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141.
Synthesis and characterization of the new styrene microspheres with pendant methylenethiol groups are presented. At the first stage, the polymeric matrices were obtained by the suspension–emulsion polymerization of monomers: styrene (St) with 2,3‐(2‐hydroxy‐3‐methacryloyloxypropoxy)naphthalene (NAF.DM) or (bis[4(2‐hydroxy‐3‐methacryloyloxypropoxy)phenyl]sulfide (BES.DM) or divinylbenzene (DVB). At the second stage, the modification of the sythesized matrices was performed as follows: the matrices were reacted with paraformaldehyde in the presence of hydrochloric acid forming chloromethyl derivatives. Next, by reaction with thiourea, a thiouronium salt was obtained, and then the hydrolysis with NaOH solution and acidification with HCl were carried out. Finally, microspheres with –CH2SH groups on their surface were obtained. The –SH group content (elemental analysis), thermal properties (thermogravimetric analysis), Fourier transform infrared as well as the swelling characteristics of the functional microspheres were examined. The surface texture was also visualized by the atomic force microscopy (AFM) method. The obtained polymers were screened towards sorption of Cu(II) ions. It was found that a better correlation between the experimental Cu(II) uptake and the theoretical curves predicted by the Langmuir or Freundlich models is obtained in the case of the DVB–St–SH polymer. In the case of the BES.DM–St–SH and 2,3‐NAF–St–SH ones, the Freundlich model corresponded quite well to the experimental data. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
142.
A mathematical model is constructed and solved that could describe the dynamic behavior of the adsorption of a solute of interest in single and stratified columns packed with partially fractal porous adsorbent particles. The results show that a stratified column bed whose length is the same as that of a single column bed, provides larger breakthrough times and a higher dynamic utilization of the adsorptive capacity of the particles than those obtained from the single column bed, and the superior performance of the stratified bed becomes especially more important when the superficial velocity of the flowing fluid stream in the column is increased to accommodate increases in the system throughput. This occurs because the stratified column bed provides larger average external and intraparticle mass transfer and adsorption rates per unit length of packed column. It is also shown that increases in the total number of recursions of the fractal and the ratio of the radii between larger and smaller microspheres that make up the partially fractal particles, increase the intraparticle mass transfer and adsorption rates and lead to larger breakthrough times and dynamic utilization of the adsorptive capacity of the particles. The results of this work indicate that highly efficient adsorption separations could be realized through the use of a stratified column comprised from a practically reasonable number of sections packed with partially fractal porous adsorbent particles having reasonably large (i) total number of recursions of the fractal and (ii) ratio of the radii between larger and smaller microspheres from which the partially fractal particles are made from. It is important to mention here that the physical concepts and modeling approaches presented in this work could be, after a few modifications of the model, applied in studying the dynamic behavior of chemical catalysis and biocatalysis in reactor beds packed with partially fractal porous catalyst particles. 相似文献
143.
The phase behavior of the systems water/sucrose laurate/ethoxylated mono‐di‐glyceride/oil was investigated as function of temperature and the weight ratio of EMDG in the mixed surfactants. The oils were R (+)‐limonene, isopropylmyristate, and caprylic‐capric triglyceride. This study demonstrates that the phase inversion temperature (PIT) decreases and the efficiency of the mixed surfactants (γ¯) increase as the weight ratio of the EMDG in the mixed surfactants increases. R (+)‐limonene gave lower phase inversion temperatures and higher efficiencies compared to isopropylmyristate, and caprylic‐capric triglyceride. The solubilization capacity of the system water/sucrose laurate/oil increased upon the addition of ethoxylated mono‐di‐ glyceride which stabilize the surfactant layer and increase the interfacial area. 相似文献
144.
145.
Characterization and kinetic performance of 2.1 × 100 mm production columns packed with new 1.6 μm superficially porous particles 下载免费PDF全文
Fabrice Gritti Stephen Shiner Jacob N. Fairchild Georges Guiochon 《Journal of separation science》2014,37(23):3418-3425
The overall kinetic performance of three production columns (2.1 mm × 100 mm format) packed with 1.6 μm superficially porous CORTECS‐C18+ particles was assessed on a low‐dispersive I‐class ACQUITY instrument. The values of their minimum intrinsic reduced plate heights (hmin = 1.42, 1.57, and 1.75) were measured at room temperature (295 K) for a small molecule (naphthalene) with an acetonitrile/water eluent mixture (75:25, v/v). These narrow‐bore columns provide an average intrinsic efficiency of 395 000 plates per meter. The gradient separation of 14 small molecules shows that these columns have a peak capacity about 25% larger than similar ones packed with fully porous BEH‐C18 particles (1.7 μm) or shorter (50 mm) columns packed with smaller core–shell particles (1.3 μm) operated under very high pressure (>1000 bar) for steep gradient elution (analysis time 80 s). In contrast, because their permeabilities are lower than those of columns packed with larger core–shell particles, their peak capacities are 25% smaller than those of narrow‐bore columns packed with standard 2.7 μm core–shell particles. 相似文献
146.
