Template-free synthesis of MgO mesoporous nanofibers with superior adsorption for fluoride and Congo red

MgO mesoporous nanofibers were obtained by a template-free electrospinning method. The unique bumpy-structure was obtained on the surface of nanofibers that could enhance the surface area and provide more active sites for adsorption. The formation mechanism of the bumpy-structure has been investigated. The as-prepared MgO nanofibers with a high surface area of 194.17?m² g^?1 exhibited excellent adsorption capacities for fluoride of 237.49?mg?g^?1. Furthermore, the MgO nanofibers showed selective adsorption for different organic dyes and have superior adsorption capacity for Congo red (4802.27?mg?g^?1). The adsorption processes for both fluoride and Congo red were systematically investigated, which were found to follow the pseudo-second-order kinetic model. By comparison with the reported fabrication routes and adsorption capacities of mesoporous MgO, the synthesis process is simple, controllable and template-free, and the superior adsorption performance provided a potential adsorbent for the removal of fluoride and Congo red in wastewater treatment. The high surface area of the MgO mesoporous nanofibers might also promote its application in basic catalysis and other fields.     

A wormhole-structured mesoporous carbon with superior adsorption for dyes

A series of large-pore mesoporous carbon materials with a three-dimensional wormhole framework structure were synthesized by nanocasting using mesoporous silica as a hard template. Samples of hard-template mesoporous silica with pore diameters from 3.08 to 6.43 nm, pore volumes from 0.59 to 1.02 cm³ g⁻¹ and surface areas from 832 to 579 m² g⁻¹ were prepared from tetraethyl orthosilicate as the silica source and ionic liquid 1-butyl-3-methylimidazolium bromide as structure-directing agent through hydrothermal treatment at different temperatures (110–150 °C) followed by calcining at 550 °C. Subsequently, carbon materials with large pore diameters (2.76–6.70 nm), pore volumes (0.74–2.10 cm³ g⁻¹) and high surface areas (1074–1276 m² g⁻¹) were synthesized using the various mesoporous silicas synthesized at the different hydrothermal temperatures as a hard-template. The carbon material obtained at a hydrothermal temperature of 150 °C possesses outstanding adsorbility for amaranth and methylene blue dyes.     

新型介孔有机聚合物对氢气存储和染料快速吸附研究

采用二甲氧基甲烷对四苯基硼酸钠进行Friedel-Craft烷基化,得到了一种具有阴离子骨架的介孔材料MPTB-1。借助气体吸附仪和紫外分光光度计对该材料氢气存储性能和常见有机染料分子的吸附性能进行研究。结果表明,材料孔径分布在5.3 nm附近,属于介孔材料;在分压0.1 MPa时可以吸附1.19%(质量分数)的氢气;该材料对阳离子染料罗丹明B具有较高的吸附效率,对水中染料去除率30 min可达99%以上;MPTB-1对罗丹明B的吸附等温线符合Langmuir模型,吸附动力学符合准二级动力学模型。表明材料对罗丹明B的吸附为均匀的单分子层吸附,而且两者之间存在化学吸附作用。     

Magnetic mesoporous iron oxide/silica composite aerogels with high adsorption ability for organic pollutant removal

In this paper, a kind of magnetic mesoporous iron oxide/silica composite aerogels with high adsorption ability is prepared by ambient pressure drying method. The results indicate that the obtained magnetic aerogels with Fe/Si (molar ratio) >0.91 % have higher specific surface area with 310.8–411.0 m² g^?1 and pore volume with 0.85–1.12 cm³ g^?1. The adsorption test indicates that the obtained magnetic aerogels showed prominent adsorption capability with the adsorption rate for Rhodamine B in aqueous solution could attain to 95.8 % within 80 min. Moreover, all the composite aerogels exhibited good magnetic properties and could be easily separated from the water after adsorption.     

One-step synthesis of bimetallic Pt-Pd/MCM-41 mesoporous materials with superior catalytic performance for toluene oxidation

The catalytic performances of Pt-Pd/MCM-41 bimetallic catalysts prepared by one-step synthesis method were investigated for total toluene oxidation in this paper. The experimental results demonstrated that Pt-Pd/MCM-41 was of superior catalytic activity comparing to the monometallic Pt/MCM-41 or Pd/MCM-41 catalysts with the same metallic content, yielding an almost 100% conversion at 180 °C. The following characterization results indicated that the bimetallic catalyst possessed a higher surface Pt(0) content and smaller doped metal size owing to the synergistic effect of the two noble metals, resulting in the improvement of oxygen adsorption capacity and the reducibility.     

