Preparation and characterization of potassium copper nickel hexacyanoferrate(II) as an ion exchanger for cesium

Potassium copper nickel hexacyanoferrate(II) [KCNF] was prepared by treating potassium nickel hexacyanoferrate(II) with copper nitrate solution in 0.1M HNO₃. The resulting material was dried at various temperatures. Chemical analysis, i.r., thermal decomposition and surface property measurements were used to characterize the material. The adsorption of cesium from aqueous solutions on KCNF was investigated and optimized as a function of equilibration time and pH. The material dried at 110°C was found to be fairly stable in dilute acids, salt solutions, high doses of gamma-radiation and at high temperature. It also showed better surface properties and a high value of ion exchange capacity (2.25 mmol·g^–1) for cesium.     

A new method for preparation of silica potassium cobalt hexacyanoferrate composite ion exchanger from silica sol

A new method for the preparation of porous silicapotassium cobalt hexacyanoferrate (SiO₂ ^.KCoFC) composite from silica sol is described. Silica sol was first gelled with K₄Fe(CN)₆ solution. Then the resulting hydrogel, SiO₂ ^.K₄Fe(CN)₆ was reacted with Co(NO₃)₂ solution in acetone to give the composite SiO₂ ^.KCoFC hydrogel. The empirical formula of KCoFC in the composite was found to be K₁.₆₉Co _0.93Fe(CN)₆. The removal efficiency of the composite for Cs was judged by measuring its distribution coefficient, K _d in 1M HCl solution containing 10 ppm Cs. The K _d of Cs was found to be 5.73^.10⁵ ml/g-composite.     

Sorption of lead(II) on transition metal hexacyanoferrates(II) and on nickel(II)-potassium hexacyanoferrate(II) resin composite in hydrochloric acid medium

Sorption of lead(II) on very poorly soluble hexacyanoferrates(II) of transition metals: Cu^II, Ni^II, Zn^II, Co^II and on the ion-exchange composite obtained by mixing of nickel(II)-potassium hexacyanoferrate(II) with sulfonated phenolic resin serving as matrix was studied. Sorption was performed from solutions of hydrochloric acid at concentrations ranging from 10^–4 to 10^–1 mol·dm^–3. Analytical distribution coefficients for lead(II) sorption on these adsorbents were determined. Lead(II) sorption on Dowex 50 and the composite resin was studied as well.     

Complexing of nickel(II) with 8-mercaptoquinoline and of its 5-derivatives in nickel(II)hexacyanoferrate(II) gelatin-immobilized matrix systems

Complexing processes in systems containing NiII and 8-mercaptoquinoline or its derivatives (5-chloro-, 5-bromo-, 5-phenyl, 5-thiomethyl-8-mercaptoquinoline and 5,8-dimercaptoquinoline) take place in the nick- el(II)hexacyanoferrate(II) gelatin-immobilized matrix (GIM) in contact with an aqueous solution of the corresponding ligand. Under the conditions specified, in the NiII-8-mercaptoquinoline, NiII-5-chloro-8-mer captoquinoline,NiII-5-bromo-8-mercaptoquinoline, NiII-5-phenyl-8-mercaptoquinoline and NiII-5-thiomethyl-8-mercaptoquinoline systems, one water-insoluble complex of NiB2 composition (B– is a singly deprotonated ligand) is formed. In the NiII-5,8-dimercaptoquinoline system, two insoluble complexes, monomeric Ni(HB)2 and polymeric [Ni2B2(H2O)2]n (HB– is the singly, and B2– the doubly deprotonated form of the ligands) are generated. Upon complexing in solution or the solid phase, the formation of only one complex is observed in each of systems cited.     

