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1.
Md. Sayem Alam A. Mohammed Siddiq 《Journal of Dispersion Science and Technology》2016,37(9):1287-1293
Herein, we report the micellization and the clouding of a nonionic surfactant, poly(ethylene glycol) t-octylphenyl ether (Triton X-100), in aqueous solutions in the absence and presence of (chloride salt) electrolytes. In the absence and presence of electrolytes, the critical micelle concentration (CMC) of Triton X-100 was measured by surface tension measurements. Upon increasing the temperature as well as the concentration of electrolytes, the CMCs decreased. The surface properties and the thermodynamic parameters of the micellar systems were evaluated. From these evaluated thermodynamic parameters, it was found that in the presence of an electrolyte, the stability of the micellar system is high. The cloud points (CPs) of Triton X-100 were also measured in the absence and presence of metallic ions of electrolytes. Upon the addition of metallic ions of chloride salts (electrolytes), the decrease in CP values was observed and the order was found to be: K+ > Na+ > Li+ > NH+4. 相似文献
2.
J. P. Shukla M. S. Nagar M. S. Subramanian 《Journal of Radioanalytical and Nuclear Chemistry》1981,62(1-2):61-72
Solvent extraction behaviour of Am(III) from dilute nitric acid media with sulfoxides (R2SO) in Solvesso-100 has been investigated over a wide range of conditions. Very poor extractability of Am necessitated the
use of salting-out agents, viz., nitrates of Al, Mg, Ca, Li and NH
4
+
. Effects of certain variables such as acidity, extractant concentration, saltingout agent, temperature etc., on metal extraction
by sulfoxides have been examined systematically. For a fixed sulfoxide concentration, extraction attains a maximum value up
to around 0.2–0.4M HNO3 and decreasing above 1M HNO3. In contrast, increasing the concentration of sulfoxide (0.8M DISO, 1.3M DBuSO) gives almost quantitative Am extraction up
to 1M HNO3. For satisfactory extraction, di-n-octyl as well as di-n-hexyl sulfoxide are the most suitable extracting agents. Extractability
of Am increases with increasing amounts of all the salting-out agents studied and their effect follows the sequence: Al3+>Mg2+>Ca2+>Li+>NH
4
+
; this is also the relative dehydrating effect of the cations. The species extracted would appear to be Am(NO3)3.3R2SO. Americium is easily stripped with 1–3M HNO3 solutions from the loaded organic phase. Extraction decreases with increasing temperature, indicating the extraction to be
exothermic. Extraction from partially non-aqueous solutions was also investigated. 相似文献
3.
Conductance behaviour of a microporous membrane and the application of absolute reaction rate theory
《Journal of membrane science》1987,31(1):89-102
The membrane conductance of a microporous membrane prepared by the hydrogen peroxide (5%) treatment of ion-exchange membranes of the ‘Neosepta’ family has been studied at different temperatures. The membranes were bathed in some common uni-univalent chloride solutions at different concentrations. In general, the membrane conductance, in the temperature range studied, shows values increasing more or less linearly with increases in concentration, but tends towards limiting values at higher concentrations. The magnitudes follow the order K+ > NH4+ ≥ Na+ > Li+, which is the reverse order of the hydrated sizes of these ions. The temperature variations of the conductance have been utilised to calculate the activation parameters, Ea, ΔH3, ΔG3 and ΔS3, assuming the applicability of the theory of absolute reaction rate. The activation energies for conduction increase in the order K+ < NH4+ ≤ Na+ < Li+, which is the reverse of the order of conductances but the same as the sequence of the hydrated sizes of the cations. For a particular electrolyte solution, the energy values decrease with increasing concentrations of the bathing electrolyte. The ΔS3 values are found to be mostly very small positive quantities, indicating that virtually neither any bond formation nor any loss of membrane structure takes place during the permeation process. 相似文献
4.
