Inorganic Cation Exchanger Research Articles

Zirconium Succinophosphate- A New Inorganic Cation-exchanger

Zirconium Succinophosphate- A New Inorganic Cation-exchanger

ChemInform Abstract: Synthetic Carbonate Apatites as Inorganic Cation Exchangers. Exchange Characteristics for Toxic Ions.

AbstractThe ion exchange characteristics of B‐type carbonate apatites (CAP) containing 6 or 16 wt.% CO32‐ ions, for Zn2+, Cd2+, Hg2+, and Pb2+ in aqueous solution at 25 °C are investigated at 25 °C and compared with those of CO32‐‐free hydroxyapatite.

Synthetic Hydroxyapatites as Inorganic Cation-Exchangers; Exchange Characteristics for Pb2+ and Sn2+ Ions in Acidic Solution

Abstract The cation-exchange characteristics between Pb2+ ions of aqueous solutions containing counter-anions (F−, C1−) and Ca2+ ions of synthetic hydroxyapatite samples have been investigated in detail under the conditions of low pH values (3.0, 4.0 and 5.0) by a normal batch method. Even at the low pH value of 3.0 the apatite structure in a solution containing F− or C1− ions was maintained via a concurrent ion-exchange effect of Pb2+ ions together with F− or C1−ions, which are known to be exchangeable with OH- ions of the apatite. Moreover, it was found that Ca2+ ions in the apatite sample can easily be exchanged for Pb2+ ions almost without distinction between MI and M2 sites, assisted by the loosening effect of protons even at room temperature. Next, it was found that the hydroxyapatite samples are transformed into amorphous states by the reactions between Ca 2+ ions in the samples and Sn 2+ ions in the SnC12 acidic aqueous solutions with pH of 3.0 or below with a molar ratio of Sn2+/Ca2+ -1.0. The ex...

Synthetic carbonate apatites as inorganic cation exchangers. Exchange characteristics for toxic ions

The ion-exchange characteristics between Ca2+ ions in carbonate apatites containing 6 and 16 wt % CO2–3 ions and toxic ions (Zn2+, Cd2+, Hg2+, and Pb2+) in aqueous solution have been investigated in detail at 25 °C. From the results, it was found that the ion-exchange removal characteristics for Zn2+, Cd2+ and Pb2+ ions were enhanced with increasing CO2–3 ion content; however, those for Hg2+ ions were similar for different CO2–3 content. The reaction with Pb2+ ions was especially remarkable and formed Pb2+ ion-exchanged carbonate apatites. The effect of substitution of CO2–3 for PO3–4 ions was concluded to be a loosening effect on the skeletal structure of the apatite.

Synthetic Hydroxyapatites as Inorganic Cation-Exchangers; Exchange Characteristics for Pb2+ and Sn2+ Ions in Acidic Solution

Abstract The cation-exchange characteristics between Pb2+ ions of aqueous solutions containing counter-anions (F−, C1−) and Ca2+ ions of synthetic hydroxyapatite samples have been investigated in detail under the conditions of low pH values (3.0, 4.0 and 5.0) by a normal batch method. Even at the low pH value of 3.0 the apatite structure in a solution containing F− or C1− ions was maintained via a concurrent ion-exchange effect of Pb2+ ions together with F− or C1−ions, which are known to be exchangeable with OH- ions of the apatite. Moreover, it was found that Ca2+ ions in the apatite sample can easily be exchanged for Pb2+ ions almost without distinction between MI and M2 sites, assisted by the loosening effect of protons even at room temperature. Next, it was found that the hydroxyapatite samples are transformed into amorphous states by the reactions between Ca 2+ ions in the samples and Sn 2+ ions in the SnC12 acidic aqueous solutions with pH of 3.0 or below with a molar ratio of Sn2+/Ca2+ -1.0. The existence of hydroxyapatite as amorphism in acidic aqueous solutions such as SnC12 is quite interesting, because in general the hydroxyapatite has been found to be dissolved in acidic aqueous solutions. Moreover, the obtained amorphism are found to be stable up to at least 500 to 6OO°C but to be unstable in alkaline solutions. The characteristics of Sn2+ ions are found to have been found to form crystalline Pb 2+ apatite even in be quite different from those of homologous Pb2+ ions which have been found to form crystalline pb2+ apatite even in such an acidic atmosphere.

