/g with decreasing the sucrose to silica weight ratio from 5 to 1.25 and then decreases to 1.23 cm³/g for CMK-3-0.8. HRTEM and HR-FESEM also show a highly ordered pore structure and better surface morphology for CMK-3-1.25 as compared to other materials prepared in this study. Thus, it can be concluded that the sucrose to silica weight ratio of 1.25 is the best condition to prepare well ordered mesoporous carbon materials with good textural parameters, pore structure and narrow pore size distribution.     

Templating synthesis of ordered mesoporous carbon particles

This research reports the synthesis of spherical ordered mesoporous carbon particles using mesoporous silica particles as a template. The silica particles with ordered cubic and lamellar mesostructures were synthesized from an aerosol-assisted self-assembly process using block copolymer surfactants as the structural directing agent. Infiltrating the pores of the silica particles with a sucrose solution followed by carbonization, and silica removal results in mesoporous carbon particles with replicated mesostructures. The particles were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and nitrogen sorption techniques.     

Synthesis and characterization of hybrid nano-crystallites inside self-ordered mesoporous carbon

The design and construction of nano-crystallites inside ordered mesoporous carbon is of great interest for potential applications in many fields. One of the main challenges is how to control hybrid nano-crystallites formed inside the pores. We describe a synthesis strategy of impregnation/hydrothermal method for incorporation of hybrid nano-crystallites Ru_0.3Cr_0.7O₂ inside CMK-3 with the average size of the nano-crystallites around 2.8–3.05 nm. The texture/structures of the resultant materials have been characterized by X-ray diffraction, transmission electron microscope, and nitrogen adsorption/desorption measurements. No nano-crystallites are observed to be generated on the external surface of CMK-3. The resultant material exhibits a high specific capacitance of approximately 226 F g⁻¹. This approach is expected to be applied to other hybrid metals oxides synthesized inside CMK-3 with specific structures and properties. Furthermore, it provides a versatile route for expanding the application of ordered mesoporous carbon with diverse pore arrangements.     

One-step preparation,characterization and adsorption property of mesoporous nickel sulfides in deep eutectic solvent

In this paper, single and mixed-phase mesoporous nickel sulfides (including α-NiS/β-NiS/Ni₃S₄, Ni₃S₄, Ni₃S₄/NiS₂ and NiS₂) are prepared in choline chloride-ethylene glycol deep eutectic solvent (ChCl-EG DES) under normal atmosphere. In the preparation processes, the ChCl-EG DES plays dual roles as solvent and template. The effects of NiSO₄·6H₂O, Na₂S₂O₃·5H₂O and ethylenediamine tetraacetic acid concentrations on the phase, morphology, element composition and specific surface area of the products are examined. The results show that pompon-like, cauliflower-like, botryoid and nanospherical nickel sulfides can be obtained by controlling the concentration of the reactants. Their specific surface areas are 4.063 m²/g, 5.138 m²/g, 4.533 m²/g and 52.135 m²/g, respectively. The reaction mechanism for the preparation of nickel sulfides in ChCl-EG DES is also elaborated. In addition, the adsorption property and mechanism of nickel sulfides are assessed with methylene blue (MB) as target organic pollutant. The adsorption process on MB follows the pseudo-second-order kinetics and Langmuir isotherm models. Their maximum adsorption capacity for MB are 20.39 mg g^?1, 19.56 mg g^?1, 21.38 mg g^?1 and 24.38 mg g^?1, respectively.     

