In this study, pillared layered clays were prepared by modifying Vietnamese bentonite with polymeric Al and Fe. The obtained materials were characteristic of X-ray diffraction analysis, thermal analysis, and nitrogen adsorption/desorption isotherms. The results indicated that hydroxy-aluminum ([Al13O4(OH)24(H2O)12]7+) and poly-hydroxyl-Fe or polyoxo-Fe cations were intercalated into layers of clay, resulting in an increase of d001 values and of the specific surface areas compared with those of initial bentonite. Modified bentonites were employed to adsorb As(V) from aqueous solution. The adsorption of As(V) was strongly dependent on solution pH, and the maximum adsorption of modified bentonites was obtained in the pH 3.0 for Fe-bentonite and the pH 4.0 for Al-bentonite. The equilibrium adsorption study showed that the data were well fit by the Langmuir isotherm model. The maximum monolayer adsorption capacity of As(V) at 30°C derived from the Langmuir equation was 35.71 mg/g for Al-bentonite and 18.98 mg/g for Fe-bentonite. Adsorption kinetics, thermodynamics, and reusability of modified bentonites have been addressed.
Zeolite imidazole framework-8 (ZIF-8) was prepared by the hydrothermal process. e obtained ZIF-8 was a characteristic of X-ray-diffraction (XRD), transmission electron microscope (TEM), thermal gravity-differential thermal analysis (TG-DTA), and dynamic light scattering (DLS). e obtained ZIF-8 possessed large specific area and was highly dispersed. Its morphology consisted of nanospherical particles with 30-50 nm in diameter. Chemical stability of ZIF-8 in different conditions was studied.e ZIF-8 was used as an electrode modifier for the determination of trace levels of lead. e parameters including solvents and solution pH were investigated. e repeatability, reproducibility, accuracy, linear range, limit of detection, and limit of quantitation were also addressed. e results showed that ZIF-8 is a potential electrode modifier for differential pulse anodic stripping method to determine Pb(II) in aqueous solution.
In this paper, ZIF-11 material was synthesized from benzimidazole and different zinc salt sources at room temperature. The obtained samples were characterized using XRD, SEM, FTIR and TGA measurements. The results showed that the synthesized materials had nano-size, and uniformity with the sharp dodecahedrons structure of ZIF-11. Zinc sources had an influence on the size and nature of the ZIF-11 crystal. The average crystalline size of the nanoparticles calculated by Scherrer equation were 85.5 nm for sample of zinc nitrate, 91.9 nm for sample of zinc chloride and 111.5 nm for sample of zinc acetate. The obtained samples had high thermal stability ( 460 °C). The adsorption capacity of the synthesized materials for iodine from aqueous solution was very high (236 mg/g).
Felodipine is a calcium channel blocker used for hypertensive and unstable angina treatments. The sustained release formulations of felodipine have advantages of achieving good therapeutic effects, increasing the bioavailability, decreasing dosing times per day and reducing side effects.The aim of our study was to study the formulation screening, then use an experiment design for formulating a hydrophilic matrix sustained release tablet of felodipine. Methods: The optimization process had the influences of the chosen excipients (including HPMC E4M, HPMC E15LV) on the drug release. Three dependent variables were percentages of released felodipine at the sampling times 2h, 6h, 10h (Y2, Y6, Y10, respectively). Results: The release profile from the optimized formula almost met the predicted release profile and was similar to reference tablets. The kinetics of drug release the optimized tablets and reference tablets were also followed the Korsmeyer – Peppas model.Conclusion: The optimized formula was obtained, and the in vitro release profile was similar to the predicted profile and reference tablets.
In this paper, ZIF-11 materials were synthesized from benzimidazole (BIm) and zinc acetate in different solvent systems at room temperature. The obtained samples were characterized using XRD, SEM, FTIR and TGA measurements and tested for toluene and iodine adsorption ability. The results show that the synthesized materials had nano-size, and uniformity with the sharp rhombic dodecahedrons structure of ZIF-11. The studied solvent systems almost did not affect the crystal size of the materials, but had an small influence on their thermal stability and the toluene adsorption ability. The samples synthesized in methanol-toluene and ethanol-toluene solvent systems had higher thermal stability than those synthesized in ethanol-xylene and ethanol-benzene solvent systems. The obtained materials had high adsorption ability for toluene. Adsorption capacity reached 303.5 mg/g, 306.1 mg/g, 295.6 mg/g and 279.7 mg/g for the materials synthesized in methanol-toluene, ethanol-toluene, ethanol-xylene and ethanol-benzene solvent systems, respectively. The samples also had high adsorption ability for the iodine from aqueous solution and the studied solvent systems almost did not affect iodine adsorption ability of the materials.
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