Adsorption studies of cesium on potassium copper nickel hexacyanoferrate(II) from aqueous solutions

Adsorption of cesium from aqueous solutions on potassium copper nickel hexacyanoferrate(II) (KCNF) has been investigated in batch experiments and optimized as a function of concentration of acids, salts and adsorbate using a radiotracer technique. The results are presented in terms of distribution coefficient, K_d (ml·g^–1). The uptake of cesium obeys a Freundlich adsorption isotherm over the concentration range of 3.7 to 37 mmol·l^–1 with b values of 0.77, 0.68 and 0.56 at temperatures of 293, 313, 333 K, respectively. The Langmuir adsorption isotherm is followed in the concentration range of 15 to 75 mmol·l^–1 in the same temperature range. The values of limiting adsorption concentration (C_m) have been found to be 2.58, 2.44 and 2.32 mmol·g^–1. The heat of adsorption was calculated as 26.43 kJ·mol^–1. The influence of a number of anions and cations on cesium retention has also been studied. Column experiments have been performed and breakthrough have been obtained under different operating conditions. The low cesium capacity of 1.1 mmol·g^–1 has been obtained under dynamic conditions as compared to batch experiments. Desorption of cesium from the column has been achieved (45.4%) by nitric acid solution of 8M concentration at a flow rate of 0.5 ml·min^–1.     

A specific method for the separation of mercury(II) using a weakly basic cellulose ion exchanger

A systematic study of the behavior of many metal ions on the weakly basic cellulose exchanger DEAE in dilute thiocyanate media showed that few metal ions are adsorbed. The adsorption of mercury(II) allows a rapid and highly selective separation from about 40 metal ions. Quantitative results are quoted for the separation of ca. 100 μg of mercury(II) from milligram amounts of other metal ions; 100 μg to 10 mg of mercury(II) can be quantitatively separated from iron(III) in proportions of mercury(II): iron(III) = 100:1 to 1:8,000 on a column containing only 1 g of DEAE.     

Soft template synthesis of (2,8-dithio-3,7-diaza-5-oxanonandithioamide-1,9) nickel(II) and (2,7-dithio-3,6-diazaoctadien-3,5-dithioamide-1,8)nickel(II) using a nickel(II)hexacyanoferrate(II) gelatin-immobilized matrix

Complexing processes leading under specific conditions to nickel(II)hexacyanoferrate(II) gelatin-immobilized matrix systems in contact with aqueous-alkaline solutions (pH12) containing dithiooxamide and formaldehyde or glyoxal, have been studied. It has been shown that template synthesis of macrocyclic co-ordination compounds, (2,8-dithio-3,7-diaza-5-oxanonandithioamide-1,9)nickel(II) and (2,7-dithio-3,6-diazaoctadien-3,5-dithioamide-1,8)nickel(II), occurs. Dithiooxamide, formaldehyde and glyoxal act as ligand synthons in this process.     

Kinetic studies of uranium(VI) adsorption on a composite ion exchanger

In this paper, we studied the continuous adsorption of uranium on a composite ion exchanger. The experimental study was carried out at optimum conditions of uranium uptake found in the previous study. For these conditions first the adsorption isotherm was determined. This isotherm shows non-linear sorption according to the Langmuir model. Then we investigated uranium adsorption at different time intervals at temperatures of 30°C and 60°C, respectively.     

Simultaneous separation and microdetermination of cobalt(II), nickel(II) and copper(II)

 A sensitive and selective flotation procedure for the separation of microamounts of Co(II), Ni(II) and Cu(II) separately or in admixture is described. The maximum separation rate (∼1) for 0.1 mmol/L of each analyte is achieved using 1 mmol/L of both oleic acid (HOL) surfactant and 4-phenylthiosemicarbazide (HPTS) as a collector in the pH range 6–7. A method for the simultaneous separation and microdetermination of the analytes is elaborated, based on adding excess HPTS and floating the species with HOL at pH ∼6. The filtrate (which is clear brownish-yellow) obtained from the scum is used for the spectrophotometric determination of Co(II) at 350 nm. The formation constants of 1:1 and 1:2 [Co(II):HPTS] species are 6.9×10⁵ and 1.22×10¹⁰ L mol^-1, respectively. Beer’s law is obeyed up to 9 μg/mL of Co(II) with a molar absorptivity of 1.15×10⁴ L mol^-1 cm^-1. The precipitate in the scum layer is quantitatively collected, dissolved in aqua regia and aspirated directly into the flame for the (AAS) determination of Ni and Cu. The procedure is successfully applied to some natural water samples. A mechanism for the separation of the analytes is proposed. Received: 23 January 1996/Revised: 1 April 1996/Accepted: 9 April 1996     

Partial purification of neutron-activation 99Mo from cross-contaminant radionuclides onto potassium nickel hexacyanoferrate(II) column

