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排序方式: 共有122条查询结果,搜索用时 31 毫秒
1.
The sorptive potential of sunflower stem (180-300 μm) for Cr(III) ions has been investigated in detail. The maximum sorption (≥85%) of Cr(III) ions (70.2 μM) has been accomplished using 30 mg of high density sunflower stem in 10 min from 0.001 M nitric and 0.0001 M hydrochloric acid solutions. The accumulation of Cr(III) ions on the sorbent follows Dubinin-Radushkevich (D-R), Freundlich and Langmuir isotherms. The isotherm yields D-R saturation capacity Xm = 1.60 ± 0.23 mmol g−1, β = −0.00654 ± 0.00017 kJ2 mol−2, mean free energy E = 8.74 ± 0.12 kJ mol−1, Freundlich sorption capacity KF = 0.24 ± 0.11 mol g−1, 1/n = 0.90 ± 0.04 and of Langmuir constant KL = 6800 ± 600 dm3 mol−1 and Cm = 120 ± 18 μmol g−1. The variation of sorption with temperature (283-323 K) gives ΔH = −23.3 ± 0.8 kJ mol−1, ΔS = −64.0 ± 2.7 J mol−1 K−1 and ΔG298k = −4.04 ± 0.09 kJ mol−1. The negative enthalpy and free energy envisage exothermic and spontaneous nature of sorption, respectively. Bisulphate, Fe(III), molybdate, citrate, Fe(II), Y(III) suppress the sorption significantly. The selectivity studies indicate that Cr(III), Eu(III) and Tb(III) ions can be separated from Tc(VII) and I(I). Sunflower stem can be used for the preconcentration and removal of Cr(III) ions from aqueous medium. This cheaper and novel sorbent has potential applications in analytical and environmental chemistry, in water decontamination, industrial waste treatment and in pollution abatement. A possible mechanism of biosorption of Cr(III) ions onto the sunflower stem has been proposed. 相似文献
2.
Dr. Yong Guo Dr. Wengang Li Dr. Jingjing Yan Dr. Basem Moosa Dr. Ma'an Amad Prof. Charles J. Werth Prof. Niveen M. Khashab 《化学:亚洲杂志》2012,7(12):2842-2847
Metal‐free fullerene (C60) was found to be an effective catalyst for the reduction of azo groups in basic aqueous solution under UV irradiation in the presence of NaBH4. Use of NaBH4 by itself is not sufficient to reduce the azo dyes without the assistance of a metal catalyst such as Pd and Ag. Experimental and theoretical results suggest that C60 catalyzes this reaction by using its vacant orbital to accept the electron in the bonding orbital of azo dyes, which leads to the activation of the N?N bond. UV irradiation increases the ability of C60 to interact with electron‐donor moieties in azo dyes. 相似文献
3.
Samaneh Mahmoudi‐GomYek Davood Azarifar Masoumeh Ghaemi Hassan Keypour Masoumeh Mahmoudabadi 《应用有机金属化学》2019,33(6)
A novel Cu (II) Schiff‐base complex immobilized on core‐shell magnetic Fe3O4 nanoparticles (Fe3O4@SPNC) was successfully designed and synthesized. The structural features of these nanoparticles were studied and confirmed by using various techniques including FT‐IR spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy‐dispersive X‐ray spectroscopy (EDS), vibrating sample magnetometer (VSM), X‐Ray diffraction (XRD), wavelength dispersive X‐ray spectroscopy (WDX), and inductively coupled plasma (ICP). These newly synthesized nanoparticles have been used as efficient heterogeneous catalytic system for one‐pot multicomponent synthesis of new pyrano[2,3‐b]pyridine‐3‐carboxamide derivatives. Notably, the catalyst could be easily separated from the reaction mixture by using an external magnet and reused for several successive reaction runs with no significant loss of activity or copper leaching. The present protocol benefits from a hitherto unreported MNPs‐immobilized Cu (II) Schiff‐base complex as an efficient nanocatalyst for the synthesis of newly reported derivatives of pyrano[2,3‐b]pyridine‐3‐carboxamide from one‐pot multicomponent reactions. 相似文献
4.
Ranjbarzadeh Ramin Akhgar Alireza Taherialekouhi Roozbeh DOrazio Annunziata Mohammad Sajadi S. Ghaemi Ferial Baleanu Dumitru 《Journal of Thermal Analysis and Calorimetry》2022,147(13):7509-7521
Journal of Thermal Analysis and Calorimetry - In this research, the effect of using GO/ water nanofluid as a coolant fluid in an isothermal heat transfer system was studied. At first, to evaluate... 相似文献
5.