Facile synthesis and superior ethyl acetate sensing performance of Au decorated ZnO flower-like architectures

Au decorated ZnO flower-like architectures assembled from single crystal nanowires have been successfully synthesized. A facile thermal treatment route was employed, utilizing the composite gel of zinc acetate and polyvinyl pyrrolidone (PVP) as raw materials and was followed by a subsequent Au reduction process. PVP served as a surfactant and played a critical role in the generation of crystalline nanowires as well as for the formation of ZnO flower-like structure. Based on control experiments, the growth mechanism of ZnO flower-like structures was proposed. The diameter of ZnO crystalline nanowires was approximately 50–80 nm and the size of Au particles deposited on the surface of ZnO nanowires was approximately 5 nm. When tested as gas sensing material, the as-prepared Au decorated ZnO flower-like architecture exhibited superior gas sensing performance compared to ethyl acetate in terms of high response (approximately 102 at 100 ppm), short response and recovery times (10 s and 13 s, respectively), and low operating temperature (240 °C). The superior gas sensing performances are mainly attributed to the synergistic effects of ZnO crystalline nanowires and Au nanoparticles, as well as to the flower-like structure.     

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.     

Adsorption performance of mesoporous silicas towards a cationic dye. Influence of mesostructure on adsorption capacity

The dye adsorption performance of four mesoporous silicas with different structure and textural properties, MCM-41, MCM-48, SBA-15 and mesocellular silica foam (MCF), was studied and compared by using toluidine blue O (TBO) as dye model in aqueous solution. These materials were characterized by X-ray diffraction (XRD), small-angle X-ray scattering, nitrogen adsorption-desorption analyses, and transmission electron microscopy (TEM). The effect of some parameters such as adsorbent dosage, contact time, temperature, and pH on the TBO removal in aqueous solution was studied. Results showed that adsorption capacity raised when adsorbent dosage, contact time and pH solution were increased while an increase in temperature decreased the adsorption of TBO. Langmuir, Freundlich and Temkin isotherm models were employed to elucidate the adsorption mechanism while the adsorption rate data were analyzed according to the pseudo-first and second-order kinetic models. Results showed that adsorption of TBO onto MCM-48, SBA-15, and MCF fitted well the Freundlich isotherm model while the kinetic studies showed that adsorption process could be better described by the pseudo-second-order model for all mesoporous silicas. Finally, some solvents were evaluated to carried out dye desorption from the TBO-loaded mesoporous silicas founding that acetic acid was the most efficient.     

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.     

介孔及介观结构材料掺杂有机染料的研究进展

从材料制备方法的角度出发,对近年来介孔及介观结构材料掺杂有机染料的光学性能研究进行了综述,比较分析了各种制备方法的优缺点,对其在光学各领域的应用前景作了展望。     

介孔氧化锰对甲醛的低温催化氧化

采用硬模板法合成了介孔氧化锰纳米材料,考察了甲醛浓度对甲醛的催化氧化活性的影响。通过X射线衍射(XRD)、透射电镜(TEM)、高分辨透射电镜(HRTEM)等分析手段对合成的介孔材料进行了表征。结果显示,所合成的氧化锰具有很好的有序三维介孔结构,对甲醛具有优异的催化性能。甲醛的初始浓度对催化剂的活性有很大的影响,随着初始浓度的降低,催化剂活性逐渐提高。当甲醛的初始浓度为30 mg/L时,氧化锰催化剂在40℃时即可将甲醛完全降解。对于非贵金属型甲醛降解催化剂,此温度属于较低的。氧化锰优异的催化活性可能与其有序的介孔结构有很大的关系。     

