Sorption of phosphorus(V) by polymeric sorbents based on aminopolystyrene and 4-amino-<Emphasis Type="Italic">N</Emphasis>-azobenzenesulfamide

Phosphorus(V) sorption on sorbents based on aminopolystyrene and 4-amino-N-azobenzenesfulamide from aqueous solutions is studied. The following sorption parameters are determined: the optimum acidity, pH_opt; 50% sorption pH, pH₅₀; optimal time τ, min; quantitative-sorption temperature; and phosphorus(V) sorption capacity of the sorbent (SCS). Sorption isotherms are plotted.     

A physicochemical study of the sorption of lead: Correlations in a series of chelating polymer sorbents

The sorption properties of chelating polymer sorbents (CPSs), the derivatives of poly(styrene-2-oxy-azo-2′-oxybenzene), with respect to the lead ion are studied. The parameters of the sorption processes—optimum conditions of sorption (acidity, temperature, and time), the sorption capacities of sorbents, the possibility of desorption, and the stability constants of the chelated polymers—are determined. Quantitative correlations between p K′_OH of the functional analytical group (FAG) of the sorbent and σ _{o + p(p)} for ortho-and para-substituents, between p K′_OH and pH₅₀ for the formation of chelate complexes of lead, between p K′_OH and the stability of lead complexes (logβ), and between σ _{o + p(p)} and pH₅₀ for the formation of chelate complexes of lead are established with the aim of studying regularities of the influence of the structure and acid-base properties of FAGs on parameters of chemisorption of Pb²⁺. It is shown that the established correlations provide a means for quantitatively predicting physicochemical parameters of sorbents and the process of sorption of lead with the aim of targeted synthesis of CPSs and their use in the chemistry of polymer compounds and in the process of concentrating.     

Strontium(II) sorption by complexing polymeric sorbents with various structures

Optimal conditions for strontium(II) sorption by new complexing polymeric sorbents (CPSs) from aqueous solutions were studied, namely, optimal solution acidity (pH_opt), pH of 50% sorption (pH₅₀), and optimal time and temperature of quantitative sorption. The strontium(II) sorption capacities of the test sorbents (SCSs) were determined, and sorption isotherms were plotted. The strontium(II) sorption parameters determined were used to recognize the most efficient CPSs.     

New correlation between metal-hydrolysis p<Emphasis Type="Italic">K</Emphasis> and sorbent-ionization p<Emphasis Type="Italic">K</Emphasis> for prediction of the pH of 50% metal-cation sorption on a chelating polymer sorbent

Metal sorption on chelating polymer sorbents (CPSs) is studied. A correlation is found between the 50%-sorption pH and the metal-hydrolysis pK, and pH₅₀ is predicted.     

Beryllium(II) sorption from aqueous solutions by polystyrene-based chelating polymer sorbents

Optimal parameters of beryllium(II) sorption from aqueous solutions by polystyrene-based sorbents have been studied, namely: optimal sorption acidity (pH_opt), pH providing 50% sorption (pH₅₀), optimal time (τ, min) and temperature of quantitative sorption. The sorption capacities of the sorbents under study (SCSs) for beryllium(II) have also been determined; sorption isotherms have been constructed. The parameters determined for beryllium(II) sorption by chelating polymer sorbents (CPSs) make it possible to select the most efficient sorbent for practical use.     

Strontium(II) sorption by complexing o-hydroxy-azo-o’-hydroxy functionalized polystyrene polymer sorbents

Optimal parameters for strontium(II) complexing and sorption from aqueous solutions by sorbents based on styrene/divinylbenzene copolymers functionalized with a complexing o-hydroxy-azo-o-hydroxy functionality have been studied, namely, pH_opt, 50% sorption pH (pH₅₀), and the time and temperature of quantitative strontium(II) sorption. Strontium(II) sorption capacities have been determined for the sorbents under study; sorption isotherms have been constructed. For a complex formed with polystyrene-o-hydroxy-azo-o’-hydroxy-sulfobenzene, which is an efficient sorbent, the structure has been determined.     

