An investigation is performed into the efficiency of the
Streptomyces griseus
HUT 6037 enzyme immobilized in three different mesoporous silicas, namely mesoporous silica film, mesocellular foam, and ...rod-like SBA-15. It is shown that for all three supports, the pH value changes the surface charge and charge density and hence determines the maximum loading capacity of the enzyme. The products of the enzyme hydrolytic reaction are analyzed by
1
H-NMR. The results show that among the three silica supports, the mesoporous silica film (with a channel length in the range of 60-100 nm) maximizes the accessibility of the immobilized enzyme. The loading capacity of the enzyme is up to 95% at pH 7 and the activity of the immobilized enzyme is maintained for more than 15 days when using a silica film support. The order of the activity of the enzyme immobilized in different mesoporous silica supports is: mesoporous silica film > mesocellular foam > rod-like SBA-15. Furthermore, the immobilized enzyme can be easily separated from the reaction solution
via
simple filtration or centrifugation methods and re-used for hydrolytic reaction as required.
Mesoporous silica films were used as supports with high loading capacity and enzyme activity.
Multiporous carbons (MPCs) are prepared using ZnO as a hard template and biomass pyrolysis oil as the carbon source. It is shown that the surface area, pore volume, and mesopore/micropore ratio of ...the as-prepared MPCs can be easily controlled by adjusting the ZnO/oil ratio. Sulfur/MPC (S/MPC) composite is prepared by blending sulfur powder with the as-prepared MPCs followed by microwave heating at three different powers (100 W/200 W/300 W) for 60 s. The unique micro/mesostructure characteristics of the resulting porous carbons not only endow the S/MPC composite with sufficient available space for sulfur storage, but also provide favorable and efficient channels for Li-ions/electrons transportation. When applied as the electrode material in a lithium-ion battery (LIB), the S/MPC composite shows a reversible capacity (about 500 mAh g
) and a high columbic efficiency (>95%) after 70 cycles. Overall, the method proposed in this study provides a simple and green approach for the rapid production of MPCs and S/MPC composite for high-performance LIBs.
Partially fermented tea such as oolong tea is a popular drink worldwide. Preventing fraud in partially fermented tea has become imperative to protect producers and consumers from possible economic ...losses. Visible/near-infrared (VIS/NIR) spectroscopy integrated with stepwise multiple linear regression (SMLR) and support vector machine (SVM) methods were used for origin discrimination of partially fermented tea from Vietnam, China, and different production areas in Taiwan using the full visible NIR wavelength range (400–2498 nm). The SMLR and SVM models achieved satisfactory results. Models using data from chemical constituents’ specific wavelength ranges exhibited a high correlation with the spectra of teas, and the SMLR analyses improved discrimination of the types and origins when performing SVM analyses. The SVM models’ identification accuracies regarding different production areas in Taiwan were effectively enhanced using a combination of the data within specific wavelength ranges of several constituents. The accuracy rates were 100% for the discrimination of types, origins, and production areas of tea in the calibration and prediction sets using the optimal SVM models integrated with the specific wavelength ranges of the constituents in tea. NIR could be an effective tool for rapid, nondestructive, and accurate inspection of types, origins, and production areas of teas.
In this study, one‐pot hydrothermal synthesis of sheet‐like ZSM‐5 as a high‐performance catalyst for toluene disproportionation was carried out using binary surfactants. In the dual template, ...tetraethylammonium hydroxide was used to construct the microporous structure of ZSM‐5, and cationic surfactant (e.g., octadecyltrimethylammonium chloride (C18TMAC), hexadecyltrimethyl ammonium bromide (C16TMAB), and tetradecyltrimethylammonium bromide, (C14TMAB)) can change the growth habits of the ZSM‐5 crystals by hindering the regular stacking of zeolite layers from their longer hydrophobic chain. From the XRD pattern of the as‐synthesized samples which were hydrothermally treated for different time, it was found that a lamellar mesostructured intermediate gradually transformed into the sheet‐like ZSM‐5 during hydrothermal process. With a proper amount of cationic surfactant, the thickness of the sheet‐like ZSM‐5 could be controlled to less than 30 nm. Concerning the catalyst application, the toluene disproportionation performance over the sheet‐like ZSM‐5 is 1.5 times higher than that of the commercial ZSM‐5. The higher conversion is ascribed to the faster diffusion amount due to the sheet‐like ZSM‐5.
In this study, one‐pot hydrothermal synthesis of sheet‐like ZSM‐5 as a high‐performance catalyst for toluene disproportionation was carried out using binary surfactants.
Materials
Multiporous carbon (MPC) with a high specific surface area (1121 m2g−1) and mesoporous and microporous structures was prepared by using bamboo biochar (308 m2g−1) as raw material.
Methods
...The preparation involved a CaCO3 activation process, where CaCO3 served as both the template for mesopores and the activating agent for micropores. The template could be easily removed by dilute HCl(aq) solution, making the preparation process simpler and more environmentally friendly compared to using mesoporous SiO2 as a hard template.
Results
The performance of the MPC and biochar as adsorbents for methyl orange (MO) dye was investigated by means of thermal dynamic isotherms and kinetic models tests. The Langmuir isothermal analysis results revealed that the MPC exhibited a significantly higher MO adsorption capacity (344.8 mg g−1) compared to the bamboo biochar (12.4 mg g−1). The adsorption kinetics of the MPC followed a pseudo‐second‐order model.