Mustafa Aghazadeh Mehdi Ghaemi Behrouz Sabour Somayeh Dalvand 《Journal of Solid State Electrochemistry》2014,18(6):1569-1584
Well-dispersed nanoparticles of nickel hydroxide were prepared via a simple electrochemical method. Electrodeposition experiments were performed from 0.005 M Ni(NO3)2 bath at a constant current density of 0.1 mA cm?2 on the steel cathode for 1 h. Recording the potential values during the deposition process revealed that the reduction of water has major role in the base electrogeneration at the applied conditions. The obtained deposit was characterized by the X-ray diffraction (XRD), infrared (IR), differential scanning calorimeter–thermogravimetric analysis, carbon–nitrogen–hydrogen (CHN), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The CHN, XRD, and IR analyses showed that the obtained deposit has α phase of Ni(OH)2 with intercalated nitrate ions in its structure. Morphological characterization by SEM and TEM revealed that the prepared α-Ni(OH)2 is composed of well-dispersed ultrafine particles with the size of about 5 nm. The supercapacitive performance of the prepared nanoparticles was analyzed by means of cyclic voltammetry and galvanostatic charge–discharge tests. The electrochemical measurements showed an excellent supercapacitive behavior of the prepared α-Ni(OH)2 nanoparticles. It was also observed that the α-Ni(OH)2 ultrafine particles have better electrochemical characteristic and supercapacitive behavior than β-Ni(OH)2 ultrafine nanoparticles, including less positive charging potential, lower E a???E c value, better reversibility, higher E OER???E a, higher utilization of active material, higher proton diffusion coefficient, greater discharge capacity, and better cyclability. These results make the α-Ni(OH)2 nanoparticles as an excellent candidate for the supercapacitor materials. 相似文献
6.
G. H. Rounaghi M. Mohajeri M. Doaei A. Ghaemi 《Journal of inclusion phenomena and macrocyclic chemistry》2010,67(3-4):443-450
The complexation reactions between Mg2+, Ca2+ and Sr2+ cations with the macrocyclic ligand, benzo-15-crown-5 (B15C5), in pure acetonitrile, water, methanol and tetrahydrofuran and also in acetonitrile–water (AN–H2O) and in methanol–tetrahydrofuran (MeOH–THF) binary mixtures have been studied at different temperatures using conductometric method. The conductance data show that the stoichiometry of the complexes in most cases is 1:1 [ML]. But in the case of Ca2+ cation a 1:2 [ML2] complex is formed in pure THF, which shows that the stoichiometry of the complexes may be changed by the nature of the medium. The values of stability constants of complexes, which were obtained from conductometric data, show that the stability of complexes is affected by the nature and composition of the binary mixed solvents and a non-linear behavior was observed for variation of logKf of the complexes versus the composition of the solvent systems. The results show that the selectivity order of B15C5 for the metal cations in two AN–H2O binary solutions (mol% AN = 25.71 and 50.94) at 25 °C is: Mg2+ > Sr2+ > Ca2+. The values of thermodynamic parameters (ΔH c 0 , ΔS c 0 ) for formation of complexes were obtained from temperature dependence of stability constants of complexes using the van’t Hoff plots. The results show that the values and also the sign of these parameters are influenced by the nature and also the composition of the binary mixed solvents. 相似文献
7.
Zahra Moulana Mousa Ghaemi Soudabeh Qasemi Khadijeh Ghassemi Mohammad R. Hasanjani Roushan 《高分子科学杂志,A辑:纯化学与应用化学》2017,54(1):30-39
There are many different strategies to decrease the incidence of infection of medical device and food related containers. One way to prevent infection is by modifying the polymers used in making the devices and containers. Incorporation of antimicrobial agents in the bulk material or in formulations of medical devices production has been considered a viable alternative for systemic application of antibiotics. In this article, preparation of a series of triazole containing polymers, poly(triazole-amide-imide)s (PTAI)s and poly(triazole-amide) (PTA)s, and their monomers are reported. These polymers were readily soluble in a variety of organic solvents, showed significant thermal properties and also viscosities in the range of 0.55–0.66 dL/g. They have been tested against a range of Gram-positive and Gram-negative pathogens. The results indicated that these novel polymers containing triazole moiety in their repeating units can effectively control Gram-positive and negative pathogens and their physic-chemical properties besides their antibacterial characteristics make them unique candidate for using in the manufacturing of the medical devices. 相似文献
8.
This paper proves that a difference field (E, ) admits quantifierelimination if and only if E is an algebraically closed field,and is an integer power of the Frobenius automorphism. 1991Mathematics Subject Classification 03C60, 12H10. 相似文献
9.
Ghaemi M.S. Cooney J. Tao J. Lim W.-B. Lonngren K.E. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1990,18(2):249-251
The deposition of an insulating layer upon an aluminum plate in an argon plasma is described. The process is effected in a low-power DC discharge to which a small amount of sulfur hexafluoride (SF6) has been added, causing the formation of anode spots at sharp metallic surfaces. The insulator is deposited in the region beneath the spot 相似文献
10.
Moosa GABELEH 《数学物理学报(B辑英文版)》2014,(5):1661-1669
We study the existence of best proximity points for single-valued non-self map-pings. Also, we prove a best proximity point theorem for set-valued non-self mappings in metric spaces with an appropriate geometric property. Examples are given to support the usability of our results. 相似文献