Chelating tendencies in the rows of polymeric sorbents and their copper(II) and lead(II) complexes

The physicochemical properties of chelating polymer sorbents (CPSs), derivatives of poly(styrene-2-hydroxy-〈1-azo-1′〉-2′-hydroxybenzene), are studied with respect to copper and lead ions. The following sorption parameters are determined: the optimum acidity, temperature, and duration; the sorption capacity of the sorbent (SCS); and stability constants of polychelates. Quantitative correlations are found between the dissociation constants (pK′ _a) of the analytical functional group (AFG) of the sorbent, and the pH₅₀ of chelation of the tested metals; between p K′ _a and the stability of the complexes (logβ); and between pK′_a and the charge of the oxygen atom of the complexing group (z); these correlations are intended for use in elucidating the effect of the structural features and acid-base properties of the AFG on the chemisorption parameters of copper(II) and lead(II). These correlations predict the physical-chemical properties of sorbents and the sorption parameters of trace elements for preconcentrating and separating them from biological, natural, and technical objects     

Regularities of complexation in the series of sorbents on the polystyrene matrix and their complexes with chromium(III) and manganese(II)

The physicochemical properties of polymeric complexing sorbents with the o,o′-dihydroxy-(1-azo-1′)-functional complexing group were studied. Optimal sorption parameters for chromium(III) and manganese(II) (medium acidity, temperature, time), the sorption capacity of the sorbents, and the stability constants (pK _a′)of the complexes were determined. Correlation relations were established between the dissociation constants (pK _a′) of the sorbent functional group and pH₅₀ of the complexation of the considered elements; between and the stability of the formed complexes (logβ); and between pK _a′ and the deprotonation energy (E _depr) of the sorbent hydroxy group located in the para-position to the introduced substituent. The established correlation relations are useful for targeted prediction of the physicochemical parameters of the sorbents, their complexes, and the sorption of manganese(II) and chromium(III) aimed at recovery and pre-concentration of these ions from objects with various chemical composition.     

Formation of mixed-ligand complexes in the complexing polymer sorbent-Pb<Superscript>2+</Superscript>-dinitrophenol systems

The complexation of lead(II) with a group of synthesized sorbents based on aminopolystyrene and substituted phenols having structurally different substituents of various electronic natures in the para position with respect to phenolic hydroxyl was studied. As third components, α-dinitrophenol and γ-dinitrophenol were examined. The following most important parameters of sorption were determined: the optimum pH value of quantitative sorption (pH_opt), the recovery (R, %), the sorption capacity of the sorbent (SCS_Pb, mg/g), the half-sorption pH value (pH₅₀), and the temperature and time (τ) of sorption in the presence of a third component. The structure of the mixed-ligand complex was determined.     

Comparison of the sorption properties of crystalline and amorphous samarium(III) oxohydroxides

The influence of the pH of precipitation (pH₁) and the ionic medium on the sorption properties of as-precipitated samarium(III) oxohydroxides,i.e., the pH of zero charge point and the rate of heterogeneous hydrolysis of the IrCl₆ ²⁻, RhCl₆ ³⁻, and PtCl₄ ²⁻ complexes, was studied. The composition of precipitates was studied by the drop titration of solutions of samarium nitrate and thermography. It was found that as-predipitated samarium oxohydroxides are amorphous and the substitution of NO₃ ⁻ ions by OH⁻ is not complete even at pH₁ 11. Heterogeneous hydrolysis occurs on the surface of samarium oxohydroxide, and its rate increases with increasing pH₁. The as-precipitated samarium oxohydroxides have much higher sorption activities than crystalline Sm₂O₃, and their activities are similar to those of ferrogels. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 583–588, April, 1998.     

