Sorption and preconcentration of copper and cadmium on silica gel modified with 3-aminopropyltriethoxysilane

3-Aminopropyltriethoxysilane, (C₂H₅O)₃ Si(CH₂)₃NH₂, loaded on silica gel was used as a pre-concentration sorbent for copper and cadmium prior to their determination by flame atomic absorption spectrometry (FAAS). Both batch and column methods were used for the separation of the above metals. The analytes are quantitatively retained on the proposed adsorbent at pH 6.5. The complexation capacity of the collector is 0.032 mmol Cu/g silica. In the batch method, the effects of shaking time and the ratio of metal/silica on the retention by the asorbent were investigated. Columns filled with the collector provided quantitative recovery of the above metals from standardized samples as well as from sodium chloride solutions.     

Preconcentration of silver(I), gold(III) and palladium(II) in sea water with p-dimethylaminobenzylidenerhodanine supported on silica gel

A water-insoluble chelating material, p-dimethylaminobenzylidenerhodanine on silica gel (DMABR—SG) is described for preconcentration of trace amounts of silver(I), gold(III) and palladium(II) from water samples. Radioactive tracers (^110mAg and ¹⁹⁵Au) were used to study the behavior of silver and gold; palladium was monitored spectrophotometrically as its 1-(2-pyridylazo)naphthol complex in chloroform. In batch experiments, silver was quantitatively retained on the DMABR—SG at acidities ranging from 1.7 M to pH 5, and gold from 3 M to pH 5; equilibrium was achieved within 1 min for both elements. From sea water, silver ion was completely retained at pH 1.0–6.5 and gold ion at pH 1.0–3.5. In the case of palladium, shaking for about 20 min was required for quantitative retention at pH 1.0–5.0 for aqueous solution and at pH 1.0–7.0 for sea water. The chelating capacity of the DMABR—SG was 23 μmol Ag, 11 μmol Au and 11 μmol Pd per g. Quantitative recovery of silver and gold on DMABR—SG columns from sea water was achieved at higher flow rates (1–2 l h^-1 and 2–3 l h^-1, respectively) than with other chelating resins, e.g., Chelex 100, palladium required slower flow rate (150 ml h^-1). Silver retained on the DMABR—SG column was completely eluted with 20 ml of 2.5% sodium thiosulfate solution but palladium remained on the column. Silver, gold and palladium were quantitatively eluted with 20 ml of 0.1% thiourea in 0.1 M hydrochloric acid.     

Selective preconcentration of Au(III), Pt(IV) and Pd(II) on silica gel modified with γ-aminopropyltriethoxysilane

Silica gel functionalized by reaction with γ-aminopropyltriethoxysilane was prepared and its adsorption characteirstics for metal ions were studied. This material selectively removes the Au(III), Pt(IV) and Pd(II) chloro complex ions from sample solutions containing Fe(III) and Cu(II) ions by ion exchange.     

Preconcentration of cobalt(II) in natural waters with 1-nitroso-2-naphthol supported on silica gel

A solid chelating material, 1-nitroso-2-naphthol supported on silica gel, provides a rapid and highly selective mean of preconcentrating cobalt(II) fro.     

Synthesis,characterization and susceptibility of bacteria against Sulfamethoxydiazine complexes of copper(II), zinc(II), nickel(II), cadmium(II), chromium(III) and iron(III)

Complexes of sulfamethoxydiazine with Cu(II), Zn(II), Ni(II), Cd(II), Cr(III) and Fe(III) have been synthesized and characterized on the basis of conductivity measurements, elemental analyses, UV, IR, ¹H?NMR and thermal studies. It is shown that sulfamethoxydiazine behaves as a bidentate ligand, binding the metal ion through the sulfonyl oxygen and sulfonamide nitrogen. In vitro susceptibility tests of these complexes against Escherichia coli, Bacillus subtilis, Proteus vulgaris and Staphylococcus aureus were carried out. The results show that the antibacterial activities of the complexes of Zn(II), Cu(II), Cr(III) and Fe(III) are, in general, stronger than that of sulfamethoxydiazine, while the complexes of Cd(II) and Ni(II) are less active.     

