Occlusion of transition metal ions by new adsorbents synthesized from plant polyphenols and animal fibrous proteins

Removing and collecting heavy and rare metal ions from industrial effluents and waste aqueous solutions are improtant problems. Our previous studies showed that animal fibrous proteins (AFPs) such as hen eggshell membrane, chicken feather (CF), wool, and silk were stable and insoluble proteins and had an excellent ability to bind not only hard (Mn²⁺ and Fe³⁺) but alsosoft (Ag⁺, Au⁺, Pd²⁺, Pt²⁺, and Hg²⁺) acids from aqueous solutions. In this study, we syntheszed some adsorbents for transition (Cr⁶⁺, Mn²⁺, Co²⁺, Ni²⁺, and Cu²⁺) and heavy (Cd²⁺) metalions from AFPs (gelatin, CF, and wool) and plant polyphenols (lignin and tannin) by heating a mixture of AFPs and plant polyphenols under acidic conditions. In batch experiments, pH profile, time dependency, and isotherm analysis were performed to determine binding properties of adsorbents for transition and heavy metal ions. Columnexperiments were also performed to removecopper ion from aqueous solution. The results showed that the new adsorbents were effective for collecting and removing transition and heavy metal ions from aqueous solutions.     

Potentiometric and thermodynamic studies of 3-methyl-1-phenyl-{p-[N-(pyrimidin-2-yl)-sulfamoyl]phenylazo}-2-pyrazolin-5-one and its metal complexes

The dissociation constants of 3-methyl-1-phenyl-{p-[N-(pyrimidin-2-yl)sulfamoyl]phenylazo}-2-pyrazolin-5-one and metal-ligand stability constants of its complexes with some transition metal ions have been determined potentiometrically in 0.1 M-KCl and ethanol—water mixture (30 vol. %). The order of the stability constants of the formed complexes increases in the sequence Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, La³⁺, Hf³⁺, UO ₂ ²⁺ , Zr⁴⁺. The effect of temperature was studied and the corresponding thermodynamic parameters (ΔG, ΔH, and ΔS) were derived and discussed. The dissociation process is nonspontaneous, endothermic, and entropically unfavourable. The formation of the metal complexes was found to be spontaneous, exothermic, and entropically favourable. Abstracted from his M.Sc. Thesis.     

Synthesis,characterization, molecular modelling and biological activity of 2‐(pyridin‐1‐ium‐1‐yl) acetate and its Cu2+, Pt4+, Pd2+, Au3+ and Nd3+ complexes

A new series of Cu²⁺, Pt⁴⁺, Pd²⁺, Au³⁺ and Nd³⁺ complexes derived from 2‐(pyridin‐1‐ium‐1‐yl) acetate have been synthesized and characterized using elemental analyses, spectral (infrared (IR), UV–visible, mass, ¹³C NMR and ¹H NMR), magnetic and thermal measurements. IR results suggest that the ligand acts in a neutral monodentate fashion in all complexes. Octahedral geometry is proposed for Cu²⁺ and Pt⁴⁺ complexes and square‐planar for Pd²⁺ and Au³⁺ complexes. The bond lengths, bond angles, and HOMO and LUMO were calculated. Superoxide dismutase‐like radical scavenger activity and cytotoxic activity of the isolated complexes on HepG2 liver cancer cells have been screened. Ligand and complexes (Pt⁴⁺ and Nd³⁺) exhibit potent antioxidant activity upon coordination while Cu²⁺ and Au³⁺ complexes do not show superoxide dismutase‐like radical scavenger activity. The cytotoxic activity assay against HepG2 cell line proves that the ligand and its Pt⁴⁺ complex have a high cytotoxic activity, while the other complexes showed no cytotoxic activity. Copyright © 2014 John Wiley & Sons, Ltd.     

