The application of solid sorbents for the purification of aluminum contaminated chemicals used as modifiers in electrothermal atomic absorption spectrometry

Various microcolumns with solid sorbents (ion exchange resins, functionalised cellulose sorbents, chelating resins) have been tested with respect to their ability for the purification of aluminum contaminated chemicals used as modifiers in electrothermal atomic absorption spectrometry. The purification of NaNO(3), Mg(NO(3))(2), K(2)SO(4) and (NH(4))(2)HPO(4) has been the most effective with an almost 100% efficiency, when Spheron-Oxine was used as chelating resin. The sorption of aluminum from KOH solution has been found to be very high (around 90%) for all investigated sorbents. However, the best results have been obtained with anion-exchange resins. It has been difficult to purify concentrated mineral acids (HCl, H(2)SO(4)). A retention of aluminum above 80% has been achieved only when Cellex P, Chelex 100 or Amberlite XAD-2 have been used.     

New hybrid chelating sorbents with grafted 3-aminopropionate groups based on mixed silicon,aluminum, titanium,or zirconium oxides

A series of new hybrid organo-inorganic sorbents with the 3-aminopropionate chelating group was synthesized. The synthesis includes the copolycondensation (sol—gel method) of tetraethoxysilane, 3-aminopropyltriethoxysilane, and several modifiers (MeSi(OEt)₃, EtSi(OEt)₃, Ti(OEt)₄, AlONO₃, ZrOCl₂) followed by carboxyethylation with acrylic acid. The obtained chelating sorbents were characterized by elemental analysis, FT-IR and ¹H NMR spectroscopy, and thermogravimetry. The N-carboxylated sorbents have a higher sorption capacity with respect to metal ions (0.5–0.9 mmol g⁻¹, pH 6.3, NH₄OAc, 20 °C) than the starting sorbents with the primary amino group (0.05–0.2 mmol g⁻¹) and manifest high selectivity for copper(II) ion extraction. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1783–1788, August, 2005.     

Catalytic sulphation of limestone/lime with platinum

The effects of the presence of a Pt catalyst on the limestone/lime sulphation process were investigated by thermal analysis methods to provide a better understanding of the factors limiting gas desulphurization when Ca-based sorbents are used. It was found that for the Pt-catalysed sulphation of precalcined limestone the weight increase is above 100% higher under isothermal and dynamic conditions (up to 830°C). These results are direct evidence that Pt catalyses the CaO-SO₂-O₂ reaction. It can be presumed that the process proceeds through a gaseous intermediate, SO₃, a highly reactive gas, which explains the increased rate of sulphation. SO₃ then reacts with CaO to form CaSO₄ directly, in contrast with the non-catalysed oxidation of SO₂ to SO₃, where CaSO₃ formation is the most probable early stage of sulphation. The proposed mechanisms were supported by the phase identification of the products.     

Molten lithium sulphate-sodium sulphate—potassium sulphate eutectic. The reactions of six vanadium compounds

The solubilities and thermal stability of six vanadium compounds of oxidation states V, IV and III [i.e., V₂O₅, NaVO₄, Na₃VO₄, VOSO₄, VO₂ and KV(SO₄)₂] have been studied in the ternary eutectic (78 mole % Li₂SO₄, 8.5 mole % Na₂SO₄, 13.5 mole % K₂SO₄) and the products of their reactions with basic, acidic, oxidising and reducing reagents have been identified.     

Chelating resins for the concentration of trace elements from sea water and their analytical use in conjunction with atomic absorption spectrophotometry

An investigation has been made of the uptake of trace elements from both distilled water and sea water by the chelating ion-exchange resins Chelex-100 and Permutit S1005. The resins retained the following elements with an efficiency of ca. 100%: Ag, Bi, Cd, Cu, In, Pb, Mo, Ni, rare earths, Re (90% only), Sc, Th, W, V, Y and Zn. Manganese was retained quantitatively only by the Chelex resin. The following elements are removed with 100% efficiency by means of₂N mineral acids: Bi, Cd, Co, Cu, In, Ni, Pb, rare earths, Sc, Th, Y and Zn. Ammonia (4 N) completely removes molybdenum, tungsten, vanadium and rhenium. The resins have been used in conjunction with atomic absorption spectrophotometry for the simultaneous determination of zinc, cadmium, copper, nickel and cobalt in sea waters.     