介孔氧化锰对甲醛的低温催化氧化

采用硬模板法合成了介孔氧化锰纳米材料,考察了甲醛浓度对甲醛的催化氧化活性的影响。通过X射线衍射(XRD)、透射电镜(TEM)、高分辨透射电镜(HRTEM)等分析手段对合成的介孔材料进行了表征。结果显示,所合成的氧化锰具有很好的有序三维介孔结构,对甲醛具有优异的催化性能。甲醛的初始浓度对催化剂的活性有很大的影响,随着初始浓度的降低,催化剂活性逐渐提高。当甲醛的初始浓度为30 mg/L时,氧化锰催化剂在40℃时即可将甲醛完全降解。对于非贵金属型甲醛降解催化剂,此温度属于较低的。氧化锰优异的催化活性可能与其有序的介孔结构有很大的关系。     

Hydrothermal synthesis of mesoporous carbons for adsorption of two alkaloids

Two mesoporous carbons were synthesized via a hydrothermal treatment approach, characterized and evaluated for adsorption properties of berberine hydrochloride and matrine from water. The mesoporous carbons have BET specific surface areas of 1568.1 and 769.3 m²/g, pore volumes of 1.44 and 0.89 cm³/g, average pore diameters of 3.75 and 8.22 nm, and few O-containing functional groups on the surfaces. Both the mesoporous carbon adsorbents can effectively adsorb berberine hydrochloride and matrine from aqueous solutions, the higher equilibrium adsorption capacities of berberine hydrochloride and matrine at 298 K are 385, and 275 mg/g at 0.10 mg/mL, respectively. Adsorption enthalpy, entropy and free energy of berberine hydrochloride and matrine on the selected mesoporous carbon (with higher BET specific surface area and pore volume) were calculated. The adsorption of berberine hydrochloride and matrine on the selected carbon sample is fast at 298 K, 95% of the adsorption equilibrium could be achieved within 180 and 120 min, respectively. The dynamic adsorption capacities on the selected adsorbent are calculated to be 343.1 and 383.4 mg/g for berberine hydrochloride and matrine, respectively; and 70.8% of the adsorbed berberine hydrochloride and 79.2% of the adsorbed matrine could be desorbed by a 70% alcohol solution. These results provide a reference to the large-scale industrial production and application of mesoporous carbons as potential adsorbents in purification of alkaloids from herbal plant extracts.     

Direct synthesis and superior catalytic performance of V-containing SBA-15 mesoporous materials for oxidative dehydrogenation of propane

V-containing SBA-15 mesoporous materials have been directly synthesized in an acidic and peroxidic medium. Compared to V/SBA-15 and V/SiO₂ samples prepared by impregnation method, the materials thus synthesized show larger surface areas, higher dispersion and reducibility of VO _x species, and superior catalytic performance for oxidative dehydrogenation of propane.     

氨改性的介孔二氧化硅的直接合成和CO2吸附

Amine-functionalized mesoporous silica was prepared by using lauric acid and N-stearoyl-l-glutamic acid as structure directing agents via the SN+-I mechanism and applied to CO2 adsorption at room temperature. With γ-aminopropyltriethoxysilane as co-structure directing agent and due to the direct electrostatic interaction with anionic surfactant, most of the amino groups were uniformly distributed at the inner surface of pores and the performance was stable. The amine-functionalized mesoporous silica was characterized by Fourier transform infrared spectrometer, X-ray diffraction, nitrogen physisorption and thermogravimetric analysis. The CO2 adsorption capacity was measured by digital recording balance. At the room temperature and under the atmospheric pres-sure, the adsorption capacity of LAA-AMS-0.2 for CO2 and N2 is 1.40 mmol•g1 and 0.03 mmol•g1, respectively, indicating high separation coefficient of CO2/N2.     

Hydrous-ferric oxide nanorods grown on PEGylated graphene oxide with superior capacity for selective adsorption of albumin