A. Survila Z. Mockus S. Kanapeckaite J. Pileckiene G. Stalnionis 《Russian Journal of Electrochemistry》2011,47(2):129-135
The kinetics of cathodic processes proceeding in the acidic 0.01 M Cu(II) solutions containing gluconic acid and 0.5 M Na2SO4 as the supporting electrolyte is studied. According to the spectrophotometric data, in the moderately acidic solutions, a
monoligand complex of CuL+ predominantly forms. Its concentration stability constant is 102.2 M−1. In the cathodic voltammograms, a well-defined plateau of the limiting current is observed. The height of the plateau obeys
the Levich equation. The effective diffusion coefficient decreases from 4.2 × 10−6 to 2.5 × 10−6 cm2/s with increasing complexation degree of the system. An analysis of normalized Tafel plots showed that the exchange current
density of Cu2+ + e → Cu+ process decreases with increasing concentration of ligand or with increasing pH value. Thereby, the cathodic chargetransfer
coefficient remains constant (0.33 ± 0.02). A comparison of the kinetic data with the results of deposit surface examination
points to significant surface activity of the ligand. The gluconate chemisorption can be accompanied by the incorporation
of the fragments, which were formed as a result of its destruction, into the electrodeposits. 相似文献
5.
R.M. Pashley 《Advances in colloid and interface science》1982,16(1):57-62
The forces between two molecularly smooth mica surfaces were measured over a range of concentrations in aqueous Li+, Na+, K+ and Cs+ chloride solutions. Deviations from DLVO forces in the form of additional short-range repulsive “Hydration” forces were observed only above some critical bulk concentration, which was different for each electrolyte. These observations are interpreted in terms of the corresponding ion exchange properties at the mica surface. “hydration” forces apparently arise when hydrated cations adsorbed on mica are prevented from desorbing as two interacting surfaces approach. dehydration of the cations leads to a repulsive hydration force. A simple site-binding model was successfully applied to describe the charging behavior of interacting mica surfaces . By subtraction of the DLVO-regulation theory from the total measured force the net hydration force was obtained for mica surfaces apparently fully covered with adsorbed cations. The magnitude of this extra force followed the series Na+ > Li+ > K+ > Cs+ and, in each case, could be described by a double-exponential decay. 相似文献
6.
Viscosities for aqueous NH4Cl and tracer diffusion coefficients for22Na+,36Cl–, HTO, and CH3OH, acetone and dimethylformamide (all14C-labelled) in NH4Cl supporting electrolyte are reported for 25°, together with tracer diffusion coefficients for22Na+,36Cl–, and14CH3OH in 1M KI, and for14CH3OH in 1M MgCl2. The diffusion coefficient of HTO in NH4Cl solutions is slightly larger, for most of the concentration range investigated (0.05 to 4.5 M), than the value for pure water and is almost unaffected by the supporting electrolyte up to about 4M. Similar behavior is shown by CH3OH, acetone and dimethylformamide in NH4Cl solutions. Onsager limiting law behavior is approached by Cl– at NH4Cl concentrations in the 0.05–0.1M region but at much lower concentrations by Na+. 相似文献
7.
Shabana Taj Din Muhammad M. Ashraf Chaudhry Muhammad Mazhar 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(1):79-88
Potassium iron(III) hexacyanoferrate(II) supported on poly methyl methacrylate, has been developed and investigated for the
removal of lithium, rubidium and cesium ions. The material is capable of sorbing maximum quantities of these ions from 5.0,
2.5 and 4.5 M HNO3 solutions respectively. Sorption studies, conducted individually for each metal ion, under optimized conditions, demonstrated
that it was predominantly physisorption in the case of lithium ion while shifting to chemisorption with increasing ionic size.
Distribution coefficient (K
d) values followed the order Cs+ > Rb+ > Li+ at low concentrations of metal ions. Following these findings Cs+ can preferably be removed from 1.5 to 5 M HNO3 nuclear waste solutions. 相似文献
8.
R. Kopunec F. macášek P. Rajec D. Hudecová 《Journal of Radioanalytical and Nuclear Chemistry》1979,51(2):401-405
Sorption of macroamounts of the technetium thiourea complex cation by a cation exchange resin was studied in HNO3 and HClO4 solutions as a function of the concentration and reaction time for pertechnetate with thiourea. The distribution ratio reaches
the value of 103 and may be even higher (>104) when sorption proceeds from a solution of the solid complex in dilute perchloric acid. The complex cation is extracted from
0.25–1M HNO3 with solutions of the bis(1,2-dicarbollyl)cobalt(III) anion in nitrobenzene—chloroform (1:1), log D=2.75−2.95 being obtained.