Separation of titanium, iron and aluminium on a chelating resin with benzoylphenylhydroxylamine group and application to bauxite and clay

Summary A chelating polystyrene based resin containing N-benzoyl-N-phenylhydroxylamine has been sythesized by two methods and characterized. Conditions for quantitative separation of Ti(IV), Fe(III) and Al(III) on the resin have been studied. A method has been developed for the determination of these three metal ions in bauxite or clay samples after their separation on the resin with recoveries of 98.5–99.5% for different metal ions. The maximum sorption values are observed at pH 1, 2.5 and 2.5 for Ti(IV), Fe(III) and Al(III), respectively, which are recovered by successive elution with 1 mol/l H₂SO₄, 2 mol/l HCl and 4 mol/l H₂SO₄ in the above order.     

Phase ratios in the M<Subscript>2</Subscript>O-V<Subscript>2</Subscript>O<Subscript>5</Subscript>-SO<Subscript>3</Subscript> (M = Rb,Cs) systems and the properties of the compounds formed in these systems

Powder X-ray diffraction and microscopy have been used to study phase ratios of the M₂O-V₂O₅-SO₃ (M = Rb, Cs) systems, which model the active component of rubidium-vanadium and cesium-vanadium catalysts for sulfuric acid production at high sulfur dioxide conversions. We have stated that each system forms four compounds: M₃VO₂(SO₄)₂, MVO₂SO₄, M₄V₂O₃(SO₄)₄, and MVO(SO₄)₂. The thermal properties of these compounds and their interaction with water vapor saturated at room temperature have been studied. The unit cell parameters have been determined for the compounds MVO₂SO₄ (M = K, Rb), MVO(SO₄)₂, and M[VO₂(SO₄)(H₂O)₂] · H₂O (M = Rb, Tl). The reciprocal transformations of the components and phases of the M₂O-V₂O₅-SO₃ systems match the Lux-Flood ideas of the acid-base properties of oxide compounds.     

Preconcentration and atomic spectrometric determination of rare earth elements (REEs) in natural water samples by inductively coupled plasma atomic emission spectrometry

The usage of a variety of sorbents has been shown as promising matrix removal/preconcentration strategies for the determination of rare earth elements (REEs) in various natural water samples by inductively coupled plasma atomic emission spectrometry (ICP-AES). The sorption efficiency of various zeolites (clinoptilolite, mordenite, zeolite Y, zeolite Beta), ion-exchangers (Amberlite CG-120, Amberlite IR-120, Rexyn 101, Dowex 50W X18) and chelating resins (Muromac, Chelex 100, Amberlite IRC-718) towards REEs was investigated in terms of solution pH, shaking time and sorbent amount. The results have shown that most of the materials can take up REEs at a wide pH range. The experiments were continued with clinoptilolite, zeolite Y and Chelex 100 and it was demonstrated that all three materials displayed very fast kinetics for REE sorption (higher than 96% in 1 min). Desorption from the sorbents was realized with 2.0 M HNO₃ for clinoptilolite and 0.1 M HNO₃ for zeolite Y and Chelex 100. Only the lower concentration range (0.01-2.0 mg l⁻¹) of matrix-matched standards were used in quantitation although the calibration graphs were linear at least up to 10.0 mg l⁻¹ for all REEs studied. The limit of detection (3 s) without preconcentration was 0.1, 1.0, and 0.2 μg l⁻¹ for Eu, La, and Yb, respectively. The validity of the method with the selected sorbents was checked through spike recovery experiments.     

K<Subscript>3</Subscript>VO<Subscript>2</Subscript>(SO<Subscript>4</Subscript>)<Subscript>2</Subscript>: Formation conditions,crystal structure,and physicochemical properties