锂离子电池的有机正极材料由于具有比容量高、环境友好和廉价等优点,近年来成为研究的热点.但是,有机电极材料在液态电解液中的溶解流失易导致其容量迅速衰减,严重限制了它们的实际应用.本工作基于聚(甲基丙烯酸酯)/聚乙二醇的准固态电解质,考察了以柱[5]醌为正极的准固态锂二次电池的电化学性能.结果显示,柱[5]醌正极不仅保持了高容量的特性(首次放电容量410 mA h/g),并且循环寿命得到了有效提高.0.2 C下循环100周后,电极的容量保持率为88.5%,显示了柱[5]醌在高比能量准固态锂离子电池中的应用潜力. 相似文献
147.
以三聚氰胺为氮源,商用活性炭为研究对象,通过“浸渍吸附+高温热处理”的方式制得系列氮掺杂活性炭,并用于催化氧化合成氮甲基氧化吗啉(NMMO)。采用N2吸附/脱附、Raman、XPS等对氮掺杂活性炭的孔结构和表面性质进行了表征。结果表明:随着三聚氰胺负载量的增大,氮掺杂活性炭的表面碱性含氮官能团含量增大,进而体现出更好的催化氧化合成NMMO活性。最佳催化剂(ACO850-20N)在催化剂加量为0.02 wt%,反应温度70 ℃和反应时间4 h的工艺条件下,氮甲基吗啉的转化率和NMMO收率可达99.76%和94.31%。
相似文献
148.
《Arabian Journal of Chemistry》2022,15(10):104136
Facile synthesis of two 2-anthracene ammonium-based magnetic ionic liquids (MILs), 2-anthracene ammonium tetrachloroferrate (III) ([2A-A]FeCl4) and 2-anthracene ammonium trichlorocobaltate (II) ([2A-A]CoCl3) was performed by protonation of 2-aminoanthracene, followed complexation with FeCl3/CoCl2. The MILs were tested in the adsorptive removal of Cd2+, As3+, Pb2+ and Cr3+ from water sources. Upon treatment with 10 mg dosage of MILs in 10 mL aqueous solution of 50 ppm each of Cd2+, As3+, Pb2+ and Cr3+, adsorption capacity (mg/g) in the range of 5.73–55.5 and 23.6–56.8 for [2A-A]FeCl4 and [2A-A]CoCl3 respectively were recorded. Thus, the optimization, kinetic and isotherms studies were conducted using the [2A-A]CoCl3 adsorbent. The [2A-A]CoCl3 was more effective in pH 7–9, and equilibrium adsorption was achieved after 60 min contact time. The adsorption process proceeded via the Pseudo-second order pathway and the Langmuir isotherm model is the best fit for the adsorption process (with qmax = 227 – 357 mg/g) of all the targeted metal ions. The [2A-A]CoCl3 adsorbent demonstrated practicality with large distribution and selectivity coefficients of the targeted ions, and up to six times regeneration. 相似文献
149.
K-ion batteries (KIBs) attract considerable attention due to the abundance of K, high-working voltages, and chemical similarity with Li, enabling the utilization of mature Li-ion technology. However, shortage of high-performance anode materials is a critical obstacle for the development of KIBs. Through first-principles swarm-intelligence structural search, we identify a potential anode material, the C6S monolayer, which provides not only a remarkably high specific capacity of 1546 mAh/g but also a low diffusion barrier of 0.11 eV and a low open-circuit voltage of 0.21 V. Inherent metallicity originates from delocalized π electrons. 相似文献
150.
Ricardo Aguilar-Villalva Gustavo A. Molina Beatriz Liliana España-Sánchez Luis Fernando Díaz-Peña Alberto Elizalde-Mata Edgar Valerio Cristy Azanza-Ricardo Miriam Estevez 《Arabian Journal of Chemistry》2021,14(7):103239
In recent years, the food, pharmacy, and cosmetic industries have focused on the search of natural compounds with antimicrobial and antioxidant properties; commonly, these compounds are obtained from Kingdom plantae. The aim of the present work is comparing antibacterial and antioxidant capacity of Annona cherimola Mill leaves, using different extraction methods. The ultrasound assisted extraction technique (UAE) was compared with conventional techniques: Soxhlet and maceration. Water and ethanol were used as solvents for leaves extractions performed with these three methods. The main acetogenins reported in Annona cherimola Mill and Annona muricata L. species were simulated using the functional hybrid B3LYP and to confirm its presence, analysis of the compound composition was performed using FT-IR, UV–Vis and HPLC. Total phenolics (TP) and flavonoids (TF) were determined by spectroscopy techniques and novel Differential Pulse Voltammetry (DPV) electrochemical technique. Total Antioxidant Capacity (TAC) of the extracts was measured, using the DPPH, FRAP and CUPRAC techniques. The highest antioxidant content was found in the Soxhlet water extracts; even so, the UAE technique presented an attractive alternative due to considerable reduction in extraction time, which was greater than 99%, and possible selectivity in compounds extraction. Finally, antibacterial activity of the extracts was evaluated, obtaining the best results against gram-positive bacteria using UAE water extract. In this way, the UAE technique presents an excellent extraction option due to the considerable reduction in time and energy, as well as the increase in antibacterial activity. 相似文献