The preconcentration and separation of technetium on cation exchangers from dilute mineral acids would seem to be one field
of application. 相似文献
9.
The rate of the hexacyanoferrate redox system shows a first order dependence on the concentration of the cationic component of the supporting electrolyte. The catalytic influence of the alkali metal cations on the electrode process increases in the order Li+<Na+<K+~Cs+. The temperature dependence of the rate constant of the electrode process in KF and LiNO3 has been measured and the results show that the activated complex is formed by the collision or association of a cation of the supporting electrolyte with the reactant anion, which may already be paired with one cation. It is suggested that this mechanism may be applicable to other electrode reactions involving highly charged species. 相似文献
10.
The transference of water that results from ion migration through the nickel hydroxide precipitate membrane was studied in chloride, perchlorate, nitrate, and sulphate solutions to estimate the transference number of water and the co-ion transport. In the systems of univalent anions, the moles of water transported per mole of electrons in 0.1 N solutions is almost identical to the hydration number of each anion. This water flow decreases gradually as the concentration of external solution increases, because of increase in the co-ion (cation) transport with increasing concentration of the solution. In the system of sulphate solutions the co-ion transport is remarkable, the transport number of Na+ ions being 0.03 in 0.01 N, 0.27 in 0.10 N, and 0.50 in 0.5 N Na2SO4 solution. This large co-ion transport in Na2SO4 solution is attributed to the partical replacement of hydroxyl groups on the membrane by SO2?4 ions, which then acts as a negative fixed charge. The order of the selectivity for co-ion transport is K+ > Na+ > Li+ > Ni2+ ? Mg2+ in sulphate solutions and also in chloride solutions, although the transport number of the cations is much smaller in chloride solution than in sulphate solution. 相似文献
11.
I. C. Pius M. M. Charyulu C. K. Sivaramakrishnan S. K. Patil 《Journal of Radioanalytical and Nuclear Chemistry》1994,187(1):57-65
Distribution ratios of Pu(IV) between 7.5M HNO3+0.75M H3PO4+0.3M H2SO4 media and a macroporous anion-exchange resin Amberlyst A-26 (MP) increased from 40 to 250 when 1M aluminium nitrate was added to the aqueous medium. When 1M ferric nitrate was used in place of aluminium nitrate the distribution ratio further increased to 850. The 10% Pu(IV) breakthrough capacities with a 5 ml bed resin column, using synthetic feed solutions containing 1M aluminium nitrate, were 1.4 g l–1, 3.2 g l–1 at flow rates of 30 ml per hour and 10 ml per hour, respectively. The corresponding 10% Pu(IV) breakthrough capacities in the presence of 1M ferric nitrate were 8.5 g l–1 and 12.8 g l–1. More than 97% of plutonium could be recovered from actual analytical phosphate waste solutions. 相似文献
12.
J. Lielmezs 《Thermochimica Acta》1977,19(3):249-266
The observed external transverse magnetic field effect on electrolyte diffusion in diamagnetic alkali chloride (LiCl, NaCl; KCl and CsCl)-water solutions, expressed as the fractional arithmetic average integral diffusion coefficient, *=[(?0H > -<0 > )/<0 > ;]×102; has been correlated with structural (hydration number, viscosity and ionic limiting equivalent conductance) and microdynamical (proton nuclear magnetic relaxation times and proton nuclear magnetic resonance shifts) parameters expressing the configurational rearrangement modes of the solvent and solute molecules forming the aqueous solution. 相似文献
13.