Characterization of acidic property of sulfo-group functionalized microporous and mesoporous silica by adsorption microcalorimetry

Sulfo-group functionalized microporous and mesoporous silica based-on a MCM-41 framework which showed solid acid property were synthesized and characterized by adsorption microcalorimetry. Both the sulfo-functionalized microporous and mesoporous silica (Micro-SO₃H and Meso-SO₃H) were prepared by the oxidation of thiol group (–SH) included mesoporous silica which was obtained through the hydrolysis and co-condensation of tetramethoxysilane (TMOS) and mercaptopropyl trimethoxysilane (MPTMS). The samples have an ordered two-dimensional hexagonal pore array similar to that of MCM-41 as depicted from the XRD patterns. Nitrogen adsorption also shows that both microporous and mesoporous silica have pore characteristics similar to MCM-41, i.e. high surface area and high pore volume. However, pore regularity, surface area and pore volume decreased as the MPTMS loading increased. Solid-state ²⁹Si NMR indicated that the sulfo groups were successfully incorporated into both microporous and mesoporous silica frameworks. This sulfo-functionalized porous silica have high NH₃ uptakes and high differential heats of NH₃ adsorption, suggesting the presence of strong acidic sulfo groups on the silica surface. Acid catalyses of the samples were characterized by the isomerization reaction of but-1-ene to cis, trans-but-2-ene.     

Conversion of Malaysian low-rank coal to mesoporous activated carbon: Structure characterization and adsorption properties

Malaysian Selantik low-rank coal (SC) was used as a precursor to prepare a form of mesoporous activated carbon (SC-AC) with greater surface area (SA) via a microwave induced KOH-activation method. The characteristics of the SC and SC-AC were evaluated by the iodine number, ash content, bulk density, and moisture content. The structure and surface characterization was carried out using pore structure analysis (BET), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), elemental analysis (CHNS), thermogravimetric analysis (TGA), and determination of the point of zero charge (pH_PZC). These results signify a mesoporous structure of SC-AC with an increase of ca. 1160 times (BET SA=1094.3 m²·g^-1) as compared with raw SC without activation (BET SA=1.23 m²·g^-1). The adsorptive properties of the SC-AC with methylene blue (MB) was carried out at variable adsorbent dose (0.2-1.6 g·L^-1), solution pH (2-12), initial MB concentrations (25-400 mg·L^-1), and contact time (0-290 min) using batch mode operation. The kinetic profiles follow pseudo-second order kinetics and the equilibrium uptake of MB conforms to the Langmuir model with a maximum monolayer adsorption capacity of 491.7 mg·g^-1 at 303 K. Thermodynamic functions revealed a spontaneous endothermic adsorption process. The mechanism of adsorption included mainly electrostatic attractions, hydrogen bonding interaction, and π-π stacking interaction. This work shows that Malaysian Selantik low-rank coal is a promising precursor for the production of low-cost and efficient mesoporous activated carbon with substantive surface area.     

中间相沥青基泡沫炭的研究及应用

中间相沥青基泡沫炭具有低密度、高强度、高导热、抗冲击、耐高温、抗氧化等诸多特点,因而具有广泛的应用前景.目前,中间相沥青基泡沫炭最常用的制备方法是自发泡法.本文详细综述了中间相沥青基泡沫炭制备过程中的影响因素,也概述了近几年来国内外对泡沫炭的改性研究及应用.     

活性炭纤维的改性及对苯酚的吸附性能研究

用硫酸铜、高锰酸钾、硫酸亚铁、氢氧化钾、柠檬酸、硝酸铜、乙酸铅、硝酸等溶液浸渍处理活性炭纤维,考察了改性活性炭纤维对废水中苯酚的吸附性能。结果表明,用硫酸铜溶液改性的活性炭纤维对苯酚的吸附性能强于未改性的活性炭纤维,经高锰酸钾、硫酸亚铁、氢氧化钾、柠檬酸、硝酸铜、乙酸铅、硝酸等溶液改性的活性炭纤维对苯酚的吸附能力下降。浓度为0.05%~1%的硫酸铜溶液对0.2 g活性炭纤维进行改性的效果优于其它浓度的硫酸铜溶液。活性炭纤维上负载的铜离子过多会降低活性炭纤维对苯酚的吸附量。     