Synthetic hydroxyapatites as inorganic cation exchangers. Part 3.—Exchange characteristics of lead ions (Pb2+)

The ion-exchange characteristics between Pb2+ ions of aqueous solutions containing various counter-anions (F–, Cl– and NO–3) and Ca2+ ions of synthetic hydroxyapatite samples have been investigated in detail under the conditions of low pH values (3.0, 4.0 and 5.0).The ratio of removal of Pb2+ ions to the apatites increased with a decrease in pH from 5.0 to 3.0, but even at pH 5.0 the ratio of removal of Pb2+ ions increased from 10 to 60% as the reaction time increased from 2 h to 20 days.Even at the low pH value of 3.0 the apatite structure in a solution contaning F– or Cl– ions was maintained via a concurrent ion-exchange effect of Pb2+ ions together with F– or Cl– ions, which are known to be exchangeable for OH– ions of the apatite, while the apatite structure in the system containing NO–3 ions was destroyed by protons. This destruction is thought to be due to the fact that since NO–3 ions cannot be exchanged for OH– ions, the retention of the apatite structure together with Pb2+ ions was made impossible by the loosening or dissolving effect of protons on the skeletal structure of the apatite at such a low pH as 3.0.Moreover, the crystal structure of Pb2+ ion-exchanged apatite [Ca3.6Pb6.4(PO4)6(OH)2], with a= 9.882(3)A and c= 7.417(2)A, has been investigated by the X-ray powder pattern-fitting method. The determined site occupancy factors of Pb2+ ions were almost the same, i.e. 0.75 and 0.57 for M1 and M2 (column site) sites, respectively.These results show that Ca2+ ions in the apatite sample can easily be exchanged for Pb2+ ions almost without distinction between M1 and M2 sites, assisted by the loosening effect of protons even at room temperature. The hydroxyapatite can easily be converted into stable lead apatite in acidic solutions containing exchangeable anions such as F– or Cl– by a synergistic effect.

Synthetic hydroxyapatites as inorganic cation exchangers. Part 2

The removal of [graphic omitted] h as Pb2+, Mn2+, Co2+ and Cu2+ in aqueous solution by four synthetic hydroxyapatites (S-1, S-2, S-3, S-4) has been investigated using both batch and column methods. The removal is due not only to an adsorption effect but also to an ion-exchange reaction between the cations in solution and the Ca2+ ions of the apatites. The order of the ions according to the amount exchanged was as follows: Pb2+ > Cu2+ > Mn2+≃ Co2+. Pb2+ ions were readily removed by the apatites and the maximum value for the exchange of Pb2+ ions was 230 mg per g of S-4 apatite. The apatites, particularly S-4, would seem to be possible agents for the removal of toxic Pb2+ ions. The selectivity of the apatites for the cations can be explained by considering the radii and the electronegativities of the ions.

Synthetic hydroxyapatites employed as inorganic cation-exchangers

The manner in which ions such as Cd2+, Zn2+, Ni2+, Mg2+ and Ba2+ in aqueous solution are removed by synthetic hydroxyapatites has been probed by using both batch and column methods. The behaviour is not merely an adsorption effect but a type of ion-exchange reaction between the ions in solution and the Ca2+ ions of the apatites. The ranking of the ions according to amount exchanged was as follows: Cd2+, Zn2+ > Ni2+ > Ba2+, Mg2+. These results suggest that the apatites have a selectivity for metallic cations and can be employed as a new inorganic cation-exchanger for recovering valuable ions in waste water.

The quantity-intensity relations of potassium in soils from plots having nine fixed crop rotations for six years

Soil samples collected 6 years after raising of various cereals, pulses, oil seed and tuber crops in nine fixed rotations were used to study the quantity-intensity relations of potassium. Potassium activity ratio, where the soil neither gains nor looses K, was correlated in a highly significant manner (P = 0.01) with the total amount of K fertilizer applied during 6 years. The K buffering capacity, the slope of the Q/I curve, when the soil neither gains nor looses K, was positively correlated (P = 0.05) with K saturation of the total and inorganic cation exchange capacities to a similar extent. Superimposing Q/I curves showed no appreciable difference between samples from different treatments. Desorption of potassium with increasing soil∶solution (0.01M CaCl2) ratio followed a Langmuir type of equation and supported the conclusions drawn from quantity-intensity curves.

Thin-layer chromatographic separation of platinum metals on a semi-crystalline inorganic ion-exchanger

Thin layers of the semi-crystalline form of stannic arsenate, an inorganic cation-exchanger, have been used for chromatography of the noble metals. Fast and selective separations of micro quantities of osmium and base metals from other noble metals have been developed. Important ternary and quaternary separations of platinum metals have also been developed and are reported. The behaviour of noble metals in ammonia solutions (0.5–5.0M) has also been studied and is discussed.