Separation and determination of some trivalent metal ions using rhodamine B grafted polyurethane foam

The incorporation of rhodamine B into polyurethane foam matrix was prepared by mixing the rhodamine B with polyol (polyether) prior to the addition of diisocyanate reagent to form the polyurethane foam material. Rhodamine B grafted polyurethane foam (Rod.B-PUF) was found to be very suitable for the separation and preconcentration of trivalent metal ions e.g. bismuth (III), antimony (III) and iron (III) from thiocyanate solutions. Bismuth and antimony were separated from concentrated acid medium (1–6 M H₂SO₄). Iron (III) was separated from pH 1 to 3. The kinetics of sorption of the Bi (III), Sb (III) and Fe (III) onto the Rod.B-PUF was found to be fast, the extraction is accomplished from 5 to 10 min with average values of half-life of sorption (t_1/2) of 2.9 min. The average values of the Gibbs free energy (ΔG) for the sorption of metal ions onto Rod.B-PUF are ?6.6 kJ mol^?1, which reflect the spontaneous nature of sorption process. The sorption mechanism of the metal ion onto Rod.B-PUF was also discussed.     

Komplexbildung und extraktion von kupfer und eisen sowie gallium mit isomeren langkettigen alkylchinolin-8-olenComplex formation and liquid-liquid extraction of copper,iron and gallium with isomeric long-chain alkylquinolin-8-ols

The extraction of copper(II) and iron(III) with the 5-nonyl-, 5- and 7-decyl- and 5-chloro-7-decyl derivatives of quinolin-8-ol was studied with chloroform, benzene or toluene as the organic solvent. Isomeric extractants show only small differences and are very suitable for the extraction of copper and its separation from iron, similarly to Kelex 100 (7-dodecenylquinolin-8-ol). With these derivatives log K_ex values are ?5.18 to ?6.08 for iron(III) with pH_0,5 = 4.5 to 5, whereas log K_ex values are 1.54 to 1.82 for copper(II) with pH_0,5 ≈ 1.35. The chelates of copper, iron and gallium with isomeric ligands, isolated as the solids, have characteristic differences in melting points and solubilities. To extract gallium from alkalin solution, only 7-alkyl-8-quinolinols proved as favourable.     

Synthesis,characterization of low density polyhydroxy polyurethane foam and its application for separation and determination of gold in water and ores samples

In this work, a new type of sorbent (low density polyhydroxy polyurethane Foam, LPPF) was synthesis by using water hydrolysis of polyurethanediazonium chloride salt. LPPF was characterized using different tools e.g. elemental analysis, UV–vis and IR spectra, TGA, SEM, density and pH_ZPC. It was tested for separation, preconcentration and determination of gold in environmental samples using batch and dynamic techniques. The sorption experimental data was fitted by the pseudo-first kinetic mathematical equation (R² = 0.991). The sorption rate of the Au (III) ions is very fast, the half-life (t_1/2) ≈ 34 s. The equilibrium process is well described by the Freundlich isotherm model, the R² value is 0.967, which attributed to the heterogeneous surface structure of the LPPF. The breakthrough capacity of LPPF and the recovery of gold ions were 0.36 mmol g⁻¹ (70.5 mg g⁻¹) and 99–100%, respectively. The lower detection limit of gold by using spectrophotometric method is 3.3 ng L⁻¹ with preconcentration factors ≈ 450 (RSD ∼ 1.66%, n = 4). The values of ΔG and ΔH for the sorption of gold onto LPPF were −12.5 and −103.5 kJ mol⁻¹, respectively, which indicate that the sorption of Au (III) onto LPPF is spontaneous and exothermic reaction. The obtained results indicate that the ion chelation and ion association might be the most probable mechanism of gold sorption onto LPPF. The study shows LPPF has the potential of application as an efficient sorbent for the extraction and determination of gold in water, gold alloys pharmaceutical and granite samples.     

