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11.
The sorption behaviour of 2.5 × 10−5 M solution of Cd(II) on polyurethane foam (PUF) from iodide medium have been investigated. The conditions were optimized from aqueous solutions of different pH (1-10) and of acids of varied concentration (0.01-1.0 M). The maximum concentration of KI was found to be 0.24 M and equilibration time was established to be 20 min. The data successfully followed the Freundlich and Dubinin-Radushkevich (D-R) isotherms at low metal ion concentration while Langmuir isotherm followed at higher metal ion concentration. The Freundlich parameter 1/n = 0.66 ± 0.02 have been evaluated whereas D-R isotherm yields the sorption free energy E = 10.5 ± 0.1 kJ mol−1 indicating ion exchange type chemisorption. The monolayer coverage (XL) constant of Langmuir isotherm was found to be 23.7 ± 0.4 mg g−1. The numerical values of thermodynamics parameters enthalpy (ΔH), entropy (ΔS) and Gibbs free energy (ΔG) indicated the endothermic and spontaneous nature of sorption. The Scatchard plot analysis was tested to evaluate the binding sites of the PUF and stability constants of sorption were determined. On the basis of these parameters, the sorption mechanism was discussed. Among the foreign ions tested, Pb(II), Hg(II), cyanide and nitrite should be absent. The clean separation of Cd(II) from Zn(II) ions in the ratio 1:250, respectively, was achieved by column chromatography. 相似文献
12.
We report molecular dynamics (MD) simulations of the solvation dynamics of Coumarin 153 in liquid dimethylsulfoxide using two distinct sets of partial charges for the coumarin probe. The excited state dipole moment of the coumarin and the dynamic Stokes shift in solution depend significantly on the type of charge distributions used. Nevertheless, the overall characteristics of the solvation responses obtained from both sets of charges are very similar and show good agreement with time-dependent Stokes shift experiments. Microscopic details of the solvent reorganization around the probe are discussed in light of the charge transfer upon photoexcitation. 相似文献
13.
M. N. Cheema M. Mufazzal Saeed Akbar Ali Munir Ahmed 《Journal of Radioanalytical and Nuclear Chemistry》1994,178(1):153-163
Extraction of Hg(II), Se(IV), Mn(II) and Co(II) has been carried out with 1-phenyl-3-methyl-4-trifluoroacetyl-2-pyrazolin-5-one (HPMTFP) and triphenylphosphine oxide (TPPO) into chloroform from pH 1–10. Quantitative extraction of Hg(II), Mn(II) and Co(II) at pH 4 with equimolar 0.05M (PMTFP+TPPO) in chloroform was observed. Se(IV) remains unextracted at this pH range. The stoichiometric composition of the extracted complexes M(PMTFP)2·nH2O (M=Mn, Hg), M(PMTFP)2·2TPPO (M=Mn and Co) and Co(PMTFP)2·TPPO·H2O at less than 0.1M TPPO has been established. The formation constantsK
m,0 andK
m,n and stability constants
m,n have been computed. The analytical method developed was applied to the IAEA standard reference material (SRM) potato fluor V-4 for the determination of these elements using NAA technique. 相似文献
14.
Munir M. Ahmad Martin R. Bryce Joan Halfpenny Larry Weiler 《Tetrahedron letters》1984,25(38):4275-4278
Bis(triphenylphosphoranylidene)ammonium iodide (PPN+I?) forms a 2:3 complex with TCNQ [(PPN)2(TCNQ)3(CH3CN)2] that provides an example of a TCNQ complex containing acetonitrile in the crystal lattice; the material is a semi-conductor with trimerised TCNQ stacks. 相似文献
15.
The decomposition of initially hydrated powders of iron(III) sulfate was carried out in air over the temperature range 823–923 K. The decomposition process, which gave Fe2O3 as a solid product, was seen to have zero-order kinetics and an activation energy of 219 kJ·mol–1. The nature of the product and the kinetics of decomposition were the same for samples decomposed in air and in argon. Sulfate samples with additives of FeS and Fe2O3 were also decomposed under similar conditions and the results confirmed the zero-order kinetics (for the case of the Fe2O3 additives) and the lack of effect of FeS on the decomposition of iron(III) sulfate.
This work was supported by a grant from the U.S. Department of Energy, Office of Basic Energy Sciences. The authors gratefully acknowledge this support. 相似文献
Zusammenfassung Anfänglich hydratiertes Eisen(III)-sulfatpulver wurde in Luft im Temperaturbereich 823–923 K zersetzt. Für die Reaktionsordnung des Zersetzungsprozesses, der als Endprodukt festes Fe2O3 lieferte, wurde Null und für die Aktivierungsenergie 219 kJ·mol–1 ermittelt. Die Art des Produktes und der Kinetik der Zersetzung war in Luft und Argon gleich. Unter den gleichen Bedingungen wurden auch Sulfatproben mit Zusätzen von FeS und Fe2O3 zersetzt. Die Ergebnisse bekräftigen sowohl die nullte Reaktionsordnung (im Falle von Fe2O3 Zusätzen) als auch einen fehlenden Einfluß von FeS auf die Zersetzung von Eisen(III)-sulfat.
823–923 . , , , 219 · –1. . FeS Fe2O3 . ( Fe2O3) - .
This work was supported by a grant from the U.S. Department of Energy, Office of Basic Energy Sciences. The authors gratefully acknowledge this support. 相似文献
16.