Complexes of 1-isonicotinoyl-4-benzoyl-3-thiosemicarbazide with manganese(II), iron(III), chromium(III), cobalt(II), nickel(II), copper(II) and zinc(II)

1-Isonicotinoyl-4-benzoyl-3-thiosemicarbazide (IBtsc) and its Cr^III, Mn^II, Fe^III, Co^II, Ni^II, Cu^II and Zn^II complexes have been prepared and characterized by elemental analyses, magnetic susceptibility measurements, u.v.–vis., i.r., n.m.r. and FAB mass spectral data. The room temperature e.s.r. spectra of the Cr^III, Fe^III and Cu^II complexes yield values, characteristic of octahedral, tetrahedral and square-planar complexes, respectively. The Mössbauer spectra of [Fe(IBtsc-H)Cl₂] at room temperature and at 78 K suggest the presence of high-spin Fe^III. The Ni^II, Cr^III and Cu^II complexes show semiconducting behaviour in the solid state, but the Zn^II complex is an insulator at room temperature. IBtsc and its soluble complexes have been screened against several bacteria, fungi and tumour cell lines.     

Thioacetamide chemically immobilized on silica gel as a solid phase extractant for the extraction and preconcentration of copper(II), lead(II), and cadmium(II)

Thioacetamide immobilized on silica gel was prepared via the Mannich reaction. The extraction and enrichment of copper(II), lead(II), and cadmium(II) ions from aqueous solutions has been investigated. Conditions for effective extraction are optimized with respect to different experimental parameters in both batch and column processes prior to their determination by flame atomic absorption spectrometry (FAAS). The optimum pH ranges for quantitative adsorption are 4.0-8.0, 2.0-7.0, and 5.0-10.0 for Pb(II), Cu(II), and Cd(II), respectively. Pb(II) and Cd(II) can be desorbed with 3 mol/L and 0.1 mol/L HCl/HNO3, and Cu(II) can be desorbed with 2.5% thiourea. The adsorption capacity of the matrix has been found to be 19.76, 16.35, and 12.50 mg/g for Pb(II), Cu(II), and Cd(II), respectively, with the preconcentration factor of approximately equal to 300 for Pb(II) and approximately equal to 200 for Cu(II) and Cd(II). Analytical utility is illustrated in real aqueous samples generated from distilled water, tap water, and river water samples.     

The interference of heteronuclear chromium(III) tartrate complexes in the EDTA titration of cobalt(II), copper(II), zinc(II) and cadmium(II)

When present together in solution, chromium(III) and tartrate can interfere seriously in the titration of Co(II), Cu(II), Zn(II) and Cd(II) with EDTA. Ternary (heteronuclear) tartrate complexes containing Cr(III) and bivalent metal ion in the ratio 1:1 are formed. The conditions for the formation of these complexes have been investigated. Cadmium(II) can be determined without interference by employing potentiometric end-point detection.     

Preconcentration of iron (III), cobalt (II) and copper (II) nitroso-R complexes on tetradecyldimethylbenzylammonium iodide-naphthalene adsorbent

Iron, cobalt and copper form coloured water soluble anionic complexes with disodium 1-nitroso-2-naphthol-3-6-disulphonate (nitroso R-salt). The anionic complex is retained quantitatively as a water insoluble neutral ion associated complex (M-nitroso R-TDBA) on tetradecyldimethylbenzylammonium iodide on naphthalene (TDBA(+)I(-)-naphthalene) packed column in the pH range of: Fe(III): 3.1-6.5, Co: 3.4-8.5 and Cu 5.9-8.0 when their solutions are passed individually over this adsorbent at a flow rate of 0.5-5.0 ml/min. The solid mass consisting of an ion associated metal complex along with naphthalene is dissolved out of the column with 5 ml dimethylformamide/chloroform and metals are determined spectrophotometrically. The absorbance is measured at 710 nm for iron, 425 nm for cobalt and 480 nm for copper. Beers law is obeyed in the concentration range 9.2-82 mug of iron, 425 nm for cobalt cobalt and 3.0-62 mug of copper in 5 ml of final DMF/CHCl(3) solution. The molar absorptivities are calculated to be Fe: 7.58 x 10(3), Co: 1.33 x 10(4) and Cu: 4.92 x 10(4)M(-1)cm(-1). Ten replicate determinations containing 25 mug of iron, 9.96 mug of cobalt and 3.17 mug of copper gave mean absorbances 0.677, 0.450 and 0.490 with relative standard deviations of 0.88, 0.98 and 0.92%, respectively. The interference of large number of metals and anions on the estimations of these metals has been studied. The optimized conditions so developed have been employed for the trace determination of these metals in standard alloys, waste water and fly ash samples.     

