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).     

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.     

Antibacterial Co(II), Cu(II), Ni(II) and Zn(II) Complexes of Thiadiazoles Schiff Bases

Schiff bases were obtained by condensation of 2-amino-l,3,4-thiadiazole with 5-substituted-salicylaldehydes which were further used to obtain complexes of the type [M(L)(2)]Cl(2), where M=Co(II), Cu(II), Ni(II) or Zn(II). The new compounds described here have been characterized by physical, spectral and analytical data, and have been screened for antibacterial activity against several bacterial strains such as Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The antibacterial potency of these Schiff bases increased upon chelation/complexation, against the tested bacterial species, opening new aproaches in the fight against antibiotic resistant strains.     

Polymer-Enhanced Crossflow Filtration for Removal of Fe(III), Cu(II), and Cd(II) Ions from Dilute Aqueous Solutions

Abstract

The removal of Fe(III), Cu(II), and Cd(II) ions from aqueous solutions was studied by polymer-enhanced crossflow filtration technique. Alginic acid polymer was used as complexing agents to enhance the retention. Alginic acid/cellulose composite membranes were used in the filtration. In the filtration of metal ion solutions the effects of alginic acid content of the membranes and pH on the percent retention and the permeate flux were examined. The maximum percent retention was found as 98% for 1 × 10^?4 M Fe(III) solution at the flow velocity of 100 mL/min, pH of 3.0, pressure of 60 kPa in the presence of alginic acid as complexing agent by using 0.25 (w/v)% alginic acid/cellulose composite membranes. For 1 × 10^?4 M Cu(II) and Cd(II) solutions the maximum percent retentions were found as 71% and 80% respectively using 0.50 (w/v)% Alginic acid/cellulose composite membranes when the filtration was carried out in the presence of alginic acid at pressure of 10 kPa, flow velocity of 100 mL/min and pH of 7.0.     

A first report of the complexes of 5,11,17,23-tetra-tert-butyl-25,27-diethoxycarboxymethoxy-26,28-dihydroxycalix[4]arene with Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II)

Totally six dinuclear complexes of Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) of calix[4]arene derivatized with two pendants possessing terminal –COOH functions at two of its alternate phenolic –OH groups were synthesized for the first time and were well characterized.     

Protolytic and complexing properties of microcrystalline chitosan with Co(II), Zn(II), and Cu(II) ions

It has been evidenced that microcrystalline chitosan (MCCh) with a determined (by the potentiometric method in nonaqueous medium) degree of deacetylation of 0.87 acts as a polymeric chelating agent with cobalt(II) and zinc(II). The predomination of hydrolytic reactions, in the case of copper(II) ions, has been attributed to a change in crystalline character of the ligand. The protolytic reactions have been studied using the Katchalsky–Spitnik equation. The pH profiles have been shown for Co(II)–MCCh and Zn(II)–MCCh systems and the corresponding equilibrium constants have been determined as well. Both the amino and hydroxyl groups are involved in Co²⁺ complexation, whereas for Zn²⁺, the complexes are formed only via amino nitrogen. © 1995 John Wiley & Sons, Inc.     

Chelation of Cu(II), Zn(II), and Fe(II) by Tannin Constituents of Selected Edible Nuts

The tannin fractions isolated from hazelnuts, walnuts and almonds were characterised by colorimetric assays and by an SE-HPLC technique. The complexation of Cu(II) and Zn(II) was determined by the reaction with tetramethylmurexide, whereas for Fe(II), ferrozine was employed. The walnut tannins exhibited a significantly weaker reaction with the vanillin/HCl reagent than hazelnut and almond tannins, but the protein precipitation capacity of the walnut fraction was high. The SE-HPLC chromatogram of the tannin fraction from hazelnuts revealed the presence of oligomers with higher molecular weights compared to that of almonds. Copper ions were most effectively chelated by the constituents of the tannin fractions of hazelnuts, walnuts and almonds. At a 0.2 mg/assay addition level, the walnut tannins complexed almost 100% Cu(II). The Fe(II) complexation capacities of the tannin fractions of walnuts and hazelnuts were weaker in comparison to that of the almond tannin fraction, which at a 2.5 mg/assay addition level, bound Fe(II) by ~90%. The capacity to chelate Zn(II) was quite varied for the different nut tannin fractions: almond tannins bound as much as 84% Zn(II), whereas the value for walnut tannins was only 8.7%; and for hazelnut tannins, no Zn(II) chelation took place at the levels tested.     