Potassium oxosulfatovanadate(V) K₃VO₂(SO₄)₂ has been obtained by solid-phase synthesis from K₂SO₄, K₂S₂O₇, and V₂O₅ (2: 1: 1), and its formation conditions, crystal structure, and physiochemical properties have been studied. The conversions of K₃VO₂(SO₄)₂ in contact with potassium vanadates and other potassium oxosulfatovanadates(V) are considered in terms of phase relations in the K₂O-V₂O₅-SO₃ system, which models the active component of vanadium catalysts for sulfur dioxide oxidation into sulfur trioxide. The X-ray diffraction pattern of K₃VO₂(SO₄)₂ is indexed in the monoclinic system (space group P2₁) with unit cell parameters of a = 10.0408(1) Å, b = 7.2312(1) Å, c = 7.3821(1) Å, β = 104.457(1)°, Z = 2, and V = 519.02 ų. The crystal structure of K₃VO₂(SO₄)₂ is built from [VO₂(SO₄)₂]^3? complex anions, in which the vanadium atom is in an octahedral oxygen environment formed by two terminal oxygen atoms (V-O(6) = 1.605(7) Å, V-O(10) = 1.619(7) Å and four oxygen atoms of the two chelating sulfate anions. The vibrational spectra of K₃VO₂(SO₄)₂ are analyzed using these structural data.     

Quinalizarin anchored on Amberlite XAD-2. A new matrix for solid-phase extraction of metal ions for flame atomic absorption spectrometric determination

Amberlite XAD-2 has been functionalized by coupling it to quinalizarin [1,2,5,8-tetrahydroxyanthraquinone] by means of an -N = N- spacer. Elemental analysis, thermogravimetric analysis, and infrared spectra were used to characterize the resulting new polymer matrix. The matrix has been used to preconcentrate Cu(II), Cd(II), Co(II), Pb(II), Zn(II), and Mn(II) before their determination by flame atomic absorption spectrometry (FAAS). UO₂(II) has been preconcentrated for fluorimetric determination. The optimum pH values for maximum adsorption of the metals are between 5.0 and 7.0. All these metal ions are desorbed (recovery 91–99%) with 4 mol L^–1 HNO₃. The adsorptive capacity of the resin was found to be in the range 0.94–5.28 mg metal g^–1 resin and loading half-life (t_1/2) between 5.3 and 15.0 min. The effects of NaF, NaCl, NaNO₃, Na₂SO₄, Na₃PO₄, Ca(II), and Mg(II) on the adsorption of these metal ions (0.2 μg mL^–1) are reported. The lower limits of detection for these metal ions are between 1 and 15.0 μg L^–1. After enrichment on this matrix flame AAS has been used to determine these metal ions (except the uranyl ion) in river water samples (RSD ≤ 6.5%); fluorimetry was used to determine uranyl ion in well water samples (RSD ≤ 6.3%). Cobalt from pharmaceutical vitamin tablets was preconcentrated by use of this chelating resin and estimated by FAAS (RSD ～ 4%).     

Investigation of double sulfates of lithium and rare earth elements

Compounds in the system Li₂SO₄R₂(SO₄)₃, where R is a rare earth element, have been investigated. Only compounds of the type LiR(SO₄)₂ are formed. The existence of three structural types has been established. X-Ray parameters from Nd to Er have been determined. The thermal stability of the compounds has been investigated.     

Reversible SO2 Uptake by Tetraalkylammonium Halides: Energetics and Structural Aspects of Adduct Formation Between SO2 and Halide Ions

Contact with SO₂ causes almost immediate dissolution of tetraalkylammonium halides, R₄NX, (R = CH₃ (Me), X = I; R = C₂H₅ (Et), X = Cl, Br, I; R = C₄H₉ (nBu), X = Cl, Br), with the formation of an adduct, [R₄N]⁺[(SO₂)_nX]^– (n = 1–4). Vapor pressure measurements indicate the proclivity for SO₂ uptake follows the order N(CH₃)₄⁺ < N(C₂H₅)₄⁺ < N(C₄H₉)₄⁺. This trend is in accord with the Jenkins–Passmore volume‐based thermodynamic model. Born–Haber cycles, incorporating the lattice energy and gas phase energy terms, are used to evaluate the energetic feasibility of reactions. Density functional theory calculations (B3PW91; 6‐311+G(3df)) have been used to calculate the energetics of (SO₂)_nX^– (X = Cl and Br) anions in the gas phase. The experimental studies show that tetraalkylammonium halides are feasible sorbents for SO₂. In order to correlate the theoretical model, experimental enthalpy, Δ_rH° and entropy, Δ_rS° changes have been determined by the van't Hoff method for the binding of one SO₂ molecule to (C₂H₅)₄NCl, resulting in the liquid adduct (C₂H₅)₄NCl · SO₂. The structure of the analogous 1:1 bromide adduct, (C₂H₅)₄NBr · SO₂, has been determined by single‐crystal X‐ray diffraction (monoclinic, P2₁/c, a = 9.1409(14) Å, b = 12.3790(19) Å, c = 11.3851(17) Å, β = 107.952(2)°, V = 1225.6(3) ų). The structure consists of discrete alkylammonium cations, bromide anions and SO₂ molecules with short contacts between the anion and SO₂ molecules. The (C₂H₅)₄N⁺ cationadopts a transoid conformation with D_2d symmetry, and represents a rare example of a well‐ordered (C₂H₅)₄N⁺ cation in a crystal structure. The Br^– anions and SO₂ molecules forms a chain, (SO₂Br^–)_n, with bifurcated contacts. Non‐bonding electron pairs on the halide anions engage in electrostatic interactions with the sulfur atoms and charge‐transfer interactions with the antibonding S–O orbitals of the bound SO₂ moiety. Raman and ¹⁷O NMR spectra provide compelling evidence for a charge‐transfer interaction between SO₂ molecules and the halide ions.     

