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61.
The present article reports on the application of modified multiwalled carbon nanotubes (MMWCNTs) as a new, easily prepared and stable solid sorbent for the preconcentration of trace rhodium ion in aqueous solution. Rhodium ions were complexed with 1-(2-pyridylazo)-2-naphthol (PAN) in the pH range of 3.2-4.7 and then the formed Rh-PAN complex was adsorbed on the oxidized MWCNTs. The adsorbed complex was eluted from MWCNTs sorbent with 5.0 mL of N,N-dimethylformamide (DMF). The rhodium in eluted solution was determined by flame atomic absorption spectrometry (FAAS). Linear range for the determination of rhodium was maintained between 0.16 ng mL−1 and 25.0 μg mL−1 in initial solution. Relative standard deviation for the 10 replicated determination of 4.0 μg mL−1 of rhodium was ±0.97%. Detection limit was 0.010 ng mL−1 in initial solution (3Sbl, n = 10) and preconcentration factor was 120. Sensitivity for 1% absorbance of rhodium (III) was 0.112 μg mL−1. The sorption capacity of oxidized MWCNTs for Rh (III) was 6.6 mg g−1. The effects of the experimental parameters, including the sample pH, flow rates of sample and eluent solution, eluent type, breakthrough volume and interference ions were studied for the preconcentration of Rh3+. The proposed method was successfully applied to the extraction and determination of rhodium in different samples. 相似文献
62.
Moslem Afzali Tayebeh Shamspur Ali Mostafavi 《International journal of environmental analytical chemistry》2019,99(4):328-342
In the present work, a simple procedure is presented for the extraction and determination of pre-concentrated trace amounts of palladium ions through solid phase extraction (SPE) and flame atomic absorption spectrophotometry. This process was performed using Nylon-66/5-(4-dimethylaminobenzylidene) rhodanine composite nanofibres. These nanofibres were produced under optimised conditions via two-axial electrospinning technique and characterised by scanning electron microscopy and Fourier-transform infrared spectroscopy. The effect of experimental parameters including solution pH, the type and volume of eluent and contact time was investigated in extraction and desorption process. Under the optimised conditions, good linearity in the range of 0.07–8 μg L?1 and low detection limit of 0.015 μg L?1 were obtained. High enrichment factor of 187.5 and good relative standard deviation of ±2.2% at 5 μg L?1 of palladium had been achieved. The sorbent capacity for palladium adsorption was obtained 27 mg palladium per gram of nanofibres. So, the SPE was successfully applied to pre-concentrate and determine Pd(II) ions with flame atomic absorption spectrophotometer in real samples. 相似文献
63.
Hannon JB Afzali A Klinke Ch Avouris P 《Langmuir : the ACS journal of surfaces and colloids》2005,21(19):8569-8571
We describe a method to selectively position carbon nanotubes on Al2O3 and HfO2 surfaces. The method exploits the selective binding of alkylphosphonic acids to oxide surfaces with large isoelectric points (i.e. basic rather than acidic surfaces). We have patterned oxide surfaces with acids using both microcontact printing and conventional lithography. With proper choice of the functional end group (e.g., -CH3 or -NH2), nanotube adhesion to the surface can be either prevented or enhanced. 相似文献
64.
High-performance,solution-processed organic thin film transistors from a novel pentacene precursor 总被引:3,自引:0,他引:3
Afzali A Dimitrakopoulos CD Breen TL 《Journal of the American Chemical Society》2002,124(30):8812-8813
The Lewis acid-catalyzed Diels-Alder reaction of the organic semiconductor pentacene with N-sulfinylacetamide yields a soluble adduct. Spin-coated thin films of this adduct undergo solid-phase conversion to form thin films of pentacene at moderate temperatures. Organic thin film transistors fabricated by spin-coating this adduct, followed by thermal conversion to pentacene, exhibit the highest mobility reported to date for a solution-processed organic semiconductor. 相似文献
65.