Block copolymer micelles as carriers of transition metal ions Y(III) and Cu(II) and gelation thereof

Poly(ethylene oxide)-block-poly(2-(diethylamino)ethyl methacrylate) (PEO-b-PDEAEMA) diblock copolymer was synthesized by anionic polymerization, whose molecular structure was characterized by ¹H NMR and size exclusion chromatography (SEC). The diblock copolymer self-assembled into micelles in nonacid aqueous solution with PEO and PDEAEMA as corona and core respectively. By virtue of the coordinating property of PDEAEMA block to metal ions, the resultant micelles were then used as carriers to load metal ions Y(III) and Cu(II) in the micellar core. The morphology and stability of the metal loaded micelles were characterized by dynamic light scattering (DLS), atomic force microscopy (AFM) and transmission electron microscopy (TEM). The metal loading amounts were determined by elemental analyses, UV spectrometry and titrimetric analysis. In addition, the Y(III) loaded micelles were demonstrated to complex with α-cyclodextrins and form supramolecular hydrogels in-situ. The metal loaded micelles and the resultant supramolecular hydrogels will have potential application for cancer internal radiotherapy.     

Synthesis, Characterization and Biological Evaluation of Co(II), Cu(II), Ni(II) and Zn(II) Complexes With Cephradine

Some Co(II), Cu(II), Ni(II) and Zn(II) complexes of antibacterial drug cephradine have been prepared and characterized by their physical, spectral and analytical data. Cephradine acts as bidentate and the complexes have compositions, [M(L)(2)X(2)] where [M = Co(II), Ni(II) and Zn(II), L = cephradine and X = Cl(2)] showing octahedral geometry, and [M(L)(2)] where [M = Cu(II), L = cephradine] showing square planar geometry. In order to evaluate the effect of metal ions upon chelation, eephradine and its complexes have been screened for their antibacterial activity against bacterial strains, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa.     

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.     

Synthesis, characterization, and properties of polychelates of poly(maleic acid-co-olefin) with Cu(II), Co(II), Ni(II), and Zn(II)

SUMMARY Polychelates of poly(maleic acid-co-olefin) with Cu(II), Co(II), Ni(II), and Zn(II) metal ions are synthesized. These compounds are characterized by FT IR, UV-vis spectroscopy, and thermal analysis. The electrical conductivity measurements are carried out. These demonstrate that at temperature close to 130°C the electrical conductivity increased to values near to the semiconductor range. The PM3 calculations are also carried to study the geometry of the polychelates. Received: 1 November 2000/Revised version: 20 March 2001/Accepted: 21 March 2001     

Conductometric studies of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) tetrafluoroborates in N,N—dimethylacetamide solutions

Results are reported for the molar conductivities at 25°C of N,N—dimethylacetamide (DMA) solutions of Bu₄NBF₄ and Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) tetrafluoroborates. The limiting molar conductivities of [M(DMA)₆]²⁺ (M  MN, Co, Ni, Cu, Zn) and BF^?₄, as well as association constants for Co(BF₄)₂ in DMA solutions have been calculated. The slight differences between conductometric curves of different metal ions are discussed.     

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.     

Potentiometric Studies on Ternary Complex Formation between Cu(II), Ni(II), Zn(II), Cd(II), nitrilotriacetic acid and amino acid

The formation of ternary complexes of the type MAB (where M = Cu(II), Ni(II), Zn(II) or Cd(II); A = nitrilotriacetic acid and B = glycine, α-alanine or dl-aspartic acid) has been shown by potentiometric studies. The nature of titration curves indicates that the secondary ligand B is added stepwise to the initially formed metal nitrilotriacetates. The formation constants (log K_MAB) and the free energies of formation (ΔF°) of the mixed complexes have been calculated at 25 ± 1 °C and m̈ = 0.10 (KNO₃) at different pH values. The formation constants of the resulting 1:1:1 ternary complexes follow the order Cu(II) > Ni(II) > Zn(II) > Cd(II).     

