SEPARATION OF PALLADIUM(II) FROM PLATINUM(II), IRIDIUM(III), AND RHODIUM(III) USING CENTRIFUGAL PARTITION CHROMATOGRAPHY

The separation of Pd(II) from Pt(II), Ir(III) and Rh(III) with trioctylphosphine oxide (TOPO) in heptane using centrifugal partition chromatography (CPC) has been investigated for the first time. The extraction of Pd(II) has been studied by CPC and batch solvent extraction. The distribution ratios for Pd(II) determined by both methods agree well. In low HCl concentrations (<0.1 M), the extracted species was PdCl₂.(TOPO)₂, irrespective of the chloride concentration, while at acid concentrations above 0.1 M, the Pd was extracted as the ion pair, 2(TOPO.H⁺).PdCl₄ ^2-. Base line separation of Pd(II) and Pt(II) in CPC was obtained under a variety of chloride and HCl concentration with the average number of theoretical plates being 390 ± 40 at a flow rate of 0.47 ± 0.05 mL/min.     

Separation of Mercury(II) as Chloride from Zinc(II), Cadmium(II), Gold(III), and Thallium(III) by Extraction in High-Molecular-Weight Amines

Abstract

The extraction behavior of Zn(II), Cd(II), Hg(II), Au(III), and Tl(III) has been studied at different HCl molarities in some commercially available liquid anion exchangers. The effect of such variables as the type of amine, molarity of HCl, amine concentration, and organic diluent on extraction has been explored to suggest the best conditions of separation of Hg(II) from Zn(II), Cd(II), Au(III), and Tl(III).     

Adsorption of Cr(III), Ni(II), Zn(II), Co(II) ions onto phenolated wood resin

In this study, phenolated wood resin was used an adsorbent for the removal of Cr(III), Ni(II), Zn(II), Co(II) ions by adsorption from aqueous solution. The adsorption of metal ions from solution was carried at different contact times, concentrations and pHs at room temperature (25°C). For individual metal ion, the amount of metal ions adsorbed per unit weight of phenolated wood resin at equilibrium time increased with increasing concentration and pH. Also, when the amounts of metal ions adsorbed are compared to each other, it was seen that this increase was order of Cr(III) > Ni(II) > Zn(II) > Co(II). This increase was order of Cr(III) > Ni(II) > Co(II) > Zn(II) for commercial phenol–formaldehyde resin. Kinetic studies showed that the adsorption process obeyed the intraparticle diffusion model. It was also determined that adsorption isotherm followed Langmuir and Freundlich models. Adsorption isotherm obtained for commercial phenol–formaldehyde resin was consistent with Freundlich model well. Adsorption capacities from Langmuir isotherm for commercial phenol–formaldehyde resin were higher than those of phenolated wood resin, in the case of individual metal ions. Original adsorption isotherm demonstrated the monolayer coverage of the surface of phenolated wood resin. Adsorption kinetic followed the intraparticle diffusion model. The positive values of ΔG° determined using the equilibrium constants showed that the adsorption was not of spontaneous nature. It was seen that values of distribution coefficient (K_D) decreasing with metal ion concentration in solution at equilibrium (C_e) indicated that the occupation of active surface sites of adsorbent increased with metal ions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2838–2846, 2006     

Synthesis and characterization of antibacterial polychelates of urea–formaldehyde resin with Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) metal ions

We studied the reaction between urea and formaldehyde with the purpose of preparing new polychelates of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) metal ions. These compounds were characterized by elemental analysis, IR spectroscopy, ¹H‐NMR, electronic spectroscopy, thermogravimetric analysis (TGA), and molar conductance measurements. The percentage of metal in all of the polychelates was found to be consistent with 1:1.5 (metal/ligand) stoichiometry. The thermal behaviors of these coordination polymers were studied by TGA in a nitrogen atmosphere up to 750°C. The TGA results reveal that the complexes had higher thermal‐resistance properties compared to the common urea–formaldehyde resin. The molar conductivity and magnetic susceptibility measurements of the synthesized polychelates confirmed the geometry of the complexes. The antibacterial activity of the polychelates was also investigated with agar diffusion methods. The antibacterial activity of these polychelates was found to be reasonably good compared with standard drugs, namely, ciprofloxacin, ampicillin, and kanamycin. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 928–936, 2006     