Application of countercurrent chromatography to the purification of chemical reagents

Countercurrent chromatography has been employed for the purification of solid chemical reagents, such as (NH₄)₂SO₄, NH₄HSO₄, NH₄F and NH₄Cl from a number of most common metal impurities (Fe, Al, Zn, Cu, Co, Cd, Ni, Cr, Ca, Mg, K) in order to gain high-purity reagents. After evaporation these can be used for fusion decomposition purposes in trace analysis of various refractory materials (e.g. high tech ceramics). N,N-hexamethylenedithiocarbamic acid, 8-hydroxyquinoline, dibenzo-18-crown-6 and dicyclohexano-18-crown-6 were used as extracting reagents.     

The contraction of granules of nanoporous super-cross-linked polystyrene sorbents as a result of the exclusion of large-sized mineral electrolyte ions from the polymer phase

The deformation of neutral super-cross-linked polystyrene sorbents and ionites based on styrene-divinylbenzene gel-type copolymers brought in contact with concentrated solutions of HCl, H₃PO₄, NaOH, NH₄Cl, (NH₄)₂SO₄, and LiCl electrolytes was studied by dilatometry for separate spherical granules. Considerable contraction of super-cross-linked polystyrene matrices swollen in water was observed in concentrated solutions containing large-sized lithium, sulfate, and phosphate ions. Volume compressive strain correlated with the size of excluded hydrated ions. The contraction effect was caused by the difference in the osmotic pressure of water in thin pores and water in concentrated solutions filling large pores. The exclusion effect ignored earlier should also influence the degree of ion exchange and volume deformation of standard ion-exchange resins brought in contact with solutions of various electrolytes. Original Russian Text ? A.V. Pastukhov, V.A. Davankov, M.P. Tsyurupa, Z.K. Blinnikova, N.E. Kavalerskaya, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 3, pp. 541–549.     

Coagulation of the Suspended Organic Colloids Using the Electroflocculation Technique

Electroflotation is an unconventional separation process owing its name to the bubbles generation method (i.e., electrolysis of the aqueous medium) caused by the hydrogen and hydroxide development. Collecting the colloidal particles in surface water has been a long-term issue all over the world, because of their adverse influence. In the present research, the electroflocculation technique have been use to collect the humus particles throughout the polluted wastewater. The uses of different chemical additives namely, Al₂(SO₄)₃, Al(OH)₃, CaCl₂, CaO, and Na₂SiO₃ were also successfully examined and enhanced the electroflocculation technique. Although high negatively surface electrical charge of humus causes difficulties in the conventional flocculation and coagulation technique, it enhances the flocculation process when the electroflocculation techniques have been used. The results of both Jar test and electroflocculation technique are further compared. It can be concluded that the polluted water were fully decontaminated (i.e., all of the suspended colloids through the water were removed) by using the electroflocculation technique. The removal rate after electroflocculation test were 91.8%, 98%, 93.5%, 85.3%, 95.4%, and 94% for neutral, Al₂(SO₄)₃, Al(OH)₃, CaCl₂, CaO, and Na₂SiO₃, respectively. While the removal rate after Jar test were 84.8%, 83.79%, 71.44%, 84.83%, 77.09%, and 77.09% for neutral, Al₂(SO₄)₃, Al(OH)₃, CaCl₂, CaO, and Na₂SiO₃, respectively.     