Shamsa Munir Afzal Shah Abdur Rauf Amin Badshah Hidayat Hussain Zia-ur-Rehman Zahoor Ahmad 《Comptes Rendus Chimie》2013,16(12):1140-1146
The present work reports the redox mechanism of 5-hydroxynaphthalene-1,4-dione (HND), commonly known as juglone, in buffered aqueous media having 50% of ethanol. HND followed different mechanistic routes depending upon the pH of the media and more than one pKa were evaluated from the changes in the slope of the Ep vs. pH plot. The change of pH from acidic to neutral conditions was found to switch the mechanism from CEC to EE mechanism. Pulse techniques were utilized to determine the number of electrons involved in the oxidation and/or the reduction step and to ensure the nature of the redox process. Based upon the obtained results, an electrode reaction mechanism was proposed. Computational studies of HND supported the experimental results. UV-Visible spectroscopy was also employed for the detailed characterization of the compound in a wide range of pH and for the determination of its pKa. 相似文献
17.
Javed Iqbal Banzeer Ahsan Abbasi Tariq Mahmood Safia Hameed Akhtar Munir Sobia Kanwal 《应用有机金属化学》2019,33(8)
In the present report, Nickel oxide nanoparticles (NiONPs) were synthesized using Rhamnus virgata (Roxb.) (Family: Rhamnaceae) as a potential stabilizing, reducing and chelating agent. The formation, morphology, structure and other physicochemical properties of resulting NiONPs were characterized by Ultra violet spectroscopy, X‐ray diffraction (XRD), Fourier Transform Infrared analysis (FTIR), Scanning electron microscopy (SEM), Energy‐dispersive‐spectroscopy (EDS), Transmission electron microscopy (TEM), Raman spectroscopy and dynamic light scattering (DLS). Detailed in vitro biological activities revealed significant therapeutic potential for NiONPs. The antimicrobial efficacy of biogenic NiONPs was demonstrated against five different gram positive and gram negative bacterial strains. Klebsiella pneumoniae and Pseudomonas aeruginosa (MIC: 125 μg/mL) were found to be the least susceptible and Bacillus subtilis (MIC: 31.25 μg/mL) was found to be the most susceptible strain to NiONPs. Biogenic NiONPs were reported to be highly potent against HepG2 cells (IC50: 29.68 μg/ml). Moderate antileishmanial activity against Leishmania tropica (KMH23) promastigotes (IC50: 10.62 μg/ml) and amastigotes (IC50: 27.58 μg/ml) cultures are reported. The cytotoxic activity was studied using brine shrimps and their IC50 value was recorded as 43.73 μg/ml. For toxicological assessment, NiONPs were found compatible towards human RBCs (IC50: > 200 μg/ml) and macrophages (IC50: > 200 μg/ml), deeming particles safe for various applications in nanomedicines. Moderate antioxidant activities: total antioxidant capacity (TAC) (51.43%), 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) activity (70.36%) and total reducing power (TRP) (45%) are reported for NiONPs. In addition, protein kinase and alpha amylase inhibition assays were also performed. Our results concluded that Rhamnus virgata synthesized NiONPs could find important biomedical applications with low cytotoxicity to normal cells. 相似文献
18.
Yu Dong Tariq Mosaval Hazim J. Haroosh Rehan Umer Hitoshi Takagi Kin‐Tak Lau 《Journal of Polymer Science.Polymer Physics》2014,52(9):618-623
This pilot study elaborates the development of novel epoxy/electrospun polylactic acid (PLA) nanofiber composites at the fiber contents of 3, 5, and 10 wt % to evaluate their mechanical and thermal properties using flexural tests and differential scanning calorimetry (DSC). The flexural moduli of composites increase remarkably by 50.8 and 24.0% for 5 and 10 wt % fiber contents, respectively, relative to that of neat epoxy. Furthermore, a similar trend is also shown for corresponding flexural strengths being enhanced by 31.6 and 4.8%. Fractured surface morphology with scanning electron microscopy (SEM) confirms a full permeation of cured epoxy matrix into nanofiber structures and existence of nondestructive fibrous networks inside large void cavities. The glass transition temperature (Tg) of composites increases up to 54–60 °C due to embedded electrospun nanofibers compared to 50 °C for that of epoxy, indicating that fibrous networks may further restrict the intermolecular mobility of matrix in thermal effects. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 618–623 相似文献
19.
A modified sequential extraction method was developed to characterize arsenic (As) associated with different solid constituents in surficial deposits (sediments), which are unconsolidated glacial deposits overlying bedrock. Current sequential extraction methods produce a significant amount of unresolved As in the residual fraction, but our proposed scheme can fractionate >90% of the As present in sediments. Sediment samples containing different As concentrations (3–35 μg g−1) were used to assess the developed method. The pooled amount of As recovered from all the fractions using the developed method was similar (83–122%) to the total As extracted by acid digestion. The concentrations of As in different fractions using the developed scheme were comparable (89–106%) to the As fractions obtained by other existing methods. The developed method was also evaluated for the sequential extraction of other metals such as copper (Cu), cobalt (Co), chromium (Cr) and strontium (Sr) in the sediment samples. The pooled concentrations of these four individual metals from all the fractions were similar (96–104%) to their total concentrations extracted by acid digestion. During method development, we used extractants that did not contain chloride to eliminate formation of polyatomic ions of argon chloride (40Ar35Cl) that interfered with 75As when analyzed using inductively coupled plasma mass spectrometer (ICP-MS). The results suggest that the developed method can reliably be employed for complete As and other metals’ fractionation in sediments using ICP-MS. 相似文献
20.