Separation and concentration processes of solutions of Co(II), Ni(II), Cr(III), Fe(III) and Mn(II) by extraction with toluene-dissolved rosin

The extraction and stripping of Co(II), Ni(II), Cr(III) and Fe(III) from aqueous solutions by rosin dissolved in toluene has been investigated. Results obtained show that rosin is better extractant than abietic or n-lauric acids under comparable conditions. From these results, and the data of Mn(II) solvent extraction studied previously under the same conditions, a separation and concentration process for these five cations in aqueous solutions has been designed. Saturated solutions of Fe(III), Cr(III), Mn(II) and finally Co(II) and Ni(II) have been obtained successively by extraction and stripping, by addition of ammonium hydroxide to obtain the appropriate pH value, and by modifying adequately the organic phase/aqueous phase volume ratio.     

Extraction Behavior of Zinc(II), Cadmium(II), Mercury(II), Indium(III), and Thallium(III) as Thiocyanates in High-Molecular-Weight Amines and Some Mutual Binary Separations

Abstract

The extraction behavior of Zn(II), Cd(II), Hg(II), In(III), and Tl(III) has been studied at different NH₄CNS molarities in some commercially available liquid anion exchangers. The effect of such variables as the type of amine, molarity of NH₄CNS, and pH of aqueous phase and organic diluent on extraction has been explored to achieve the best conditions of some mutual binary separations of analytical and radiochemical interest.     

Evaluation of sorption behavior of polymethylene-bis(2-hydroxybenzaldehyde) for Cu(II), Ni(II), Fe(III), Co(II) and Cd(II) ions

Poly[5,5??-methylene-bis(2-hydroxybenzaldehyde)1,2-phenylenediimine] resin was prepared and characterized by employing elemental, thermal analysis, FTIR, and UV?Cvisible spectroscopy. The metal uptake behavior of synthesized polymer towards Cu(II), Co(II), Ni(II), Fe(III) and Cd(II) ions was investigated and optimized with respect to pH, shaking speed, and equilibration time. The sorption data of all these metal ions followed Langmuir, Freundlich, and Dubinin?CRadushkevich isotherms. The Freundlich parameters were computed 1/n?=?0.31?±?0.02, 0.3091?±?0.02, 0.3201?±?0.05, 0.368?±?0.04, and 0.23?±?0.01, A?=?3.4?±?0.03, 4.31?±?0.02, 4.683?±?0.01, 5.43?±?0.03, and 2.8?±?0.05?mmol?g^?1 for Cu(II), Co(II), Ni(II), Fe(III), and Cd(II) ions, respectively. The variation of sorption with temperature gives thermodynamic quantity (??H) in the range of 36.72?C53.21?kJ/mol. Using kinetic equations (Morris?CWeber and Lagergren equations), values of intraparticle transport and the first-order rate constant was computed for all the five metals ions. The sorption procedure is utilized to preconcentrate these ions prior to their determination by atomic absorption spectrometer. It was found that the adsorption capacity values for metal-ion intake followed the following order: Cd(II)?>?Co(II)?>?Fe(III)?>?Ni(II)?>?Cu(II).     

Water-soluble oxidized starch in complexation of Fe(III), Cu(II), Ni(II) and Zn(II) ions