Synthesis of polyelectrolyte-modified ordered nanoporous carbon for removal of aromatic organic acids from purified terephthalic acid wastewater

In this work polyelectrolyte (polydiallyldimethylammonium chloride) modified ordered mesoporous carbon (CMK-1/PDDA) has been synthesized and has been employed in removal of major aromatic compounds present in purified terephthalic acid wastewater, such as p-toluic acid, benzoic acid, 4-carboxybenzaldehyde, phthalic acid and terephthalic. The adsorption behavior of these acidic impurities has been studied through batch experiments and using UV-spectrophotometric technique. The results show that CMK-1/PDDA is very effective in selective removal of acidic compounds from PTA-waste aqueous solutions. The electrostatic interaction was considered to be the main mechanism for the adsorption of acidic compounds. The effects of chemical modification, contact time, initial concentrations, adsorbent dose, agitation speed, solution pH and reaction temperature have been optimized. The sorption equilibrium was reached within 5 min. The sorption of acidic compounds on the CMK-1/PDDA slightly decreases with increasing pH, and temperature, indicating an exothermic process. The experimental isotherm data were analyzed using the Langmuir and Freundlich equations. The equilibrium data were best represented by the Langmuir isotherm.     

The influence of carbon source on the wall structure of ordered mesoporous carbons

A series of ordered mesoporous carbons (OMCs) have been synthesized by filling the pores of siliceous SBA-15 hard template with various carbon precursors including sucrose, furfuryl alcohol, naphthalene and anthracene, followed by carbonization and silica dissolution. The carbon replicas have been characterized by powder XRD, TEM and N₂ adsorption techniques. Their electrochemical performance used as electric double-layer capacitors (EDLCs) were also conducted with cyclic voltammetry and charge-discharge cycling tests. The results show that highly ordered 2D hexagonal mesostructures were replicated by using all these four carbon sources under the optimal operation conditions. Physical properties such as mesoscopic ordering, surface areas, pore volumes, graphitic degrees, and functional groups are related to the precursors, but pore sizes are shown minor relationship with them. The sources, which display high yields to carbons, for example, furfuryl alcohol and anthracene are favorable to construct highly ordered mesostructures even at high temperatures (1300 °C). OMCs prepared from non-graphitizable sources such as sucrose and furfuryl alcohol display amorphous pore walls, and large surface areas and pore volumes. The functional groups in the precursors like sucrose and furfuryl alcohol can be preserved on carbon surfaces after the carbonization at low temperatures but would be removed at high temperatures. The graphitizable precursors with nearly parallel blocks and weak cross-linkage between them like anthracene are suitable for deriving the OMCs with graphitic walls. Therefore, the OMCs originated from sucrose and furfuryl alcohol behave the highest capacitances at a carbonization of 700 °C among the four carbons due to the high surface areas and plenty of functional groups, and a declination at high temperatures possibly attribute to the depletion of functional groups. Anthracene derived OMCs has the lowest capacitance carbonized at 700 °C, and a steady enhancement when heated at high temperatures, which is attributed to the graphitization. The OMCs derived from naphthalene have the stable properties such as relatively high surface areas, few electroactive groups and limited graphitizable properties, and in turn medium but almost constant capacitances.     

新型介孔碳的制备及对罗丹明B的吸附动力学研究

采用SBA-15氧化硅分子筛为模板制备有序介孔碳CMK-3,研究了CMK-3作为吸附剂在水溶液中对罗丹明B的吸附作用,同时研究了初始浓度、pH和温度对吸附的影响.结果表明随着初始浓度的增大、pH增加和温度升高,吸附量增大,但是在较低的pH下,吸附量增加的较小,当pH较高时,吸附量增加的较多.分别采用拟一级反应和拟二级反应模型考察了吸附动力学,并计算了这些动力学模型的速率常数.拟二级反应模型和实验数据之间有较好的相关性.     