Preparation and characterization of magnetic chelating resin based on chitosan for adsorption of Cu(II), Co(II), and Ni(II) ions

Cross-linked magnetic chitosan–diacetylmonoxime Schiff’s base resin (CSMO) was prepared for adsorption of metal ions. CSMO obtained was investigated by means of scanning electron microscope (SEM), FTIR, ¹H NMR, wide-angle X-ray diffraction (WAXRD), magnetic properties and thermogravimetric analysis (TGA). The adsorption properties of cross-linked magnetic CSMO resin toward Cu²⁺, Co²⁺ and Ni²⁺ ions were evaluated. Various factors affecting the uptake behavior such as contact time, temperature, pH and initial concentration of the metal ions were investigated. The kinetics was evaluated utilizing the pseudo-first-order and pseudo-second-order. The equilibrium data were analyzed using the Langmuir, Freundlich, and Tempkin isotherm models. The adsorption kinetics followed the mechanism of the pseudo-second-order equation for all systems studied, evidencing chemical sorption as the rate-limiting step of adsorption mechanism and not involving a mass transfer in solution. The best interpretation for the equilibrium data was given by Langmuir isotherm, and the maximum adsorption capacities were 95 ± 4, 60 ± 1.5, and 47 ± 1.5 mg/g for Cu²⁺, Co²⁺ and Ni²⁺ ions, respectively. Cross-linked magnetic CSMO displayed higher adsorption capacity for Cu²⁺ in all pH ranges studied. The adsorption capacity of the metal ions decreased with increasing temperature. The metal ion-loaded cross-linked magnetic CSMO were regenerated with an efficiency of greater than 84% using 0.01–0.1 M ethylendiamine tetraacetic acid (EDTA).     

Polymer-metal complexes: Synthesis, characterization, and properties of poly(maleic acid) metal complexes with Cu(II), Co(II), Ni(II), and Zn(II)

SUMMARY Polymer metal complexes of poly(maleic acid) and Cu(II), Co(II), Ni(II), and Zn(II) were synthesized. Elemental analysis, as well as magnetic, spectral and thermal properties, in addition to electrical conductivities of the chelates were investigated, and possible structures have been assigned to the polychelates. Semi-empirical calculations at the PM3 level were carried out on the geometrical arrangement of the polychelates. Received: 19 November 1999/Revised version: 22 March 2000/Accepted: 31 March 2000     

The influence of Cu,Fe, Ni,Pb and Zn on gum formation in the Brazilian automotive gasoline

In this research work, the effect of different concentrations of copper, iron, lead, zinc and nickel ions on the tendency for gum formation in gasohol fuel is investigated. For that purpose, a gasohol sample has been doped with these five metals ions at concentration levels of 0.25, 1.0, 2.0 and 3.0 μg ml^− 1. Washed gum content tests have been carried out using ASTM D 381 on samples stored for 7, 14, and 28 days. The results show that gum formation is strongly affected by Cu and Fe, with a much weaker effect from Ni and Zn, and an almost negligible effect from Pb. A variance analysis (ANOVA) of the experimental results shows that an increase in metal concentration strongly increases the rate of gum formation for all metal ions investigated, particularly Cu and Fe, while an increase in storage time has only a much weaker effect, being negligible for Zn.     

Extraction of Cu(II), Ni(II), and Al(III) with the Deep Eutectic Solvent D2EHPA/Menthol

Theoretical Foundations of Chemical Engineering - A new hydrophobic deep eutectic solvent (HDES) based on di(2-ethylhexyl)phosphoric acid and menthol has been proposed for the extraction of...     

Liquid-Phase Catalytic Hydroxylation of Phenol Using Cu(II), Ni(II) and Zn(II) Complexes of Amidate Ligand Encapsulated in Zeolite-Y as Catalysts

Copper(II), nickel(II) and zinc(II) complexes of amidate ligand 1,2-bis(2-hydroxybenzamido)ethane(H₂hybe) encapsulated in the super cages of zeolite-Y have been prepared and characterized by spectroscopic studies and thermal as well as X-ray diffraction (XRD) patterns. These complexes catalyze the liquid-phase hydroxylation of phenol with H₂O₂ to catechol as a major product and hydroquinone as a minor product. Considering the concentration of substrate and oxidant, amount of catalyst, temperature of the reaction and volume of solvent, a best-suited reaction condition has been optimized to get maximum hydroxylation. Under the optimized reaction conditions, [Cu(hybe)]-Y has shown the highest conversion of 40% after 6h, which is followed by [Ni(hybe)]-Y with 37% conversion and [Zn(hybe)]-Y has shown the poorest performance with 33% conversion. All these catalysts are more selective towards catechol formation (90%), irrespective of their catalytic performance.