The structure of the bromate-oxidized wheat starch (OS) contains partly opened glucose units with carbonyl and carboxyl groups at C2-, C3- or C6-positions. OS with a variable degree of oxidation (DO) was studied in alkaline conditions as a water-soluble complexing agent for Fe(III), Cu(II), Ni(II) and Zn(II) ions, which are common in various wastewaters. Complexation was studied by inductively coupled plasma-optical emission spectrometry (ICP–OES) in a single metal ion or multi-metal ion solutions. The DO affected the efficiency of the complexation with metal ions. OS with the high DO (carboxyl and carbonyl DO of 0.72 and 0.23, respectively) complexed and held Fe(III) or Zn(II) ions in a soluble form effectively in 0.5 mM single ion alkaline solution with the molar ratio of 0.65:1 of oxidized starch-to-metal ion (OS-to-M). The OS-to-M molar ratio of 1.3:1 was required to form a soluble complex with Cu(II) or Ni(II) ions. These complexes were thermally stable at the temperature range of 20–60 °C. OS with the low DO (carboxyl and carbonyl DO 0.47 and 0.17, respectively) complexed Zn(II) ions highly, Cu(II) and Ni(II) ions poorly and Fe(III) ions only partly. In the multi-metal ion solution of OS the solubility of these metal ions improved with the increasing DO of starch, which followed the same tendency as was observed in the single metal ion systems. The increased molar ratio of OS-to-M improved the complexation and solubility of the metal ions in all multi-metal ion series. As the soluble multi-metal ion complexes were reanalyzed after 7 days, all solutions had kept the high complexation and solubility of metal ions (ca. 90%). Complexation by OS did not show a selective binding of the ions in the multi-metal ion solution. It was concluded that the flexible, opened ring structure units of OS prevented the selective binding to metal ions but made the complexes highly stable. Titrimetric studies of OS–Fe(III) complexation showed that each anhydroglucose unit of OS had more than one coordination site and as the content of OS increased, the free sites coordinated to Fe(III) ions and formed cross-linked starch structures.     

Adsorption of As(III), As(V), Cd(II), Cu(II), and Pb(II) from Aqueous Solutions by Natural Muscovite

Various parameters were tested for the application of natural muscovite (NM) in the removal of metals from aqueous solutions: contact time, pH, ionic strength, and initial metal concentrations. Kinetic studies showed that the pseudo-second-order model explains well the sorption process. The adsorption of metals was greatly influenced by solution pH but not by ionic strength. The results from isotherm studies agreed more with the Freundlich isotherm model than with the Langmuir isotherm model. The adsorbed quantity of metals by NM was lower than that by the purified mica. These results suggested that the composition and surface characteristics of natural minerals may seriously influence applications for water purification.     

Solvent Extraction Separation of Chromium(VI), Iron(III), Cobalt(II), and Nickel(II) with Di-n-pentyl Sulfoxide

Abstract

Di-n-pentyl sulfoxide (DPSO) was employed for the solvent extraction separation of some transition metals from hydrochloric acid medium. It was found that chromium(VI) gets extracted at low acid concentrations (3 to 4.5 M), and iron(III) and cobalt(II) only above 5 M HCl. Nickel was not extracted at any of the test conditions. These transition metals were separated from one another by suitable choice of the extraction conditions.     

A new method for the simultaneous determination of Fe(III), Cu(II), Pb(II), Zn(II), Cd(II), and Ni(II) in wine using differential pulse polarography

A new and simple differential pulse polarographic method for the analysis of wine has been established. With this method, it was possible to determine simultaneously six trace elements in wine. There was no need for time consuming extraction and separation procedures with danger of contamination. The polarogram of wet digested wine was taken initially in pH 2 acetate buffer and Pb, Cd, and Zn were determined by standard additions. Ethylene diamine tetraacetic acid (EDTA) was added and pH was increased to six by addition of NaOH. Fe and Cu were determined subsequently. The ammonia buffer, pH 9.5, was identified as the best medium for separation and determination of Ni and Zn. The quantities of trace elements were found as Cu 290 ± 20 μg L⁻¹, Fe 8960 ± 50 μg L⁻¹, Pb 148 ± 17 μg L⁻¹, Cd 16 ± 8 μg L⁻¹, Zn 460 ± 25 μg L⁻¹, and Ni 78 ± 17 μg L⁻¹.     