Preconcentration of palladium(II) from water with thionalide loaded on silica gel

2-Mercapto-N-2-naphthylacetamide (thionalide) on silica gel is used for rapid preconcentration of μg l^?1 levels of palladium(II) from aqueous solution, followed by atomic absorption spectrometric measurement. In batch experiments, palladium was quantitatively retained on the gel from solutions 5 M in acid to pH 8; equilibrium was achieved within 10 s. The chelating capacity of the gel was 7.5 μmol Pd g^?1 at pH < 4. The effect of flow rate on retention was studied. Palladium retained on the column was completely eluted with 20 ml of 0.2 M thiourea in 0.1 M hydrochloric acid. The palladium concentration in sea water is shown to be < 0.3 μg l^?1.     

Complexes of 2-acetylpyridinesemicarbazone and 2-acetylpyridinethiosemicarbazone with cobalt(II), chromium(III) and copper(II)

Summary The synthesis and characterization of 2-acetylpyridine-semicarbazone (apsc) and 2-acetylpyridinethiosemicarbazone (aptsc) and their complexes with CoCl₂, CrCl₃ and CuCl₂ are reported. These compounds were characterized on the basis of elemental analyses, electronic and i.r. spectra, magnetic moments and conductivity measurements. The molar conductivities in dimethyl formamide indicate the non-ionic nature of the metal chelates. An octahedral structure is proposed for the chromium(III) chelate-complexes, tetrahedral for the copper(II) compounds and tetrahedral or octahedral for the cobalt(II). Apsc and aptsc are bidentate but with different donors, though aptsc is monodentate in its complex with CrCl₃.     

Synthesis and spectral properties of new complexes between glycine and titanium(III), vanadium(III), chromium(III), iron(III), cobalt(II), nickel(II) and copper(II)

Summary Complexes of formula [MCl₃(glyH)₃] (M=Ti, V and Fe) [CrCl₃(glyH)₂H₂O], [MCl₂(glyH)₂(H₂O)₂] (M=Co and Cu) and [NiCl₂(glyH)₃H₂O] have been prepared and characterized by potentiometric curves, chemical analysis, magnetic properties, i.r. and electronic spectral data.     

Polynuclear complexes of chromium(III), copper(II) or nickel(II) with thiocyanate as a bridging ligand

Novel complexes of the type [CuL2]3[Cr(NCS)6]2·xH2O (L = 2,2-bipyridine (bpy), x = 0; L = o-phenanthroline (phen), x = 1), [Cu(dien)]3[Cr(NCS)6]2·3H2O (dien=diethylenetriamine) or [Ni(phen)2]3[Cr(NCS)6]2· 2H2O have been prepared and studied by elemental analyses, i.r. spectra and magnetic measurements. Some of the complexes have been characterized by temperature-dependent magnetic susceptibilities, and weak antiferromagnetic exchange interaction was found for [Cu-(phen)2]3[Cr(NCS)6]2·H2O and [Ni(phen)2]3[Cr(NCS)6]2· 2H2O. Physico-chemical studies account for the polymeric structure, with thiocyanate bridges between Cu or octahedral Ni and octahedral Cr (chromophore CrN6).     

Circular dichroism of the complexes of quinine with copper(II), nickel(II), cobalt(II), chromium(III) and palladium(II) chlorides

The CD spectrum of the complexesQ·2CuCl₂,Q·2CoCl₂,Q·2NiCl₂·8H₂O,Q·3CrCl₃·6H₂O,Q·PdCl₂·3H₂O andQ·2PdCl₂·5H₂O (whereQ=quinine) inDMF orDMSO solution revealsCotton effects in the d-d absorption range. TheCotton effects are relatively strong in the case of Cu(II) and Pd(II) complexes which implies that only in these complexes the hydroxyl group of the quinine molecule possibly participates in the coordination with these metal ions by formation of a chelate ring. The IR spectra of the complexes of Pd(II) are discussed in this respect.