D. R. Ghadse D. M. Noronha I. C. Pius M. M. Charyulu A. R. Joshi C. K. Sivaramakrishnan 《Journal of Radioanalytical and Nuclear Chemistry》1996,213(3):225-232
Sorption of Pu(IV) from hydrochloric acid-oxalic acid solutions has been investigated using different anion exchangers, viz., Dowex-1X4, Amberlite XE-270 (MP) and Amberlyst A-26 (MP) for the recovery of plutonium from plutonium oxalate solutions. Distribution ratios of Pu(IV) for its sorption on these anion exchangers have been determined. The sorption of Pu(IV) from hydrochloric acid solutions decreases drastically in the presence of oxalic acid. However, addition of aluminium chloride enhances the sorption of plutonium in the presence of oxalic acid, indicating the feasibility of recovery of plutonium. Pu(IV) breakthrough capacities have been determined with a 10 ml resin bed of each of these anion exchangers at a flow rate of 60 ml per hour using a solution of Pu(IV) with the composition: 6M HCl+0.05M HNO3+0.1M H2C2O4+0.5M AlCl3+100 mg.l–1 Pu(IV). The 10% Pu(IV) breakthrough capacities for Dowex-1X4, Amberlite XE-270 (MP) and Amberlyst A-26 (MP) are 15.0, 8.9 and 6.2 g of Pu(IV) l–1 of resin respectively. 相似文献
14.
H. F. Aly E. S. Zakaria S. A. Shady I. M. El-Naggar 《Journal of Radioanalytical and Nuclear Chemistry》1999,241(2):331-336
Cerium(IV) antimonate was prepared by dropwise addition of 0.6M antimony pentachloride and 0.6M cerium ammonium nitrate solutions
by a molar ratio of Ce/Sb 0.75. Exchange isotherms for H+/Co2+, H+/Cs+, H+/Zn2+, H+/Sr2+ and H+/Eu3+ were determined at 25, 40 and 60°C. Besides, it was proved that europium is physically adsorped, while zinc, strontium, cobalt
and cesium are chemically adsorbed. Moreover, the heat of adsorption of zinc, strontium, cobalt and cesium on cerium (IV)
antimonate was calculated and indicated that cerium(IV) antimonate is of endothermic behavior towards these ions. Also the
distribution coefficients of these ions were determined and it was found that the selectivity is in the order: Eu3+>Sr2+>Cs+>Na+. 相似文献
15.
Chelating resins are used for preconcentrating metal ions in trace analysis. As part of a systematic study of sorption characteristics
of the chelating resin Chelex 100, the sorption of Zn(II) and Cd(II) in different aqueous media was investigated. The distribution
coefficient (DC) values for both Zn(II) and Cd(II) were extremely low (<4) in 0.5 to 6M HNO3 and H2SO4 solutions. In HCl solution, theDC values for both Zn(II) and Cd(II) were higher, reaching a peak of nearly 40 in 3M HCl solutions. TheDC values for both Zn(II) and Cd(II) increased with increasing pH in chloride, nitrate, and sulfate solutions (0.1M); the value
was nearly 104 for both Zn(II) and Cd(II) between pH 5 and 7 and pH 6 and 8, respectively. 相似文献
16.
The results of studies concerning two- and three-phase systems in an agitated vessel are presented. The aim of our research
was to investigate the effect of the physical properties of the liquid phase on the value of the volumetric gas-liquid mass
transfer coefficient in mechanically agitated gas-liquid and gas-solid-liquid systems. Our experimental studies were conducted
in a vessel with an internal diameter of 0.288 m. The flat bottom vessel, equipped with four baffles, was filled with liquid
up to a height equal to the inner diameter. The liquid volume was 0.02 m3. Three high-speed impellers of a diameter equal to 0.33 of the vessel diameter were used: Rushton turbine (RT), Smith turbine
(CD 6), or A 315 impeller. The measurements were carried out in coalescing and non-coalescing systems. Distilled water and
aqueous solutions of an electrolyte (sodium chloride) of two different concentrations were used as the liquid phase. The gas
phase was air. In the three-phase system, particles of sea sand were used as solid phase. The measurements were conducted
at five different gas-flow rates and three particle loadings. Volumetric gas-liquid mass transfer coefficients were measured
using the dynamic method. The presence and concentration of an electrolyte strongly affected the value of the gas-liquid mass
transfer coefficient in both two- and three-phase systems. For all agitators used, significantly higher k
l
a coefficient values were obtained in the 0.4 kmol m−3 and 0.8 kmol m−3 aqueous NaCl solutions compared with the data for a coalescing system (with distilled water as the liquid phase). The k
l
a coefficient did not exhibit a linear relationship with the electrolyte concentration. An increase in the sodium chloride
concentration from 0.4 kmol m−3 to 0.8 kmol m−3 caused a considerable decrease in the volumetric mass transfer coefficient in both the two-phase and three-phase systems.