Potassium nickel hexacyanoferrate(II) matrix was prepared and characterized. Purification of neutron-activation ⁹⁹Mo–molybdate(VI) solutes from some residual cross-contaminant radionuclides including ¹³⁴Cs, ⁸⁶Rb, ¹²⁴Sb, ⁶⁰Co and ⁵¹Cr was carried out onto small chromatographic columns of the matrix (each of 1.0 g). Gamma-ray spectrometric analysis data showed that the purification process was not affected by either Mo(VI) concentrations (0.13 and 0.02 M Mo) in the feeding solution of 3.5 M NaNO₃ at pH 9.5 or flow rates (0.2 and 5.0 mL/min) at room temperature. Molybdenum(VI) average loss onto the column matrix did not exceed 7.7 × 10^?2 mmol Mo. Except for ⁵¹Cr, the matrix has very high selectivity for ¹³⁴Cs, ⁸⁶Rb and ¹²⁴Sb with ~50% ⁶⁰Co elimination. The obtained data were briefly discussed.     

Preparation and characterization of nickel hexacyanoferrate films for the removal of cesium ion by electrically switched ion exchange (ESIX)

The method of electrically switched ion exchange (ESIX) involves the sequential application of reduction and oxidation potentials to an ion exchange film to induce the respective loading and unloading of Cs⁺. In this study, four films of nickel hexacyanoferrate were prepared on nickel electrodes with different preparation procedures. Films were characterized by SEM/EDX. Each film shows a different performance with regard to Cs⁺ separation. Scanning electron microscopy was used to characterize the modified film surfaces. Cyclic voltammetry was used to investigate the ion exchange capacity and stability. The four films show a better capacity for Cs⁺ separation compared to previous methods for the deposition of ESIX films. An optimal nickel hexacyanoferrate film was generated when using an applied potential of 0.2 V relative to a saturated calomel electrode (SCE) to generate the nucleation sites, followed by a 1.3 V vs. SCE potential during the growth stage of the film. This film demonstrated the highest film capacity for ion exchange initially (17.3 × 10^?3 C cm^?2) and again after 1000 cycles (11.1 × 10^?3 C cm^?2).     

Adsorption and radiochemical separation of caesium(I) using zirconium phosphate ion exchanger

A rapid and selective method has been developed for the separation of caesium(I) from other metal ions by adsorbing it on zirconium phosphate ion exchanger. Various parameters involved in the quantitative adsorption of caesium(I) on the ion exchanger have been evaluated employing¹³⁷Cs as a tracer.     

Lithium chloride sorption by zinc hexacyanoferrate(II) from a nonaqueous medium

Mechanisms of lithium chloride sorption by zinc hexacyanoferrate(II) Zn₂Fe(CN)₆ · 2.5H₂O in a nonaqueous medium (ethanol) were studied by chemical analysis, X-ray powder diffraction, wide-line ⁷Li and ¹H NMR, vibrational spectroscopy, and impedance spectroscopy. The physicochemical properties of sorption products are reported. Lithium ions in the sorption products were found to be in a hydrated form. The accommodation of molecularly sorbed Li⁺ aq · Cl^? ion pairs in the bores of channels in the crystal structure results in the formation of a continuous network of hydrogen bonds and changes the proton transport mechanism. As the lithium chloride concentration increases in the temperature range 22–150°C, the conductivity (σ) of sorption products increases three to four orders of magnitude to reach 10^?3 S cm^?1.     

Titration of cyanide and hexacyanoferrate(II) with silver nitrate-II Determination of sodium cyanide and sodium hexacyanoferrate(II) in a complexing agent

Cyanide and hexacyanoferrate(II) can be titrated with silver nitrate in the presence of a complexing agent masked with a suitable metal ion. A method for determination of sodium cyanide and sodium hexacyanoferrate(II) in the presence of sodium nitrilotriacetate masked with magnesium ions is given as an example.     

A dimeric high-spin nickel(II) compound with a transition to monomeric tetrahedral nickel(II)

Summary The synthesis and characterisation of dichloro[bis(3,5-dimethylpyrazolyl)methane]nickel(II) s described. At ambient temperature the compound is dimeric with chloro-bridged high-spin five-coordinate Ni^II