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排序方式: 共有235条查询结果,搜索用时 15 毫秒
231.
Yaser Nabavi Larimi Mohammad Hassan Mallah Mohammad Ali Moosavian Jaber Safdari 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(3):1511-1518
The purpose of present study is to fabrication of a magmolecule (amino-functionalized magnetite nanoparticles) and evaluation of its adsorption capacity for selenite (SeO3 2?) ions from nuclear wastewater. To accomplish this, synthesized magnetite nanoparticles is coated with a layer of SiO2 in order to be chemically stable and then functionalized with 3-aminopropyl triethoxysilane (APTES) to be more effective. Adsorption of SeO3 2? ions was investigated in batch technique. The effect of parameters such as solution pH, presence of competing anions using sulfuric acid and nitric acid (NO3 ?, HSO4 ? and SO4 2?) and temperature were studied. Maximum adsorption occurred at pH 2.4 for magnetite (naked nanoparticle) and 1.7 for functionalized nanoparticles, while the dose of adsorbent was 1 g/L and selenite ion concentration was 50 mg/L. sulfuric acid was selected as the better acidic agent for controlling pH of solution. Thermodynamic parameters were also calculated and it has been found that the adsorption was endothermic. The obtained result showed that the naked particles had more adsorption capacity but it has been suggested usage of functionalized particles in the magmolecule process duo to stability and reusable capability. 相似文献
232.
Malek Taher Maghsoodlou Nourollah Hazeri Sayyed Mostafa Habibi Khorasani Hadi Mahmoudi Moghaddam Mahmoud Nassiri Jaber Salehzadeh 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1713-1721
Stable crystalline phosphorus ylides containing chlorine and sulfur were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylene-dicarboxylates in the presence of 6-chloro-2-benzoxazolethiol and 2-chloro-phenothiazine. These stable ylides exist in solution as a mixture of two geometrical isomers. This is caused by the conjugation of the ylide moiety with the adjacent carbonyl group, which results in a restricted rotation around the respective carbon-carbon bond. 相似文献
233.
Saeed Nojavan Zeinab Tahmasebi Tina Bidarmanesh Hamideh Behdad Mahnaz Nasiri‐Aghdam Sozan Mansori Ahmad Pourahadi 《Journal of separation science》2013,36(19):3256-3263
An electromembrane extraction procedure coupled with HPLC and visible detection was applied for the extraction of three textile azo dyes as organic salts. The extraction parameters such as extraction time, applied voltage, pH range, and concentration of salt added were optimized. A driving force of 60 V was applied to extract the analytes through 2‐nitrophenyl octyl ether, used as the supported liquid membrane, into a neutral aqueous solution. This method required 20 min extraction time from a neutral sample solution. The proposed microextraction technique provided good linearity with correlation coefficients from 0.996 to 0.998 over a concentration range of 1.0–1000.0 ng/mL. The LODs of dyes were 0.30–0.75 ng/mL, while the reproducibility ranged from 6.7 to 12.9% (n = 6). Also, enrichment factors of 96–162 that corresponded to the recoveries ranging from 48 to 81% were achieved. Finally, the application of this new method was demonstrated on wastewater samples and some plants grown in contaminated environments. Excellent selectivity was obtained as no interfering peaks were detected. 相似文献
234.
Habibi-Khorassani SM Ebrahimi A Maghsoodlou MT Same-Salari S Nasiri S Ghasempour H 《Magnetic resonance in chemistry : MRC》2011,49(5):213-220
Herein, a series of separate dynamic (1)H NMR effects are reported at different temperatures within a particular enaminoester involving a phenanthridine. These effects are attributed to restricted rotation around the two single bonds such as carbon-carbon (H(a)-C-C-H(b)) and nitrogen-carbon (NCCOOCH(3)). Activation energies (E(a)) for these interconversion processes in their rotational isomers are equal to 20 and 20 ± 1 kJ mol(-1), respectively. In addition, three dynamic (1)H NMR effects are investigated at different temperatures for a particular phosphorus ylide involving a 2-indolinone around the carbon-carbon single bond (H-C-C-PPh(3)) within the two Z- and E-rotational isomers and partial carbon-carbon double bond (OCH(3)-C=C-PPh(3)). Activation energies (E(a)) for these interconversion processes in rotational isomers are equal to 53, 63 and 73 ± 1 kJ mol(-1) , respectively. This behavior was also observed for other phosphorus ylide containing 2-mercaptobenzoxazole around the carbon-carbon single bond and partial carbon-carbon double bond with their relevant activation energies containing 13, 10 and 75 ± 1 kJ mol(-1), respectively. 相似文献
235.
Hamid Entezar Mehdi Parisa Esmaili Mehdi Nasiri Sarvi Somayeh Asgary 《Optical and Quantum Electronics》2018,50(9):344
Silver oxide nano layers were prepared by RF magnetron sputtering on amorphous SiO2 substrates. O2 pressure in chamber was varied from 1 to 4 and 7 mTorr during growth process. The effects of different O2 pressure on structural, morphological and optical properties of the films were investigated by means of X-ray diffraction, scanning electron microscopy, atomic force microscopy and UV–Vis spectroscopy analyses. Optical reflectance measured in the wavelength of 350–950 nm by spectroscopy. Other optical properties and optical band gaps were calculated using Kramers–Kronig relations. The X-ray diffraction measurements showed change in crystalline structure with increasing O2 pressure. Preferred orientation has been changed to another growth orientation at 4 mTorr O2 pressure. The Atomic force microscope images showed increasing in roughness consistently by increasing oxygen pressure. The thickness of the thin films decreases (from 217 to 180 nm) with increasing O2 pressure. Optical results revealed that the highest optical band gap of 3.1 eV and the highest transmittance of?~?80% were achieved at lower O2 pressure (1 mTorr). 相似文献