Immobilization of uranium in cristobalite ceramic through adsorption on mesoporous SBA-15 and further sintering process

The development of an adsorbent which can be easily transformed into stable ceramic waste forms through a simple route is necessary for the treatment of the radioactive wastewater. Herein, we report on the immobilization of uranium in cristobalite ceramic through adsorption on mesoporous SBA-15 and further sintering process. The mesoporous SBA-15 with short pore length was synthesized and employed to remove uranium from aqueous solution. Subsequently, the SBA-15 with adsorbed U (U/SBA-15) was solidified by sintering. The effects of sintering temperature and U content on the structure, densification and aqueous durability of the obtained cristobalite ceramic waste forms were investigated. The results indicate that the U/SBA-15 can be transformed into stable cristobalite ceramic after sintering at 1100–1400 °C for 6 h. Furthermore, all the obtained cristobalite ceramic waste forms exhibit good aqueous durability (∼10⁻⁴ g m^-2 d^-1). This work demonstrates a potential route and adsorbent to dispose the radioactive wastewater.     

有序介孔碳和活性炭对阿莫西林的吸附研究

阿莫西林是废水中一类典型的药品与个人护理品类新型有机污染物,会对周围环境和人体健康造成潜在威胁。以蔗糖为碳源、以SBA-15为模板制备有序介孔碳（OMC）。采用动态吸附法研究其对阿莫西林的吸附行为,并与常规吸附材料商用活性炭（GAC）作对比。探讨了废水中阿莫西林的初始浓度、温度及流速对动态吸附的影响。结果表明：在同等条件下,OMC的吸附能力远强于GAC,以OMC为吸附剂可有效去除废水中的阿莫西林类新型有机污染物。     

Methane sorption on ordered mesoporous carbon in the presence of water

An ordered mesoporous carbon was synthesized using SBA-15 as the template. The sorption isotherms of methane on the synthesized carbon material were collected. Its ordered structure was confirmed by the XRD, SEM and TEM examinations. The BET surface area is 1100-1200 m²/g, the total pore volume is 1.24-1.30 cm³/g, and the pore size distribution is very narrow and centered at 2-5 nm. As high as 41.2 wt.% of methane was stored per unit mass of carbon at 275 K and pressures less than 7 MPa in the presence of 3.86 times more water. This sorption amount is 31% higher than the largest sorption capacity reached by activated carbon in the presence of water, which was equal to or higher than the storage capacity of compression till 20 MPa. The enthalpy change corresponding to the sudden change of isotherms was equal to the enthalpy change of methane hydrate formation; therefore, the mechanism of the enhanced methane storage was considered due to the formation of methane hydrate in the porous carbon material.     

Efficient adsorption and in-situ ceramics immobilization of simulated trivalent actinides (Nd) by amino-functionalized mesoporous zirconia-silica

It is of great significance to develop a kind of adsorbent which can adsorb and in-situ immobilize radionuclides from aqueous solution. Herein, new amino-functionalized mesoporous zirconia-silica (ZNSi) composites were prepared and applied to adsorb and in-situ immobilize the simulated trivalent actinides (Nd) from aqueous solution. The obtained ZNSi composites exhibited high Nd adsorption capacity (31.14 mg/g) owing to the formation of Nd(OH)₃ via the reaction between Nd³⁺ and OH⁻ derived from the protonation of amino groups. The spent adsorbents with adsorbed Nd³⁺ were successfully changed to stable ZrSiO₄-based glass ceramics by simple sintering treatment. The ZrO₂ and Nd contents had great effect on the phase composition, microstructure evolution and aqueous stability of the obtained ZrSiO₄-based glass ceramics waste forms. The immobilized Nd showed excellent aqueous stability (10⁻⁷ g m⁻² d⁻¹) due to the crystal lattice immobilization of ZrSiO₄. Owing to the efficient adsorption and in-situ immobilization ability, the obtained ZNSi could be potential materials for radioactive wastewater treatment.