Conclusion
Overall, the obtained MPC material offers a cost‐effective, environmentally friendly, and efficient solution for removing dyes from aqueous solutions.
Multiporous carbon with a high specific surface area (1121 m2g−1) and mixed mesopore and micropore structure were prepared from bamboo biochar with a specific surface area of 308 m2g−1 via CaCO3 activation.
Materials
In this study, we provided a simple method to extract the silicate species from the waste silica‐containing molding compounds from the semiconducting industry.
Methods
Recycled sodium ...silicate solution was obtained from alkaline extraction of the silica fillers in the waste molding compounds and dried and redissolved in appropriate amount of water.
Results
Porous silica of high surface area (>500 m2g−1) and tunable pore size (1.5–5.0 nm) could be feasibly synthesized by using the recycled sodium silicate as silica source and nature‐friendly homopolymer polyethylene glycol (PEG) as an organic template. The pore size of the PEG‐templating silicas was made tunable by hydrothermal treatment at different pH.
Conclusion
To reduce the emission of CO2 gas from the removal of the PEG template, porous silica with a large surface area has been prepared at a low PEG/sodium silicate weight ratio of 1/20.
This study extracted silicate species from waste silica‐containing molding compounds in the semiconductor industry. Using this recycled sodium silicate as the silica source and eco‐friendly polyethylene glycol (PEG) as an organic template, porous silica with a high surface area (>500 m2g−1) and adjustable pore size (1.5–5.0 nm) can be synthesized.
In recent years, portable electronic devices have flourished, and the safety of lithium batteries has received increasing attention. In this study, nanofibers were prepared by electrospinning using ...different ratios of nylon 66/polyacrylonitrile (PAN), and their properties were studied and compared with commercial PP separators. The experimental results show that the addition of PAN in nylon 66/PAN nanofibrous film used as separator of lithium-ion battery can enhance the porosity up to 85%. There is also no significant shrinkage in the shrinkage test, and the thermal dimensional stability is good. When the Li/LiFePO4 lithium battery is prepared by nylon 66/PAN nanofibrous film used as separator, the capacitor can be maintained at 140 mAhg−1 after 20 cycles at 0.1 C, and the coulombic efficiency is still maintained at 99%, which has excellent electrochemical performance.
A green synthesis method is proposed for the preparation of nitrogen-doped multiporous carbons (denoted as N-MPCs) from water-caltrop shell (WCS) using eggshell waste as both a nitrogen-dopant and an ...activating agent. It is shown that the surface area, porosity, yield and nitrogen content of the as-prepared N-MPCs can be easily controlled by adjusting the activation temperature. Moreover, in oxygen reduction reaction (ORR) tests performed in O
2
-saturated 0.1 M KOH
(aq)
electrolyte containing 1.0 M methanol, the N-MPC catalysts show a high ORR stability and good resistance to methanol corrosion. In addition, as a cathode material in Al-air battery tests, the N-MPCs achieve a power density of 16 mW g
−1
in a saturated NaCl
(aq)
electrolyte. Overall, the results show that the N-MPCs have a promising potential as a green and sustainable material for ORR catalysis applications.
A green synthetic method is proposed for the preparation of nitrogen-doped multiporous carbons (denoted as N-MPCs) from water-caltrop-shell (WCS) biochar by using eggshell waste as both a nitrogen-dopant and an activating agent.
A novel method has been developed to debundle carbon nanotubes (CNTs) and load Pt nanoparticles on them without damaging their graphene structures. In this article, the aniline acts as a very ...efficient dispersing agent to debundle CNTs from 200 to 50 nm at a very low concentration of 0.5% in an IPA/water solution. The aniline-stabilized CNTs have a larger pore volume and larger amount of mesopores than pristine CNTs, and the debundling of CNTs by aniline appears to be a physical rather than a chemical process. Meanwhile, under the presence of aniline, the Pt nanoparticles are anchored on CNTs with a uniform dispersion and small particle size distribution (1.9 ± 0.4, 2.1 ± 0.3, and 2.4 ± 0.4 nm for 14.9%, 29.1%, and 49.0% Pt/CNT, respectively). It is clear that aniline functions as a dispersant and a stabilizer in this paper. These nanocomposites are applied as electrocatalysts for the cathode of a direct methanol fuel cell. The electrochemical active surface areas of Pt/CNT catalysts are higher than that of E-TEK. Compared to the E-TEK cathode catalyst, the mass activity of Pt in 14.9% Pt/CNT is 45.9 W g−1 Pt, which is about 50% higher than that of E-TEK (31.4 W g−1 Pt). The result indicates that aniline is an efficient dispersant and stabilizer for the preparation of Pt nanoparticles deposited on CNTs. Additionally, the whole process, which could be easily scaled up for industrial production, is simple, efficient, and inexpensive.
A uniform dispersion of TiO
2
/SiO
2
hollow nanosphere of 290 nm with a high surface area of more than 100 m
2
g
− 1
is prepared using polystyrene spheres as templates after calcination at 600 °C. ...The TiO
2
/SiO
2
hollow nanospheres are characterized by scanning electron microscopy, transmission electron microscopy, dynamic light scattering, nitrogen adsorption-desorption isotherms, and X-ray diffraction. The TiO
2
/SiO
2
hollow nanospheres are shown to be highly effective in selectively enriching phosphopeptides, resulting in a significant reduction of non-phosphorylated species and an enhanced presence of modified peptides. The favorable results obtained in the present study for the enrichment of phosphoprotein β-casein pave the way toward a similar treatment of other types of biomolecules.
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