Sorption properties of zirconium phosphate prepared by the sol-gel method

The conversion of zirconium hydroxide, prepared by the sol-gel method in the form of spherical particles, to the zirconium phosphate, applicable as an inorganic cation exchanger, has been studied. The uptake of phosphoric acid on the zirconium hydroxide hydrogel and xerogel in static, as well as dynamic, conditions and the effects of the preparative methods for the initial zirconium hydroxide gel, phosphoric acid concentration and the conversion time, upon the ion exchange properties of the zirconium phosphate have been investigated.

Studies on ligand-exchange chromatography : V. Gas chromatographic separation of lower aliphatic amines by ligand exchange

In the ligand-exchange gas chromatographic separation of lower aliphatic amines developed, an inorganic cation exchanger (zirconium phosphate) in the Cu 2+ form is used as the stationary phase, and the mobile phase is nitrogen gas containing ammonia and water vapour. By studying the effects of the structures of the amines, the cation of the stationary phase and the composition of the mobile phase on the retention values, it has been found that the amine-stationary phase interaction is correlated with the stability of the complexes formed and with steric effects on the amine-metal ion reaction. The concentration of ammonia in the mobile phase also plays an important part in determining retention times and peak resolution.

The separation of some Bi- and tervalent cations on zirconium phosphate columns

On small columns filled with the inorganic cation-exchanger zirconium phosphate, Zn2+-Cd2+ were quantitatively and Ni2+-Co2+ partly separated. The exchanger was in the NH4+ form, and 0.5–4N NH4Cl served as eluent. With the exchanger in the H+ form, U02 2+ was separated from bivalent cations and ferric iron by stepwise elution with 0.1, 0.5 and 4N HCl solutions.

Inorganic pH Dependent Cation Exchange Charge of Soils

AbstractSodium hydroxide titration curves were determined on H resin treated montmorillonite, untreated acid and neutral soils of different origins and on the same soils with an H resin treatment. The acid montmorillonite titration curve reveals four buffer ranges corresponding to hydronium ions (range I), monomelic trivalent aluminum ions Range II), and two pH dependent charge ranges. Untreated acid soils contained pH dependent buffer zones governed jointly by the organic fraction, the soil pH, the presence of monomeric trivalent aluminum, and the exchange blocking mechanisms of other cations. Following an H resin treatment, soils containing less than 2 per cent of organic matter exhibited a clearly defined third buffer range (Range III) from pH 5.5 to 7.6. The inflection points are masked in the pH dependent buffer range in soils containing more than 2 per cent organic matter. The presence of added aluminum increased the pH dependent charge in an acidified montmorillonite while added ferric iron slightly decreased it. The natural acid weathering processes in soils result in some blocking of pH dependent charge as in Dodge soil of Wisconsin (KCl pH 4.5). When greater acidity develops, a large pH dependent charge results, as in Coolville soil in Ohio (KCl pH 4.0), and the lime requirement of the soil thus increases greatly.

A fundamental study on the ion exchange separation of lithium, nitrogen and uranium isotopes

Fundamental equations for the ion exchange separation factor of the isotopes A and B are derived : a)for the system having the molecules or ion associations[math] b)for the system having stepwise series of complexes[math] According to the prediction based on these fundamental equations, some experimental works have been done to obtain larger separation factors for the isotopes Li, N and U. The results are as follows : a)[math]1,005-1,008 for the system of a weaker electrolyte, LiOH, in the external solution with the strongly acidic and very highly cross-linked cation exchange resins. The separation factor reaches 1,012 when acetone is added to the same system to reduce the dissociation constant of LiOH. 1,013-1,015 for the system of strong electrolyte, LiCL, in the external solution with the weakly acidic inorganic cation exchanger, Ionite C (zirconium phosphate typ). 1,016 for the system of LiOH in the aqueous external solution with Ionite C. The value 1,022 is obtained by adding acetone to the same system. b)[math]1,027-1,029 for the system of weak electrolyte, NH3 , in the external aqueous solution either with strongly acidic cation exchange resins or with Ionite C. The addition of organic solvent such as ethanol or acetone gives better results especially with very highly cross-linked cation exchange resins. c)[math]The values 1,000 28-1,000 40 are estimated from break through experiments with hydrochloric acid solutions containing greater part of uranous together with smaller part of uranyl ions.

The Microdetection of Uranium with an Inorganic Cation Exchanger

The Microdetection of Uranium with an Inorganic Cation Exchanger