Synthesis of benzxazine-based nitrogen-doped mesoporous carbon spheres for methyl orange dye adsorption

In this work, nitrogen-doped mesoporous carbon spheres (NMCS) were synthesized through a hard template method by using benzoxazine resin as precursor and ordered mesoporous silica spheres as template. The obtained N-doped mesoporous carbons were amorphous spherical nanoparticles with worm-like mesoporous channels and possessed high surface area of 789 m²/g, large pore volume of 0.49 cm³/g and high nitrogen content of 3.50 wt.%. The adsorption capacity of methyl orange (MO) by NMCS could attain 352.1 mg/g at an optimal condition, while the adsorption capacity of MO by non-doped mesoporous carbon spheres (MCS) was 251.9 mg/g at the same condition. The adsorption process fitted the pseudo-second-order kinetic model and the Langmuir isotherm well. Thermodynamic analysis indicated that the removal of MO by NMCS was spontaneous, endothermic and feasible process. In addition, the adsorption capacity of regenerated adsorbent was 89.04% of the initial level after four regeneration cycles.     

Synthesis and characterization of mesoporous carbon through inexpensive mesoporous silica as template

Mesoporous silica materials have been synthesized through sol–gel reaction using inexpensive sodium silicate as source of silica and low cost hydroxy carboxylic acid compounds as templates/pore forming agents. The material measured surface area of 1014 m²/g, pore diameter of 65 Å and pore volume of 1.4 cc/g when parameters like time and temperature of synthesis along with mole ratio of TA/SiO₂ were optimized. Here TA stands for tartaric acid. Carbonization of sucrose inside the pores of above silica material at 900 °C followed by removal of silica framework using aqueous ethanoic solution of NaOH gave rise to mesoporous carbon material. The resulting materials were characterized by N₂-sorption, FTIR spectroscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, thermal analysis and cyclic voltammetry. Three dimensional interconnecting wormhole channel arrangement of mesoporous silica template leads to mesoporous carbon replica with surface area of 1200 m²/g. X-ray photoelectron spectroscopic study (XPS) of the mesoporous carbon material shows the concentration of carbon atom in the range of 97–98% with 1–2% oxygen and negligible amount of silica. The electrochemical double layer capacitance behavior of carbon material with the specific capacitance value of 88.0 F/g at the scan rate of 1 mV/s appears to be promising.     

以蔗糖为模板剂合成介孔氧化铝

以蔗糖为模板剂,异丙醇铝为铝源,水相体系下,考察了体系pH和模板剂用量对介孔氧化铝合成的影响。并采用X射线衍射、透射电镜(TEM)、氮吸脱附以及固体核磁等手段对合成样品进行表征。结果表明,合成的介孔氧化铝为γ-Al2O3,具有较高的比表面积以及较集中的孔径分布。体系的pH和模板剂用量对介孔氧化铝产物的性能有一定影响,并对蔗糖的模板作用机理进行了讨论。     

Synthesis of an ordered mesoporous carbon with graphitic characteristics and its application for dye adsorption

An ordered mesoporous carbon (OMC) was prepared by a chemical vapor deposition technique using liquid petroleum gas (LPG) as the carbon source. During synthesis, LPG was effectively adsorbed in the ordered mesopores of SBA-15 silica and converted to a graphitic carbon at 800 °C. X-ray diffraction and nitrogen adsorption/desorption data and high-resolution transmission electron microscopy (HRTEM) of the OMC confirmed its ordered mesoporous structure. The OMC was utilized as an adsorbent in the removal of dyes from aqueous solution. A commercial powder activated carbon (AC) was also investigated to obtain comparative data. The efficiency of the OMC for dye adsorption was tested using acidic dye acid orange 8 (AO8) and basic dyes methylene blue (MB) and rhodamine B (RB). The results show that adsorption was affected by the molecular size of the dye, the textural properties of carbon adsorbent and surface-dye interactions. The adsorption capacities of the OMC for acid orange 8 (AO8), methylene blue (MB) and rhodamine B (RB) were determined to be 222, 833, and 233 mg/g, respectively. The adsorption capacities of the AC for AO8, MB, and RB were determined to be 141, 313, and 185 mg/g, respectively. The OMC demonstrated to be an excellent adsorbent for the removal of MB from wastewater.     

以离子液体为模板剂合成MCM-41介孔分子筛

以离子液体1-十六烷基-3-甲基溴代咪唑为模板剂,合成介孔分子筛MCM-41。考察了不同硅源[、C16mim]Br/SiO2配比、pH值、晶化时间等条件对合成MCM-41的影响。采用XRD和低温氮吸附对产物进行表征,结果表明该方法合成的样品具有较大比表面积和规整介孔孔道结构。     

Easy synthesis of mesoporous carbon using nano-CaCO3 as template

Mesoporous carbon has been synthesized using nano-CaCO₃ as a template and sucrose as carbon precursor. It is shown that the CaCO₃/sucrose weight ratio has a marked effect on the porosity of the carbon. At a weight ratio of CaCO₃/sucrose of 1:1, the surface area of the carbon reaches 892 m² g⁻¹ and the pore size is around 45 nm. The carbon shows a capacitance of 155 F/g with excellent rate capability in 6 mol L⁻¹ KOH aqueous electrolytes.     