It was concluded that the mass transfer processes improved at a certain concentration of ions; however, above this concentration
no further increase in k
l
a could be achieved. 相似文献
17.
Iwao Satake Masao Fukuda Tomohisa Ohta K
zaburo Nakamura Noboru Fujita Akira Yamauchi Hideo Kimizuka 《Journal of Polymer Science.Polymer Physics》1972,10(12):2343-2354
Counterion activity coefficients in solutions of dextran sulfate with and without added salts were determined potentiometrically by using a cation-exchange membrane and a sodium glass electrode. Dextran sulfate was shown to interact with monovalent cations in the order of preference: K+ > Cs+ > Na+ > Li+, whereas no specificity was found for bivalent cations. On the basis of light-scattering measurements, the expansion of the dextran sulfate polyion in solutions of alkali metal salts was found to fall in the same order as the counterion activity coefficients in salt-free solutions. It was also shown that the dextran sulfate polyion assumes a more extended conformation in magnesium chloride solution than in calcium chloride. These results were substantiated by measurements of solution viscosities. 相似文献
18.
A new approach to expand the accessible voltage window of electrochemical energy storage systems, based on so-called “water-in-salt” electrolytes, has been expounded recently. Although studies of transport in concentrated electrolytes date back over several decades, the recent demonstration that concentrated aqueous electrolyte systems can be used in the lithium ion battery context has rekindled interest in the electrochemical properties of highly concentrated aqueous electrolytes. The original aqueous lithium ion battery conception was based on the use of concentrated solutions of lithium bis(trifluoromethanesulfonyl)imide, although these electrolytes still possess some drawbacks including cost, toxicity, and safety. In this work we describe the electrochemical behavior of a simple 1 : 1 electrolyte based on highly concentrated aqueous solutions of potassium fluoride (KF). Highly ordered pyrolytic graphite (HOPG) is used as well-defined model carbon to study the electrochemical properties of the electrolyte, as well as its basal plane capacitance, from a microscopic perspective: the KF electrolyte exhibits an unusually wide potential window (up to 2.6 V). The faradaic response on HOPG is also reported using K3Fe(CN)6 as a model redox probe: the highly concentrated electrolyte provides good electrochemical reversibility and protects the HOPG surface from adsorption of contaminants. Moreover, this electrolyte was applied to symmetrical supercapacitors (using graphene and activated carbon as active materials) in order to quantify its performance in energy storage applications. It is found that the activated carbon and graphene supercapacitors demonstrate high gravimetric capacitance (221 F g−1 for activated carbon, and 56 F g−1 for graphene), a stable working voltage window of 2.0 V, which is significantly higher than the usual range of water-based capacitors, and excellent stability over 10 000 cycles. These results provide fundamental insight into the wider applicability of highly concentrated electrolytes, which should enable their application in future of energy storage technologies.The stability of water-in-salt electrolyte systems is investigated using highly concentrated solutions of KF(aq) with graphite as a model system. 相似文献
19.
Liquid membrane electrodes based on ion-association extraction systems responding to the ammonium ion are described. The tris(2-nitroso-4-chlorophenol)iron(II) anion in a nitrobenzene solution gives an electrode exhibiting Nernstian response in the range 1–10-4 M ammonium ion (slope, 60 mV) in solutions of pH 4–9. The order of the selectivity coefficients (Kij) is N(CH3)+4 > NH(CH3)+3 > NH2(CH3)+2 > NH3CH+3 > K+ > NH+4 > Na+ > Li+. 相似文献
20.
The adsorption of cesium on manganese dioxide from aqueous solutions has been studied in relation to pertinent variables such as shaking time, pH, composition of aqueous solutions, mass of adsorbent (10 mg–1 g) and concentration of adsorbate (10–6–5·10–3 M), using a radiotracer technique. The influence of various anions and cations on cesium adsorption was examined. The distribution coefficient of a variety of other elements was determined under similar conditions. The adsorption of cesium obeys a Freundlich-type isotherm over the entire concentration range investigated, whereas the Langmuir-type isotherm is followed only at moderate concentrations. 相似文献