Sorption characteristics of chelating resins

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.     

Preparation and characterization of double metal-silica sorbent for gas filtration

This paper presents the preparation of a porous (Mg, Ca) silicate structure, which could be employed as sorbent filter media. The sorbents have been prepared using sodium silicate precipitated with various ratios of magnesium and calcium salts. The sorbents obtained were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD) and nitrogen physisorption isotherm. Further, the applicability and performance of the sorbent impregnate with potassium hydroxide for removal of sulphur dioxide (SO₂) has been demonstrated. From the isotherms, specific surface area, pore diameter and volume of pores were estimated. Results show that the chemical composition and textural properties of the resultant sorbents were highly dependent on Mg/Ca molar ratio. It was found that sorbents made with 68 mol% Mg and 32 mol% Ca (PSS-MgCa-68/32); and 75 mol% Mg and 25 mol% Ca (PSS-MgCa-75/25) exhibited even higher specific surface area and pore volume than the sorbents containing a single metal. The Mg/Ca-silica sorbents obtained contains interconnected bimodal porosity with large portions being mesopores of varied sizes. The pore size distribution (PSD) results further indicate that PSS-MgCa-68/32 sorbent exhibits wide PSD of interconnected pores in the size range of 1 to 32 nm while PSS-MgCa-50/50 and PSS-MgCa-75/25 exhibits narrow PSD of 1 to 5 nm. Using SO₂ as model contaminate gas, it was shown that the dynamic adsorption performance of the PSS-MgCa-sorbents impregnated with 8 wt% KOH exhibits SO₂ uptake, with impregnated PSS-MgCa-68/32 showing better performance. This shows that the materials prepared can be used as adsorbent for gas filtration.     

Electronic absorption spectra of MnO4− ions in single crystals of alums

The electronic absorption spectra of MnO₄^? ions in the single crystals of KA1(SO₄)₂·12H₂O and NH₄A1(SO₄)₂·12H₂O at room temperature and liquid nitrogen temperature are reported. The assignments of the absorption bands observed at around 5200 Å, 3600 Å, 3000 Å and 2300 Å have been made in a consistent manner. The molecular orbital energy level scheme given by Johnson and Smith on the basis of a spin-unrestricted SCF Xα cluster model has been used in conjunction with Slater's transition state theory to interpret the optical absorption spectra.     

螯合树脂研究 Ⅻ.以聚硫醚为主链的异丙巯基胺树脂的合成及其吸附性能

 由聚环硫氟丙烷与多乙烯多胺反应制得的聚合物(PB)再与环硫丙烷反应,合成了四种以聚硫醚为主链的异丙巯基胺树脂(PBM_1-4)。树脂对Au³⁺、Pd²⁺、Pt⁴⁺、Ag⁺和Hg²⁺等离子具有强的吸附能力,对Cu²⁺次之,对Zn²⁺和Pb²⁺很弱。树脂对贵金属具有高的选择性,能从含Au³⁺、Cr³⁺、Co²⁺、Ni²⁺、Cu²⁺、Mn²⁺、Zn²⁺和Fe³⁺的溶液中定量吸附Au³⁺而不吸附其它离子。     

Solid-state reactions between alkali persulfates and oxides of corundum structure

The effects of three corundum structure oxides, α-Al₂O₃, α-Cr₂O₃, and α-Fe₂O₃, on the thermal decomposition of sodium and potassium peroxodisulfates (persulfates) under non-isothermal static air conditions and using various oxide/persulfate molar ratios, have been thermoanalytically investigated. Compounds such as Na₃Al(SO₄)₃, K₃Al(SO₄)₃, Cr₂(SO₄)₃, K₃Cr(SO₄₃, and Na₃Fe(SO₄)₃ are identified by X-ray diffractometry and conventional chemical analysis. The molar ratios as well as temperatures of the stoichiometric formation for these compounds have been established. At higher temperatures, α-Al₂O₃ acts as a promoter catalyst for the decomposition of pyrosulfate to sulfate, whereas α-Cr₂O₃ behaves as a retarder for the decomposition of persulfate. A eutectic mixture is formed between K₃Al(SO₄) and K₂SO₄ at 675°C. Also, K₃Fe(SO₄)₃ is identified as two crystalline phases.