A ferrate functionalized graphene-based composite is prepared by growth of hydrous ferric oxide (FeOOH) on the polyethylene glycol (PEG) modified graphene oxide (GO) sheets. The obtained GO–PEG–FeOOH composite is characterized by ATR-FTIR, TEM, AFM, XPS and ICP-MS. The PEGylation significantly changes the surface property of the bare graphene oxide, which not only generates a nano-bio-interface for protein interaction but also reduces the non-specific adsorption of proteins. The PEGylation and growth of FeOOH nanorods on GO sheets obviously enhanced the selectivity toward the adsorption of albumin through strong hydrogen bonding interaction, exhibiting an ultra-high adsorption capacity of 1377.4 mg g⁻¹ for bovine serum albumin (BSA). It is obviously higher than those achieved by any hitherto reported graphene based materials and other carbon nanomaterials. Albumin retained by the composite could be effectively recovered with a 4.0 mM B–R buffer through the affinity of boronic acid toward protein, giving rise to a recovery of 70%. Circular dichroism (CD) spectra indicate no conformational change for BSA during the process of adsorption/desorption. The practical applicability of the GO nanocomposite is further demonstrated by the selective adsorption/isolation of albumin from complex biological samples matrixes, e.g., human whole blood.     

Preparation of manganese monoxide@reduced graphene oxide nanocomposites with superior electrochemical performances for lithium-ion batteries

Manganese monoxide (MnO) nanowire@reduced graphene oxide (rGO) nanocomposites are synthesized using a simple hydrothermal method combined with a calcination process. The structural and morphological characterization of the composites indicates that the MnO nanowires homogeneously anchor on both sides of the cross-linked rGO. The nanocomposites exhibit a high surface area of 126.5?m² g^?1. When employed as an anode material for lithium-ion batteries, the nanocomposites exhibit a reversible capacity of 1195 mAh g^?1 at a current density of 0.1?A?g^?1, with a high charge-discharge efficiency of 99.2% after 150 cycles. The three-dimensional architecture of the present materials exhibits high porosity and electron conductivity, significantly shortening the diffusion path of lithium ions and accelerating their reaction with the electrolyte, which greatly improves the lithium-ion storage properties. These excellent electrochemical performances make the composite a promising electrode material for lithium-ion batteries.     

Synthesis of ordered mesoporous manganese titanium composite oxide catalyst for catalytic ozonation

In this account, highly ordered mesoporous MnO_x/TiO₂ composite catalysts with efficient catalytic ozonation of phenol degradation were synthesized by the sol–gel method. The surface morphology and properties of the catalysts were characterized by several analytical methods, including SEM, TEM, BET, XRD, FTIR, and XPS. Interestingly, Mn doping was found to improve the degree of order, and the ordered mesoporous structure was optimized at 3% doping. Meanwhile, MnO_x was highly dispersed in the ordered mesoporous materials to yield good catalytic ozonation performance. Phenol could completely be degraded in 20 min and mineralized at 79% in 60 min. Thus, the catalyst greatly improved the efficiency of degradation and mineralization of phenol when compared to single O₃ or O₃ + TiO₂. Finally, the reaction mechanism of the catalyst was discussed and found to conform to pseudo-first-order reaction dynamics.     

Radiation synthesis of graphene oxide/composite hydrogels and their ability for potential dye adsorption from wastewater

A high yield of graphene oxide (GO) was chemically synthesized from graphite powder utilizing adjusted Hummer's method. The contents of acidic functional groups in GO were determined using potentiometric titration. Composite hydrogels dependent on graphene oxide/poly(2-acrylamido-2-methylpropanesulfonic acid)/polyvinyl alcohol (GO/PAMPS/PVA) were synthesized utilizing a ⁶⁰Co gamma irradiation source at different doses. The synthesized graphene oxide and composite hydrogels were portrayed via X-ray diffraction, thermogravimetric analysis, and Fourier transform infrared analysis. The morphology of composite hydrogels was characterized by scanning electron microscope. The gel % and swelling % for the prepared hydrogel demonstrated that the swelling % of hydrogel increased with raising AMPS content. Whereas the increment of GO and increasing the irradiation dose lead to a reduction in the swelling %. The influences of pH, GO percentage, initial dye concentration, the adsorbent dosage, contact time, and temperature on the adsorption of basic blue 3 dye were evaluated and the adsorption capacity was 194.6 mg/g at optimum conditions; pH = 6, GO/PAMPS/PVA composite hydrogels with 5 wt% of GO, initial dye concentration = 200 mg/L, adsorbent dose = 0.1 g, solution volume = 50 mL after 360 min at room temperature (25°C). The adsorption of dye onto the GO/PAMPS/PVA composite hydrogels follows Pseudo-second-order adsorption kinetics, fits the Freundlich adsorption isotherm model.