Sorption of Nickel Ions from Aqueous Solutions by Ion Exchangers

Sorption of Ni²⁺ions from aqueous solutions by ion exchangers differed in their chemical nature and structure was studied. Based on the endothermic curves of ice melting obtained by a differential scanning calorimetry, the amounts of freezing and non-freezing water present in free volumes (pores) of the studied ion exchangers were calculated. Comparison of results obtained from the kinetic curves of nickel ion sorption with data on differential scanning calorimetry indicates a role of structural factor in the sorption of nickel ions. It was found that, depending on the total amount of freezing and non-freezing water, the KU-2-8 sulfonated cationite is the most preferable ion exchanger for the sorption of nickel ions from aqueous solutions. Therefore, sorbent efficiency in this case is determined by its structure rather than by chemical nature.     

Sorption Studies of Nickel ions Onto Sawdust of Dalbergia Sissoo

Sawdust of Dalbergia sissoo, a byproduct of sawmills, was found to be a promising adsorbent for the removal of nickel ions from aqueous solution. Sorption of nickel ions onto sawdust of Dalbergia sissoo was studied using the batch technique. Kinetics studies show that nickel ions sorption process obeys a first order rate law. The applicability of the Langmuir and Freundlich models for the data was tested. Both the models adequately describe the experimental data of the biosorption of nickel ions. The sorption capacities and energies were calculated. Langmuir parameters X_m and K₁ were found to increase with rise in temperature; Freundlich constants 1/n and K_f have been evaluated for 293K, 303K, 313K and 323K. Thermodynamic parameter ΔH° = 4.80 kJ mol^?;1 shows that sorption of nickel ions onto sawdust is an endothermic process.     

Competitive Sorption of Copper and Nickel Ions from Aqueous Solution Using Peat

Bicomponent aqueous solutions of copper and nickel ions have been used to investigate the sorption of metal ions onto peat. Peat, a low cost sorbent, has shown a high capacity for the sorption of single component metal ions attributed to extensive carboxylic acids within its structure. Copper and nickel ions were selected as typical metals in the effluents of electroplating industries. The effects of competitive sorption in batch systems were studied at various metal ion concentrations. In this study the Butler and Ockrent model was modified using a coefficient, . Two models were developed based on the interaction coefficient . The first model incorporates a constant fixed factor for each metal ion into the Butler-Ockrent equation. The second model incorporates a variable factor into the Butler-Ockrent equation; this interaction factor varies as a function of sorbent surface coverage. Predicted equilibrium data are found to be in excellent agreement with experimental values using both modified models for various mole ratios of copper and nickel ions in competitive sorption.     

Sorption of Hexacyanoferrate(II,III) Anions on Nickel(II) Hydroxide

Fe(CN)₆ ^{3 -} and Fe(CN)₆ ^{4 -} anions are sorbed from aqueous solutions of their potassium and cesium salts on -Ni(OH)2 by the mechanism of anion exchange with hydroxy groups. Alkali metal cations (K⁺, Cs⁺) are also partly sorbed on nickel(II) hydroxide in the form of anionic complexes (K,Cs) _z Fe(CN)₆ ^{(n - z)-}, where n = 3 or 4 (0 < z < n). The chemical composition of the new phase appearing in contact of nickel(II) hydroxide with aqueous potassium and cesium hexacyanoferrates(II, III) was determined by X-ray phase analysis and IR spectroscopy.     

Sorption Mechanisms of Eu(3+) on CSH Phases of Hydrated Cements

The sorption mechanisms of Eu(3+) on calcium silicate hydrate (CSH) phases of hydrated cement were investigated as a tool for the prediction of the behavior of trivalent radionuclides with aged/degraded cements in radioactive waste repositories. Four techniques were used: site-selective and time-resolved luminescence spectroscopy, XPS, high-resolution SEM coupled with EDX, and XRD. Results showed that europium is not precipitated in the solution despite its low solubility limit. It is strongly retained on CSH, resulting in a more than 99.8% sorption rate. Two main sorption sites were characterized by luminescence spectroscopy. One site, with a long lifetime, can be interpreted as Eu included in the framework of CSH. Another one, with a shorter lifetime, can be interpreted as a site with a hydrated environment that is high but is less than that of europium hydroxide. It corresponds to superficial complexation or precipitation. Copyright 2001 Academic Press.     