Synthesis of bimodal mesoporous carbon nanospheres for methyl orange adsorption

Mesoporous materials with bimodal mesopores show advantages in adsorption, energy storage, and catalysis because such unique structures are beneficial to the mass transfer. Here, we describe the synthesis of bimodal mesoporous carbon nanospheres (BMCSs) by using phenolic resin as carbon precursor, triblock copolymer Pluronic F127 as the soft template, and mesoporous silica spheres as hard templates. The BMCSs with uniform spherical morphology, high specific surface area (1489 m² g^??1), large pore volume (0.92 cm³ g^??1), and bimodal mesoporous structure (3.8 and 6.8 nm) exhibit promising properties for adsorption of methyl orange (MO). The maximum adsorption capacity of the BMCSs is 5.5?×?10² ± 0.2?×?10² mg g^??1, which is higher than that of many adsorbents reported. The kinetics studies show a better fit of pseudo-second-order model. Meanwhile, fitting equilibrium data show that the Langmuir model is more suitable to describe the MO adsorption than Freundlich model.     

Synthesis of mesoporous molecular sieves as catalytic template for the growth of single walled carbon nanotubes

Mesoporous Mo MCM-41 and Nb MCM-41 molecular sieves were synthesized in various ratios by hydrothermal method and were characterized by XRD, N₂ adsorption isotherm and DRS-UV spectroscopy. The calcined samples were used as catalysts for the growth of carbon nanotubes using acetylene by chemical vapor deposition technique at 700–900 °C. The deposited carbon materials by acetylene decomposition, were found to be more in the case of Nb MCM-41 than in Mo MCM-41, and their catalytic activity was found to be in the order as Si/Nb = 100 > 75 > 50 > 25, and the same trend is followed for Mo MCM-41 molecular sieves. The catalytically synthesised carbon materials were characterized with Raman spectroscopy, SEM and TEM. We have obtained single walled carbon nanotubes in bundles with a tube diameter of 1.06–2.9 nm and 1.08–2.3 nm formed over Mo MCM-41 and Nb MCM-41, respectively, according to Raman spectra. Similarly well graphitised single walled carbon nanotubes formation was observed from TEM. From this observation, it is confirmed that Mo MCM-41 (100) and Nb MCM-41 (100) exist as stable catalysts for the synthesis of single walled nanotube.     

Synthesis of ordered cerium-doped cubic mesoporous silica using long-chain ionic liquid as template

The long-chain ionic liquid 1-hexadecyl-3-methylimidazolium chloride (C₁₆mimCl) was used as a template to prepare cerium-doped MCM-48 materials in basic medium by a hydrothermal synthesis procedure. The effect of the amount of Ce salt and C₁₆mimCl/Si on the synthesis were discussed in detail. This mesoporous material exhibits a pore architecture which is cubic Ia3d gyroid and possesses a large surface area and a narrow pore distribution. Cerium in calcined porous framework exists in the form of well-dispersed tetrahedral coordination. The C₁₆mimCl shows a high tendency toward self-aggregation that allows the formation of the cerium-doped gyroid mesostructure by using the appropriate amount of Ce salt.     

Synthesis of ordered cerium-doped cubic mesoporous silica using long-chain ionic liquid as template

The long-chain ionic liquid 1-hexadecyl-3-methylimidazolium chloride (C₁₆mimCl) was used as a template to prepare cerium-doped MCM-48 materials in basic medium by a hydrothermal synthesis procedure. The effect of the amount of Ce salt and C₁₆mimCl/Si on the synthesis were discussed in detail. This mesoporous material exhibits a pore architecture which is cubic Ia3d gyroid and possesses a large surface area and a narrow pore distribution. Cerium in calcined porous framework exists in the form of well-dispersed tetrahedral coordination. The C₁₆mimCl shows a high tendency toward self-aggregation that allows the formation of the cerium-doped gyroid mesostructure by using the appropriate amount of Ce salt.     

Synthesis of mesoporous alumina by using a cost-effective template

A salt of stearic acid, i.e., magnesium stearate [(C₁₇H₃₅COO)₂Mg], can be used as a chemical template for the formation of mesoporous alumina, and is a less expensive reagent than stearic acid. Mesoporous alumina prepared using this cost-effective surfactant shows similar pore properties with respect to pore size (3.5 nm) and surface area (above 300 m²Vg) to that prepared using stearic acid. In addition, textural porosity, arising from non-crystalline intraaggregate voids and spaces, was effectively removed by the addition of magnesium nitrate. The entire transformation from aluminum hydroxide to active alumina was performed at 550 °C, and the crystallinity of the product was confirmed by powder XRD analysis.²⁷A1 MAS NMR result shows the phase of mesoporous alumina is the γ-alumina form.     

