The mesoporous silicas (MCM-41 and MCM-48) are synthesized by hydrothermal method, which are characterized by XRD and BET techniques. The application of mesoporous silicas for the sorption of U(VI) from aqueous solution are studied by using batch technique under ambient condition. The effects of contact time, solid-to-liquid ratio (m/V), solution pH, ionic strength and temperature are determined, and the results indicate that the sorption of U(VI) to MCM-41 or MCM-48 are strongly dependent on pH values but independent of ionic strength. Compared with Langmuir model, the sorption isotherms can be simulated by Freundlich model well according to the high relative coefficients. The parameters for Langmuir and Freundlich sorption isotherms are calculated from the temperature at 298, 318 and 338 K, respectively, and the results suggest that the sorption of U(VI) on MCM-41 or MCM-48 is a spontaneous and exothermic process. In contrast to its sorption capacity for U(VI), MCM-48 is a suitable material for the preconcentration of U(VI) from large volumes of aqueous solutions. 相似文献
In this research TiO2 sample was synthesized by a simple sol–gel method and was characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) techniques. The XRD result indicated that the obtained product was anatase titanium dioxide with high purity, the TEM image clearly showed that the particle sizes of TiO2 nanoparticles were in the range of 30–70 nm, and the measured BET surface area of the heated TiO2 nanoparticles was 147.14 m2/g. In this work, the prepared TiO2 sample was used as a new adsorbent for the adsorption of radionuclide Co(II) ions from aqueous solutions, and the influence of pH, contact time, ionic strength and temperature in the presence or absence of humic acid/fulvic acid (HA/FA) were also investigated. The experimental results indicated that the adsorption of Co(II) ions onto TiO2 was strongly pH-dependent. Based on the surface complexation, the presence of HSs enhanced the adsorption of Co(II) ions and the influence of Co(II) adsorption onto FA–TiO2 hybrids was much stronger than that of HA–TiO2 at pH values of 2.0–9.0. Adsorption of Co(II) ions onto TiO2 powder was strongly dependent on ionic strength. The adsorption process mainly occured in the first contact time of 2 h and could be fitted by a pseudo-second-order rate model. The calculated thermodynamic data indicated that the adsorption of Co(II) ions onto TiO2 was a spontaneous process and favorable at high temperatures. 相似文献
A sensor based on gold nanoparticle on the surface of L-cysteine modified gold electrode is prepared. Electrochemical behavior of dopamine hydrochloride is investigated. The linear relation between peak current of dopamine hydrochloride and scan speed in the range of 10 to 1000 mV s?1 indicates that a diffusion-adsorption controls the process. The linearity range is 1.05 × 10?5–7.38 × 10?4 M with detection limit of 1.05 × 10?6 M. The recoveries were in the range from 99.8 to 101.5% with relative standard deviations of 1.3 ~ 2.3% (n = 6). The modified electrode under ambient conditions over a period of 2 weeks has an excellent repeatability and reproducibility. 相似文献
Electrochemical synthesis of gold nanoparticles on the surface of pyrolytic graphite using penicillin as a stabilizing reagent was proposed. The gold nanoparticles were characterized by scanning electron microscopy, cyclic voltammetry, IR spectra, UV spectra, and powder X-ray diffraction spectra. The electro-chemical catalysis of penicillin for α-naphthylamine was demonstrated. 相似文献
Gastrin releasing peptide receptors (GRPRs) are one of the most interesting targets over expressed in various tumors. Due to the superior potential of the GRPR antagonist analogs, they have been studied in the tumor radio imaging and therapy field. However, typical antagonists suffered the shortcomings of no internalization and poor binding affinity which hampered their applications in radiotherapy. Therefore, we attempted to introduce Oligoarginines (cell penetrating peptides) to RM26, aiming to increase the binding affinity or even trigger the internalization of the peptides on cells. The results showed Arg6 as the most potent CPP, significantly enhanced the binding avidity of RM26 to the GRPR.
Electrocatalytic water splitting into H2 and O2 is a key technology for carbon‐neutral energy. Here, we report a modular materials design leading to noble metal‐free composite electrocatalysts, which combine high electrical conductivity, high OER and HER reactivity and high durability. The scalable bottom‐up fabrication allows the stable deposition of mixed metal oxide nanostructures with different functionalities on copper foam electrodes. The composite catalyst shows sustained OER and HER activity in 0.1 m aqueous KOH over prolonged periods (t>10 h) at low overpotentials (OER: ≈300 mV; HER: ≈100 mV) and high faradaic efficiencies (OER: ≈100 %, HER: ≈98 %). The new synthetic concept will enable the development of multifunctional, mixed metal oxide composites as high‐performance electrocatalysts for challenging energy conversion and storage reactions. 相似文献
Two catechin epimers and their non‐covalent complexes with γ‐cyclodextrin were studied by using ion mobility coupled with mass spectrometry (IM‐MS). Rapid separation of complexes was achieved with the peak‐to‐peak resolution reaching 0.86 after optimization of IM condition. Collision cross section (CCS) was measured to explore the structural difference of complexes. A gap of 11.75 Å2 between two complexes was found. Molecular modeling and theoretical CCS calculation were adopted to explain the measurement results. Two binding ways of both complexes were found and the calculated CCS corresponds accurately to the measured CCS. Quantification of catechins in mixtures was performed and the relative error was less than 15%, indicating the effectiveness of quantification by IM‐MS. 相似文献
A highly selective and efficient LC–MS/MS method was developed to determine the plasma concentration of magnolol, hesperidin, neohesperidin and geniposide following oral administration of Zhi‐Zi‐Hou‐Po decoction in normal and depressed rats. Plasma samples were pretreated by protein precipitation with methanol. Chromatographic separation was performed on an XTerra® MS C18 column using a gradient elution with a mobile phase composed of acetonitrile–0.1% aqueous formic acid. The proposed method was validated to be specific, accurate and precise for the analytes determination in plasma samples. The calibration curves displayed good linearity over definite concentration ranges for the analytes. The intra‐ and inter‐day precision of the proposed method at three different levels were all within <11.13% and the relative errors ranged from ?8.46 to 8.93%. The recovery of the four compounds ranged from 82.72 to 89.08% and no apparent matrix effect was observed during sample analysis. After full validation, the established method was successfully applied for comparing the pharmacokinetics of four components between normal and depressed rats. The results showed that the AUC and Cmax of four analytes in depressed rats were significantly different from those in normal rats and might provide helpful information to guide the clinical use of Zhi‐Zi‐Hou‐Po to treat depression. 相似文献