Recovery of Metal Ions by Chitosan: Sorption Mechanisms and Influence of Metal Speciation

Chitosan is characterized by a high affinity for metal ions due to its high content of amine groups. The sorption mechanism depends on both the protonation of these amine groups and the speciation of metal ions. Metal cations may be adsorbed at pH close to neutrality by chelation mechanism while metal anions can be adsorbed in acidic solutions through ionic interactions with protonated amine groups. Several examples are considered. The first example focuses on Cd sorption, which proceeds by a chelation mechanism on free non‐protonated amine groups in neutral media. In acidic solutions the protonation of amine groups limits the ability of amine groups to complex Cd. The cross‐linking of chitosan with glutaraldehyde also results in a dramatic decrease of sorption properties due to the decrease in the density of complexation sites available for sorption. The sorption of vanadium(V) and molybdenum(VI) illustrates the high capacity of chitosan for the sorption of oxo‐anions. They are very efficiently sorbed in acidic solutions by ionic interactions. The correlation of sorption capacities with the distribution of metal species shows that the sorbent has a greater affinity for highly charged anionic species. The sorption of complex anionic species such as chloro‐complexes of Pd and Pt; and that of copper complexed with organic ligands have also been studied. The optimum conditions for sorption are obtained when anionic complexes predominate in the solution. The chemical modification of chitosan, obtained by grafting of sulfur compounds, allows modifying the sorption mechanism: the ion‐exchange polymer is transformed to a dual ion‐exchange and chelating polymer.

Copper sorption isotherm in presence of sodium citrate (0.004 M ) (? RNH: fraction of protonated amine groups; ACuC: total fraction of anionic copper complexes; Cu‐FAL: total fraction of copper‐free anionic ligands).     

Structural Characteristics of the Raney Nickel Promoted by a Platinum-Ruthenium Mixture and Its Electrocatalytic Activity in the Methanol Oxidation Reaction in Alkaline Media

Structural characteristics and electrocatalytic activity in the methanol oxidation reaction in an alkaline solution of the Raney nickel promoted by a platinum-ruthenium mixture are studied with the aid of methods of scanning electron microscopy, x-ray diffraction microanalysis, BET, and measurements of cyclic voltamograms and polarization curves. Distributions of all components of the system under investigation (Al, Ni, Pt, Ru, O) at the surface of the catalyst, the average size of whose particles amounts to 20–30 μm, are established. It is shown that a number of parameters (composition and quantity of the promoting mixture, temperature and concentration of methanol and alkali, amount of the active mass of the electrode) exert an influence on the methanol oxidation rate. The catalyst on the basis of the Raney nickel promoted by 10 wt % Pt/Ru (1/9 at. %) exhibits maximum activity in the methanol electrooxidation reaction in a solution that contains 4 M CH₃OH in 6 M KOH. Upon elevating temperature by 20°C in the temperature interval 40 to 80°C the reaction accelerates by 2–3 times. __________ Translated from Elektrokhimiya, Vol. 41, No. 12, 2005, pp. 1422–1430. Original Russian Text Copyright ? 2005 by Karichev, Tarasevich, Efremov, Bogdanovskaya, Kapustin.     

Sorption and diffusion of gases in a polyimide

Sorption and diffusion of gases (CO₂, N₂, and He) in a polyimide (PI2080) film were measured by using an apparatus which gives the sorption rate curves from the initial state to the equilibrium state. Nonlinear isotherms observed for CO₂ sorption were interpreted successfully in terms of the dual-mode model for sorption in glassy polymers. Linear isotherms observed for N₂ and He seemed to obey Henry's law. Two diffusion coefficients (D_I and D_E) were obtained using the short-time method and the long-time method for a Fickian diffusion model, together with the equilibrium solubility (C_e) from each experiment. The initial sorption rate curves agreed with the calculated curves using D_I, however near sorption equilibrium the curves are in accord with the calculated curves using D_E. These observations suggest that some relaxation process is superimposed on the diffusion process. The non-Fickian transport data were correlated successfully with a model that combines time-dependent diffusion and the Fickian model.     

Sorption of nitrogen oxides in a nonporous crystal

The uptake of various nitrogen oxides was studied with the well known nonporous p-tert-butylcalix[4]arene under ambient conditions.     

The Coordination Structure of the Extracted Nickel(II) Complex with a Synergistic Mixture Containing Lix63 and Versatic10

In the present work, the nickel(II ) synergist complex with isobutyric acid (HL^I ) and 5‐hydroxy‐4‐octanone oxime (HB^I ), which were the corresponding short‐chain analogs of the active synergistic mixture of Versatic10 (HL ) and Lix63 (5,8‐diethyl‐7‐hydroxy‐6‐dodecanoneoxime, HB ), was prepared and studied by single‐crystal X‐ray diffraction (XRD ). The crystal structure of the nickel(II ) synergist complex showed that the composition of the complex was Ni(L^I )₂(HB^I )₂ with a cis ‐form octahedron geometry structure. Both intra‐ and intermolecular hydrogen bonding were observed in the crystal lattice. Compared with the free ligands, similar band shifts of Fourier transform infrared (FT‐IR ) spectra assigned to the stretching vibration of carbon–oxygen single bond (C O), the stretching vibration of carbon–nitrogen double bond (CN), and the disappearance of the scissoring vibration of α‐hydroxy (OH ) were correspondingly found in both the nickel(II ) synergist complex and the extracted nickel(II ) complex in the nonpolar organic phase. Combined with the results from ESI‐MS , XRD , and slope analysis, it was concluded that the major species of the extracted nickel(II ) complex in the nonpolar organic phase might possess a similar coordination structure [Ni(HB )₂(L)₂] as the nickel(II ) synergist complex, along with the neutral complex [Ni(HB )(B)₂].     