Insights into sorption species of Eu(III) on γ-Al2O3 and bentonite under different pH: Studies at macro- and micro-scales

The sorption species of Eu(III) on γ-Al₂O₃ and bentonite was investigated by batch, surface complexation model (SCM), and X-ray absorption spectroscopy (XAS). The results showed that sorption edges of Eu(III) on γ-Al₂O₃ and bentonite were as expected shifted forward high pH with the increasing in Eu(III) concentration, and sorption of Eu(III) was strongly dependent on pH. In γ-Al₂O₃ system, sorption of Eu(III) was decreased above pH 8.5 at low concentration of Eu(III) because of water soluble carbonate species of Eu(III), however the decline did not appear at high concentration of Eu(III) possibly due to a offset effect of surface precipitation. Actually, the sorption species of Eu(III) on bentonite mainly referred to at least four kinds of species including ion exchange (>X₃Eu⁰) at low pH, inner-sphere complexes (>AlOEu²⁺ and >SiOEu²⁺) at neutral condition, and hydrolysis species (>SiOEu(OH) ₂ ⁰ ) at alkaline condition. Linear combination fitting (LCF) in k space testified that hydrolysis of Eu(OH)₃(s) and oxide of Eu₂O₃ species were major for Eu(III) sorption on γ-Al₂O₃, whereas Eu³⁺(aq) and hydrolysis species comprised sorption species on bentonite. Extended X-ray absorption fine structure (EXAFS) analysis further confirmed the prediction from SCM and LCF. In addition, the typical shells of Eu–Al in R range of 3.0–3.4 Å and Eu–Si at ~4.0 Å were found in radial structure functions, which was possibly identified to edge-shared bidentate of Eu(III) on Al₂O₃ and bentonite.     

The extraction of Yb(III) and Lu(III) with chloroform from aqueous solutions in the presence of cupferron

The equilibrium of distribution of Yb(III) and Lu(III) between chloroform and the aqueous phase in the presence of cupferron (the ammonium salt of N-nitrosophenylhydroxylamine) were studied as apH function of the aqueous phase and the concentration of N-nitrosophenylhydroxylamine (HL). The stability constants for theLnL _n ^3–n ) complexes (n=1÷3) being formed in the aqueous phase were established, as well as the equilibrium constants of the extraction reaction $$Ln(H_2 O)_m^{3 + } + 3HL_{(O)} \mathop \rightleftharpoons \limits^{K_{ex} } LnL_{3(O)} + 3H^ + + mH_2 O(Ln^{3 + } = Yb,Lu),$$ two-phase stability constants for theLnL ₃ complexes,pH _0.5 and the separation factor Lu(III) from Yb(III).     

Sorption of [Fe(CN)6]3− and [Fe(CN)6]4− ions on the surface of Fe(III), Cr(III), and Zr(IV) oxyhydroxide hydrogels from aqueous solutions

The sorption of [Fe(CN)₆]^3? and [Fe(CN)₆]^4? anions on the surface of Fe(III), Cr(III), and Zr(IV) oxyhydroxide hydrogels at various pH values of hydrogel precipitation from solutions without a support electrolyte and from NaCl and Na₂SO₄ solutions with an ionic strength of 0.5 was studied. It was found that isotherms of sorption of [Fe(CN)₆]^3? and [Fe(CN)₆]^4? anions from solutions without a support electrolyte and from NaCl solutions and those of sorption of [Fe(CN)₆]^4? from Na₂SO₄ solutions are described by the Langmuir equation. It was established that the sulfate background suppresses the sorption of [Fe(CN)₆]^3? on Fe(III) and Zr(IV) oxyhydroxides. Both anions are sorbed only when the surface of the oxyhydroxides is charged positively; the Langmuir equation parameters A _max and K tend to decrease to the point of zero charge as the pH value of oxyhydroxide precipitation increases. An electrostatic mechanism of the sorption of [Fe(CN)₆]^3? and [Fe(CN)₆]^4? anions was suggested.     