Selective separation and concentration of Pd(II) from Fe(III), Co(II), Ni(II), and Cu(II) ions using thiourea‐formaldehyde resin

Thiourea‐formaldehyde (TUF), a well‐known chelating resin, has been synthesized and it was used in the adsorption, selective separation, and concentration of Pd(II) ions from Fe(III), Co(II) Ni(II), and Cu(II) base metal ions. The composition of the synthesized resin was determined by elemental analysis. The effect of initial acidity/pH and the adsorption capacity for Pd(II) ions were studied by batch technique. The adsorption and separation of Pd(II) were then examined by column technique. FTIR spectra and SEM/EDS analysis were also recorded before and after the adsorption of Pd(II). The optimum pH was found to be 4 for the adsorption. The adsorption data fitted well to the Langmuir isotherm. The maximum adsorption capacity of the TUF resin for Pd(II) ions was found to be 31.85 mg g⁻¹ (0.300 mmol g⁻¹). Chelating mechanism was effective in the adsorption. Pd(II) ions could be separated efficiently from Fe(III), Cu(II), Ni(II), and Co(II) ions using TUF resin. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Fluorescence-Responsive Detection of Ag(I), Al(III), and Cr(III) Ions Using Cd(II) Based Pillared-Layer Frameworks

Two Cd(II) based coordination polymers, {Cd₃(btc)₂(BTD-bpy)₂]∙1.5MeOH∙4H₂O}_n (1) and [Cd₂(1,4-ndc)₂(BTD-bpy)₂]_n (2), where BTD-bpy = bis(pyridin-4-yl)benzothiadiazole, btc = benzene-1,3,5-tricarboxylate, and 1,4-ndc = naphthalene-1,4-dicarboxylate, were hydro(solvo)thermally synthesized. Compound 1 has a three-dimensional non-interpenetrating pillared-bilayer open framework with sufficient free voids of 25.1%, which is simplified to show a topological (4,6,8)-connected net with the point symbol of (3²4²56)(3⁴4⁴5⁴6²8)(3⁴4²6¹⁹7²8). Compound 2 has a three-dimensional two-fold interpenetrating bipillared-layer condense framework regarded as a 6-connected primitive cubic (pcu) net topology. Compounds 1 and 2 both exhibited good water stability and high thermal stability approaching 350 °C. Upon excitation, compounds 1 and 2 both emitted blue light fluorescence at 471 and 479 nm, respectively, in solid state and at 457 and 446 nm, respectively, in the suspension phase of H₂O. Moreover, compounds 1 and 2 in the suspension phase of H₂O both exhibited a fluorescence quenching effect in sensing Ag⁺, attributed to framework collapse, and a fluorescence enhancement response in sensing Al³⁺ and Cr³⁺, ascribed to weak ion–framework interactions, with high selectivity and sensitivity and low detection limit.     

Recovery and Separation of Lanthanum(III), Aluminum(III), Cobalt(II), and Nickel(II) from Misch Metal by Solvent Extraction Using Bis(2-ethylhexyl) phosphinic Acid

Abstract

This paper describes use of bis(2-ethylhexyl) phosphinic acid as a reagent for extraction and mutual separation of lanthanum(III), aluminum(II), cobalt(II), and nickel(II) in 1.0 mol/L sodium nitrate. The extraction and stripping behavior of the four metal ions has been investigated using the extractant in Solvesso #150 as a diluent. The mutual separation and recovery of the metal ions from their mixtures has been tested by multistage extraction with a conventional separator funnel. A set of separation schemes has also been proposed for a continuous countercurrent multistage extraction which is comprised of ten extraction stages, four scrubbing stages, and seven stripping stages. Lanthanum(III) and aluminum(III) are coextracted but separated by selective stripping into different concentrations of hydrochloric acid. Cobalt(II) can be extracted with the nickel(II)-preloaded extractant solution, whereas nickel(II) remains in the aqueous phase. The successful separation of these metal ions from a misch metal-simulated sample is presented.     

LIQUID-LIQUID EXTRACTION OF GOLD(III) AND ITS SEPARATION OVER COPPER(II), IRON(III), AND ZINC(II) USING THIOUREA DERIVATIVES FROM CHLORIDE MEDIA