Synthesis of hydroxyapatite nanoparticles using surface carboxyl-functionalized carbon dots as template

Carbon dots (CDs), which are discrete, nearly spherical nanoparticles with sizes below 10?nm and large amounts of carboxylic acid moieties on the surface, have been proposed as an ideal template candidate for heterogeneous nucleators to regulate hydroxyapatite (HAp) nucleation and growth. In this paper, small HAp nanoparticles formed on carboxyl-functionalized CDs in situ were fabricated via the hydrothermal method. Investigation for the corresponding morphologies and detailed formation mechanisms of samples were conducted by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM) and Rietveld refinement. The optimum size and crystallinity of HAp particle had been obtained in the preparation when the additive content of CDs was 1.11?g/L. Moreover, results also suggested that CDs were served as nucleators in the HAp particles. Therefore, a novel synthetic strategy is presented for small HAp nanoparticles using CDs as template.     

Synthesis of mesoporous carbon and its adsorption property to biomolecules

Mesoporous carbon (MC) with high surface area and large pore volume was synthesized using mesophase pitch as a carbon precursor and nanosized MgO as an additive. The maximum surface area, largest pore volume and highest mesoporous ratio of as-prepared MC were up to 1400 m²/g, 2.8 cm³/g and 89%, respectively. The mesoporous structures (3–40 nm) of MC were directly observed under SEM and TEM. The adsorption capacity and adsorption rate of MC to vitamin B₁₂ (VB), chicken egg white albumin (CEWA) and bovine serum albumin (BSA) were proportional to the mesopore volume and average pore size. MC (PM4-OC) exhibited the maximum adsorption capacity to the typical biomolecules, 486, 140 and 176 mg/g for VB, CEWA and BSA, respectively. In contrast, Maxsorbs (commercial activated carbons) with a surprising surface area gave a very low adsorption to such biomolecules. The research indicates that MC may be potential in the selective adsorption and separation of biomolecules, based on a molecule sieve effect.     

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.     

Synthesis and characterization of mesoporous electrospun carbon fibers derived from silica template

In our study, mesoporous carbon fibers were prepared by using electrospinning and physical activation. In order to develop mesoporous structure, silica was used as a physical activation agent due to meso-size of particle. The diameter of activated carbon fibers increased and surface became rougher after physical activation. Textural properties of carbon fibers were evaluated by using surface pore structure analysis apparatus. The specific surface area increased 12 times and total pore volume increased about 57 times through physical activation using silica. The development of mesoporous structure was confirmed by pore size distribution and fraction of micropore volume. From the DFT pore size distribution, it is sure that broad meso-sized porous carbon fibers were obtained from physical activation in our experiment. The fact that fractions of micropore volume are too low showing less than 2% by the results of total pore volume and HK pore volume concedes that silica activated CFs are pretty mesoporous. Eventually activated carbon fibers having broad meso-sized pores were obtained successfully.     

Synthesis and characterization of mesoporous graphite carbon,and adsorption performance for benzene

In this paper, graphite carbon with a mesoporous structure was synthesized using the template–catalysis procedure with hydrated metal oxide nanoparticle as template and catalyst, phenol and formaldehyde as carbon source. XRD, Raman, BET and TEM analyses were performed to study the effluence of synthetic conditions on the structure of samples. The adsorption performances for benzene vapor were evaluated. The results show that CCo and CFe samples have mesoporous graphitized carbon structures. The molar amount of template to carbon source significantly affects the specific surface area, pore structure and adsorption–desorption performance. The specific surface area of CCo-1, with the best graphite structure, was 287.638 m²/g, the pore size was 19.075 nm, and the adsorption capacity for benzene vapor was 19.615 mmol/g. The synergistic effect between the cobalt element and graphite carbons affects the adsorption capacity of CCo-3, which was 34.643 mmol/g. However, the desorption efficiency was only 89 %, and the adsorption performance of CCo-3 material was degraded greatly after three times run.     

Textural property tuning of ordered mesoporous carbon obtained by glycerol conversion using SBA-15 silica as template

“Wet” and “dry” template methods were used to simultaneously control the pore size, morphology, and graphitization in structurally well-ordered mesoporous carbons. A novel structure has been prepared using glycerol as the carbon source. Depending on the loading amount of the glycerol, the structural characteristics of the mesoporous carbon materials can be controlled. The structurally well-ordered carbon materials have been characterized by various techniques such as nitrogen sorption, XRD, Raman spectroscopy, TGA measurements and SEM. They have graphitic character, high BET surface area (ca 1440 m²/g) and a tunable pore size. They are likely to be useful in a variety of applications including gas storage, electrode materials or catalyst supports.