In this study, tantalum(V) metal organic framework (Ta-MOF) nanostructure was incorporated within polyvinyl alcohol (PVA) nanofibers to prepare an electrospun porous composite as a novel CH4 adsorbent. The crystallinity, thermodynamic behavior, and textural properties of the products were investigated using instrumental analyses techniques. The results confirmed that the developed PVA/Ta-MOF electrospun nanofibrous composite exhibits higher thermal stability, considerable porosity, and larger surface area compared to the parent Ta-MOF. A 2k factorial design was used for systematic study of the adsorption process. The results of response surface methodology (RSM) optimization indicated that the highest methane adsorption can be achieved at 24.40 °C and 3.70 bar in 23.60 min. These nano pore sorbents showed a significant potential for CH4 adsorption due to the presence of Ta-MOF at the surface of nanofibrous composite compared to many other conventional sorbents that have been already used. This study introduces a novel biocompatible/biodegradable nanofibrous composite material with high methane adsorption performance and potentials for other applications. 相似文献
66.
67.
Niloufar Afzali Shahram Tangestaninejad Majid Moghadam Valiollah Mirkhani Adam Mechler Iraj Mohammadpoor‐Baltork Reihaneh Kardanpour Farnaz Zadehahmadi 《应用有机金属化学》2018,32(1)
A heterogeneous catalyst was synthesized by immobilizing Mo(CO)3 in a UiO‐66 metal–organic framework. The benzene ring of the organic linker in UiO‐66 was modified via liquid‐phase deposition of molybdenum hexacarbonyl, Mo(CO)6, as starting precursor to form the (arene)Mo(CO)3 species inside the framework. The structure of this catalyst was characterized using X‐ray diffraction, and chemical integrity was confirmed using Fourier transform infrared and diffuse reflectance UV–visible spectroscopic methods. The metal content was analysed with inductively coupled plasma. Field emission scanning electron microscopy was used to measure particle size and N2 adsorption measurements to characterize the specific surface area. This catalytic system was efficiently applied for epoxidation of alkenes and oxidation of sulfides. The Mo‐containing metal–organic framework was reused several times without any appreciable loss of its efficiency. 相似文献
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69.
Sayed Z. Mohammadi Mohammad A. Karimi Daryoush Afzali Fatemeh Mansouri 《Central European Journal of Chemistry》2010,8(6):1273-1280
Two series of activated carbon have been prepared by chemical activation of Amygdalus Scoparia shell with phosphoric acid or zinc chloride for the removal of Pb(II) ions from aqueous solutions. Several methods were employed
to characterize the active carbon produced. The surface area was calculated using the standard Brunauer-Emmet-Teller method.
The microstructures of the resultant activated carbon were observed by scanning electron microscopy. The chemical composition
of the surface resultant activated carbon was determined by Fourier transform infrared spectroscopy. In the batch tests, the
effect of pH, initial concentration, and contact time on the adsorption were studied. The data were fitted with Langmuir and
Freundlich equations to describe the equilibrium isotherms. The maximum adsorption capacity of Pb(II) on the resultant activated
carbon was 36.63 mg g−1 with H3PO4 and 28.74 mg g−1 with ZnCl2. To regenerate the spent adsorbents, desorption experiments were performed using 0.25 mol L−1 HCl. Here we propose that the activated carbon produced from Amygdalus Scoparia shell is an alternative low-cost adsorbent for Pb(II) adsorption. 相似文献
70.
Ziba Khodaee Asieh Yahyazadeh Nosrat O. Mahmoodi 《Journal of heterocyclic chemistry》2013,50(2):288-292
The synthesis and structural elucidation of some novel 5,5′‐disubstituted spiro and nonspiro‐bis‐hydantoins are reported. The Bucherer Burge's method has been modified for the preparation of some 5,5′‐substituted bis(imidazolidine‐2,4‐dione) derivatives starting with diketones ( 1–5 ) and dialdehydes ( 6 , 7 ). In some cases, diastereoisomeric mixtures of compounds were obtained. The resulting bis‐hydantoins ( 8–11 , 13 , 14 ) have not to our knowledge been previously reported in the literature. 相似文献