Aerogels Based on Calcium Alginate and Silicon Dioxide and Modified with Carbon Nanotubes for Selective Sorption of Argon from a Mixture with Oxygen

Russian Journal of Applied Chemistry - Two kinds of aerogels, those based on silicon dioxide and on calcium aginate, modified with multiwalled carbon nanotubes, were synthesized by the...     

Processes in a Nickel-Zinc Battery with Nickel Oxide Electrode Fabricated from Spherical Nickel Hydroxide

Processes occurring in a cycled nickel-zinc battery with positive nickel oxide electrode fabricated from spherical nickel hydroxide on foamed-nickel support and the influence exerted by its physicochemical parameters on changes in the electrolyte composition and on inter- and intraelectrode mass transfer of zinc was studied.     

Kinetic Models of Batch Sorption in a Limited Volume

Russian Journal of Physical Chemistry A - The batch sorption kinetics described by a nonlinear equation with a variable equilibrium parameter for the interface was considered. It was shown that a...     

Sorption promotors in biopharmaceutics

The absorption of drugs depends on the physico-chemical properties of the constituent substances. Drugs that are absorbed only with difficulty or only slowly, or even not at all, can be made to penetrate into the skin and the mucous membrane (penetration) or to pass through them (permeation) with the aid of “sorption promotors”. The search for substances of this type and the elucidation of their principles of action form part of the field of biopharmaceutics.     

The Deactivation of Nickel Hydroxide to Hypophosphite Electrooxidation on a Nickel Electrode

The deactivation of nickel hydroxide to the electrooxidation of hypophosphite on a nickel electrode was studied by means of in situ UV-Vis subtractive reflectance spectroscopy. The experimental results show that when the potential is lower than -1.0 V (SCE), the surface on nickel electrode is free of nickel hydroxide, on which hypophosphite is active. When the potential moves positively to about 0.75V, two absorbency bands around 300nm and 550nm, which were ascribed to the formation of α-nickel hydroxide, were observed, nickel is oxidized to α-nickel hydroxide. Severe deactivation of the surface occurs when the nickel surface is covered with nickel hydroxide, which separates the hypophosphite ion from nickel substrate.     

Sorption isotherms of Nickel(II), Cobalt(II), Mercury(II), and Lead(II) ions on a phosphorus-containing polymeric sorbent

The influence of the concentration of a complexing ion on the sorption recovery of nickel, cobalt, mercury, and lead ions from aqueous solutions by a phosphorus-containing polymeric polybutadiene-based sorbent was studied. Sorption isotherms of the studied metal ions were processed by the Langmuir and Freindlich models. The affinity of metal ions to the functional groups of a sorbent and the stability of complexes were established to decrease in the order Hg(II) > Pb(II) > Co(II) > Ni(II).     

铒对氢氧化镍电极高温充放电性能的影响

覆Co(Ⅲ)球镍具有优良的电化学性能,是镍氢动力电池较理想的活性材料,然而其高温性能仍待提高.本文研究了通过不同方式在覆Co(Ⅲ)球镍中添加铒改善镍电极的高温性能.结果表明,采用机械混合在球镍中添加1%(原子分数)Er2O3以及表面化学沉积方式在球镍表面包覆1%Er(OH)3的电极70℃时1C充/放电效率分别比无添加的电极提高11.7%和12.6%.循环伏安测试表明,铒的添加提高了镍电极在高温下的析氧过电位,明显提高了电极在高温环境下的充电效率.     

Sorption of a finite amount of swelling solvent in a glassy polymer

We study the time history of a diffusing front when a polymer is exposed to a finite amount of penetrant which becomes used up. A class of polymers is considered for which slow molecular relaxation occurs only at or near the glass-gel interface with instantaneous relaxation both ahead of and behind the progressing front. We show that the position of the penetrant front versus time undergoes a long smooth transition from standard Fickian t^1/2 behavior to exponential time decay onto a final equilibrium position attained when all the penetrant is used up.     

Sorption of tributyltin onto a natural quartz sand

The aim of this study is to understand the sorption of tributyltin (TBT) onto natural quartz sand by classical batch experiments and spectroscopic surface analyses. At pH<6, the major species of TBT is the cation TBT(+). Due to the presence of both the cationic part and the butyl chains, TBT should present amphiphilic properties. For concentrations lower than 40 microM, TBT sorption occurs as a homovalent 1:1 cation exchange between either H(+) or Na(+) and TBT(+). The increasing affinity of TBT with respect to the different materials follows the series kaolinite相似文献