Gleichgewichte und Kinetik zur 1:1-Komplexbildung von Aluminium(III) mit Kojisäure in wäßriger Lösung

The reaction of aluminium(III) with kojic acid was investigated in the range ofpH=(1.6 ... 3.4) at excess of Aluminium(III). Only the complex AlL ²⁺ was formed with β₁₁=7.6. The results of equilibrium and kinetic measurements indicate that only the species Al³⁺, AlOH²⁺ and the neutral form of the ligand contribute to the reaction. Reaction values and rate constants are given. A general acid base catalysis was detected.     

Specific adsorption of cesium on silica-titania

The amphoteric nature of hydrous silica-titania gel and its sorption behaviour towards cesium were studied. In NaNO₃ solution, the point of zero change (pH_pzc) of the gel was found to be 4.22 by pH-titration. The fraction of protonated, deprotonated and neutral surface hydroxyl groups as a function of pH have been computed. Sorption of cesium increased with the increase of pH, reached maximum at a pH of 7 followed by a plateau. Significant uptake of cesium was observed even when the pH was less than pH_pzc. Nearly 70% sorption was observed at pH_pzc. The free energy of specific adsorption was found to be –18.7 kJ·mol^–1.     

Separation of Y from Sr by zirconium vanadate gel ion-exchanger sorbent: kinetics and thermodynamic study

A new zirconium vanadate (Zr–V) ion-exchanger was synthesized and characterized for fast and selective separation procedure of ⁹⁰Y from ⁸⁹Sr. The method was based on ⁹⁰Y(III) sorption from aqueous HCl solution containing ⁸⁹Sr(II) onto Zr–V gel exchanger. The kinetics of Y(III) sorption from HCl solution by Zr–V exchanger was subjected to Weber–Morris, Lagergren, Bhattacharya and Venkobachar, and Bt models. Initially, the uptake of Y(III) onto the exchanger was fast followed by kinetically first-order sorption with an overall rate constant, K _Lager = (3.55 ± 0.03) × 10^?4 min^?1. Film and intraparticle transport are the two steps that might influence Y(III) sorption. The negative values of ΔG of ⁹⁰Y retention dictate that, the process is a spontaneous. The negative values of ΔH and ΔS reflect the exothermic nature of ⁹⁰Y(IIsorption and the random uptake of ⁹⁰Y(III) onto Zr–V sorbent. Zr–V exchanger offers unique advantages of ⁹⁰Y(III) retention over conventional solid sorbents in rapid and effective separation of traces of ⁹⁰Y(III) from Sr. The exchanger was successfully packed in column for an effective separation of ⁹⁰Y.     

Sorption of Eu(III) on GMZ bentonite in the absence/presence of humic acid studied by batch and XAFS techniques

Bentonite has been extensively studied because of its strong sorption ability and low permeability. In this work, the Na-bentonite from Gaomiaozi County (China) has been characterized by XRD, FTIR and acid-base titration. The sorption of Eu(III) on Na-bentonite in the absence/presence of humic acid (HA) was studied at T = 25 ± 2 °C and in 0.01 mol/L NaClO₄ solution. The effects of pH, HA, contact time and initial Eu(III) concentrations were also investigated. The results indicate that the sorption of Eu(III) on Na-bentonite was dependent on pH values. The presence of HA had little effect on Eu(III) sorption at low pH values, but decreased Eu(III) sorption at high pH values. X-ray absorption fine structure spectroscopy (XAFS) was applied to characterize the local structural environment of the adsorbed Eu(III) on bare Na-bentonite and HA-bentonite hybrids. The results indicate that Eu(III) was bound to O atoms at a distance of about 2.39 Å at pH 4.15. The results are crucial for the evaluation of the sorption and migration of other trivalent lanthanides and actinides in bentonite as backfill materials.