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Circular Dichroismus der Komplexe des Chinins mit Kupfer(II)-, Nickel(II)-, Kobalt(II)-, Chrom(III)- und Palladium(II)-chlorid

Zusammenfassung Die CD-Spektren der KomplexeQ·2CuCl₂,Q·2CoCl₂,Q·2NiCl₂·8H₂O,Q·3CrCl₃·6H₂O,Q·PdCl₂·3H₂O undQ·2PdCl₂·5H₂O, (Q=Chinin), inDMF-bzw.DMSO-Lösungen zeigenCotton-Effekte im Gebiet der d-d-Elektronenübergänge. DieCotton-Effekte sind relativ stark im Falle der Cu(II)- und Pd(II)-Komplexe, was zu der Annahme führt, daß die Hydroxygruppe des Chininmoleküls in diesen Komplexen wahrscheinlich an der Koordination dieser Metallionen durch Chelatringbildung teilnimmt. Unter diesem Aspekt werden die IR-Spektren der Pd(II)-Komplexe untersucht.

     

Thermal study of chelates of Co(II), Cu(II), Ni(II), Cr(III), Mo(III), and Fe(III) with bis(acetylacetone)ethylenediimine on activated silica gel surface

The divalent copper, nickel, cobalt and trivalent chromium, molybdenium and iron chelate compounds derived from bis(acetylacetone) ethylenediimine were grafted on activated silica gel using a batch process in methanolic solution. The sequence of the maximum retention capacity was Cr(III)>Mo(III)>Fe(III)>Co(II)>Ni(II)>Cu(II). Calorimetric titration was employed to study the interaction of activated silica gel with these series of metal chelate compounds. Exothermic enthalpic results were obtained throughout all interactions process. The spontaneity of these systems was reflected in negative and positive free Gibbs energy from entropic values.     

Monomeric dioxouranium(VI), chromium(III), cobalt(II), nickel(II) and copper(II) complexes with primary cellulose acetate (PCA)

Monomeric UO ₂ ²⁺ , Cr^III, CO^II, Ni^II and Cu^II complexes with primary cellulose acetate (PCA) have been prepared and characterized. Infrared,¹H NMR, UV/visible spectroscopy, elemental analysis, therniogravimetry, conductance and magnetic measurements were used to assign the mode of coordination in the isolated species. The investigation revealed that PCA exhibits octahedral coordination with Cr^III, Co^II, Ni^II and a square planar form with Cu^II whereas the UO₂ moiety is virtually linear. PCA acts as a neutral bidentate chelating agent via the two oxygen atoms of the vicinal ester groups in the secondary positions forming a five-membered chelate ring. A comparative study between chelates of PCA and those previously prepared with secondary cellulose acetate (SCA) has been undertaken.     

Complexes of chromium(III), cobalt(II) and copper(II) with sulphur or oxygen and nitrogen donors

Summary The synthesis and characterization of 4-acetyl-pyridinesemicarbazone (4-apsc) and 4-acetylpyridine-thiosemicarbazone (4-aptsc) and their complexes with CrCl₃, CoCl₂ and CuCl₂ are reported. These compounds were characterized on the basis of elemental analyses, electronic and i.r. spectra, magnetic moments and conductivities measurements. The compounds are nonconductors in dimethylformamide. Tentative structures for the complexes are suggested.     

Solid phase extraction of lead (II), copper (II), cadmium (II) and nickel (II) using gallic acid-modified silica gel prior to determination by flame atomic absorption spectrometry

The immobilization of gallic acid on the surface of amino group-containing silica gel phases for the formation of a newly chelating matrix (GASG) is described. The newly synthesized extractant, characterized by the diffuse reflectance infrared Fourier transformation spectroscopy and elemental analysis, was used to preconcentrate Pb(II), Cu(II), Cd(II) and Ni(II). The pH ranges for quantitative sorption and the concentrations of HCl for eluting Pb(II), Cd(II), Cu(II) and Ni(II) were opimized, respectively. The sorption capacity of the matrix has been found to be 12.63, 6.09, 15.38, 4.62mg/g for Pb(II), Cd(II), Cu(II) and Ni(II), respectively, with the preconcentration factor of approximately 200 ( approximately 100 for Cd(II)). The effects of flow rates, the eluants, the electrolytes and cations on the metal ions extraction, as well as the chelating matrix stability and reusability, were also studied. The extraction behavior of the matrix was conformed with Langmuir's equation. The present preconcentration and determination method was successfully applied to the analysis of synthetic metal mixture solution and river water samples. The 3sigma detection limit and 10sigma quantification limit for Pb(II), Cu(II), Cd(II) and Ni(II) were found to be 0.58, 0.86, 0.65, 0.92microg/L and 1.08, 1.23, 0.87, 1.26microg/L, respectively.