ABSTRACT

Selective liquid-liquid extraction of Au(III) from aqueous chloride media (1 mol/L NaCl) into cumene by thiourea derivatives namely 2a-c (N-thiocarbamoylbenzamidine derivatives), 3a-f (N-benzoylthiourea derivatives) has been investigated in detail. Marked differences in the metal extraction are noted using these organic compounds with respect to their structural variation. The extraction behaviour of Au(III) with extractants 2a-c and 3a-f followed the order : 2b> 2a>2c and 3e≈ 3c≈ 3d >3a >3f≈3b, respectively. The organic reagent 2a and 3c were selected for further detailed studies owing to their better strippability behaviour. Optimum conditions such as structure of the organic extractant, aqueous phase pH, diluent, time of equilibration, metal concentration, extractant concentration, effect of other metal cations were established for extraction separation of Au(III). Experimental data have been treated graphically and numerically by means of the computer programme LETAGROP-DISTR, and can be explained by assuming the formation of the species AuCl₃L and AuCl₃L₂ for 2a-c and AuCl₃L₂ for 3a-f derivatives. The lack of interference from even appreciable amounts of possible base metals such as Cu(II), Zn(II) and Fe(III) may be considered an outstanding advantage of the method for separation of gold from these metals using 2a and 3c.     

Piperazine Functionalized Resins for Au(III), Pt(IV), and Pd(II) Sorption

The result of synthesis of anion exchangers bearing piperazine functionalities is presented in this paper. A series of new ion exchange resins was synthesized by modification of VBC/DVB copolymer with 1(2-aminoethyl)piperazine (resin 1P), 1-amino-4-methylpiperazine (resin 2P), and 1-methylpiperazine (resin 3P). Adsorption studies of gold, platinum, and palladium were conducted with batch and dynamic method from multicomponent solutions containing AuCl₄^?, PtCl₆^2?, and PdCl₄^2? in the concentration range 10 mg/dm³ to 919 mg/dm³. The resins revealed excellent sorption ability towards these metals. The greatest total sorption capacities were determined as 331 mg/g Au for 2P resin, 405 mg/g Pt for 3P resin, and 150 mg/g Pd for 1P resin. The examined 3P resin showed the best total sorption capacity 796 mg/g. Affinity studies were also conducted. The examined resin 1P revealed the greatest affinity to platinum and palladium (lgK 4.5-5) whereas resin 2P revealed the best affinity to gold where lgK were ca. 4.9.     

Synthesis and properties of chelate polymers of VO(II), Mn(II), Zn(II), Fe(III), and Cr(III) with schiff base of 5,5′-methylene bis-salicylaldehyde with aniline

Polychelates of VO(II), Mn(II), Zn(II), Fe(III), and Cr(III) were prepared from Schiff base of 5,5′-methylene bis-salicyladehyde with aniline. All the chelate polymers are amorphous and insoluble in common organic solvents. They have very little solubility in DMF. The first three polychelates are found to be noncharged chelate polymers while the last two polychelates are found to be ionic from their conductivities in DMF. Their probable structures were determined from reflectance electronic spectral and magnetic measurements in conjunction with infrared measurements. The thermal stability, order of reaction and activation energy for all the polychelates were determined from their thermogravimetric analyses.     

Removal of Cu(II), Fe(III), and Cr(III) from Aqueous Solution by Aniline Grafted Silica Gel

Abstract

The aniline moiety was covalently grafted onto silica gel surface. The modified silica gel with aniline groups (SiAn) was used for removal of Cu(II), Fe(III), and Cr(III) ions from aqueous solution and industrial effluents using a batch adsorption procedure. The maximum adsorption of the transition metal ions took place at pH 4.5. The adsorption kinetics for all the adsorbates fitted better the pseudo second‐order kinetic model, obtaining the following adsorption rate constants (k₂): 1.233 · 10^?2, 1.902 · 10^?2, and 8.320 · 10^?3 g · mg^?1 min^?1 for Cr(III), Cu(II), and Fe(III), respectively. The adsorption of these transition metal ions were fitted to Langmuir, Freundlich, Sips, and Redlich‐Peterson isotherm models; however, the best isotherm model fitting which presented a lower difference of the q (amount adsorbed per gram of adsorbent) calculated by the model from the experimentally measured, was achieved by using the Sips model for all adsorbates chosen. The SiAn adsorbent was also employed for the removal of the transition metal ions Cr(III) (95%), Cu(II) (95%), and Fe(III) (94%) from industrial effluents, using the batch adsorption procedure.