Effect of non-aqueous solvents on stoichiometry and selectivity of complexes formed between 4′-nitrobenzo-15-crown-5 with Fe3+, Y3+, Cd2+, Sn4+, Ce3+ and Au3+ metal cations

The complexation processes between Fe³⁺, Y³⁺, Cd²⁺, Sn⁴⁺, Ce³⁺ and Au³⁺ metal cations with macrocyclic ligand, 4′-nitrobenzo-15-crown-5 (4′NB15C5), were studied in acetonitrile (AN), methanol (MeOH) and nitromethane (NM) solvents at different temperatures using conductometric method. The conductance data show that the stoichiometry of the complexes formed between this macrocyclic ligand and Cd²⁺, Au³⁺ cations is 1: 1 (ML), but in the case of Fe³⁺, Y³⁺ and Ce³⁺ metal cations, 2: 1 (M₂: L) and 2: 2 [M₂: L₂] complexes are formed in nitromethane solutions. The results show, that the selectivity of 4’NB15C5 for the studied metal cations in methanol solutions at 15°C is: Sn⁴⁺ > Cd²⁺ > Y³⁺ > Fe³⁺ ∼ Ce³⁺ > Au³⁺, but in the case of acetonitrile, the stability order was found to be: Y³⁺ > Au³⁺ > Fe³⁺ > Cd²⁺. The values of stability constants of the 1: 1 [M: L] complexes were determined from conductometric data using a GENPLOT computer program. The values of thermodynamic parameter (ΔH _c ^o and ΔH _c ^o) for formation of the complexes were obtained from temperature dependence of the stability constants, using the van’t Hoff plots. The results show that the values of standard enthalpy (ΔH _c ^o) and standard entropy (ΔH _c ^o) change with the nature of the non aqueous solvents.     

Transition metal ions in black tea: an electron paramagnetic resonance study

Tea (Camellia Sinensis) is the most widely consumed beverage in the world and is known to have therapeutic, antioxidant and nutritional effects. It contains dimeric flavanols and polyphenols which are known as the most important organic compounds in tea infusions, and can make strong and stable complexes with metal ions. In this study, we carried out a series of electron paramagnetic resonance experiments on well-known paramagnetic transition metal ions, namely Mn²⁺, Fe³⁺, Cu²⁺, VO²⁺, and Cr³⁺ doped in black tea cultivated along the shore of Black Sea, Turkey, to see the effects and structures formed.     

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。     

螯合树脂研究——Ⅺ.一类新的氨基二硫代甲酸型螯合树脂的合成及吸附性能

 本文报道了以多乙烯多胺为主链的巯基胺树脂与二硫化碳反应,合成了四种新型的氨基二硫代甲酸型螯合树脂,这类树脂对贵金属具有高的吸附容量和优良的吸附选择性。并通过红外光谱和X光电子能谱研究树脂及其金属螫合物。     

Thermodynamics of citrate complexation with Mn<Superscript>2+</Superscript>, Co<Superscript>2+</Superscript>, Ni<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript> ions

Isothermal titration calorimetry has been used to determine the stoichiometry, formation constants and thermodynamic parameters (ΔG ^o, ΔH, ΔS) for the formation of the citrate complexes with the Mn²⁺, Co²⁺, Ni²⁺ and Zn²⁺ ions. The measurements were run in Cacodylate, Pipes and Mes buffer solutions with a pH of 6, at 298.15 K. A constant ionic strength of 100 mM was maintained with NaClO₄. The influence of a metal ion on its interaction energy with the citrate ions and the stability of the resulting complexes have been discussed.     

Kinetics of the mediatory reduction ofgem-dichlorocyclopropanes

The effect of the nature of organic electron transfer agents and of Pt^II, Pd^II, Rh^II, Co^II, Ni^II, Cu^II, Cr^III, Mn^II, Ti^III, V^III, Zn^II, and Ag^I metal ions on the kinetics of the homogeneous reduction ofgem-dichlorocyclopropanes has been studied. Pt^II, Pd^II, Rh^III, Co^II, and Ni^II ions accelerate this process, V^III and Ag^I ions exert practically no effect on the reduction rate, and the rest of the metal ions exhibit inhibitor properties.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1407–1410, August, 1993.     

Catalytic decomposition of aliphatic peroxy acids

The catalytic decomposition of peroxy acids is studied in various solvents in the presence of manganese, cobalt, chromium, nickel, and copper acetates and cerium benzoate. The catalytic activity of the salts in peroxy acid decomposition decreases in the order Mn²⁺ > Co²⁺ > Ce³⁺ > Cr³⁺ > Ni²⁺ > Cu²⁺. The apparent activation energies of the catalytic decomposition of peroxydecanoic acid range between 45.9 and 88.0 kJ/mol. The reaction medium has an effect both on the apparent rate constant and on the activation energy of the reaction. The reaction mechanism includes the fast formation of a catalyst-peroxy acid intermediate complex, which decomposes to release a catalyst molecule and forms the reaction products. The oxidation state of the metal ion of the catalyst can change. The introduction of compounds capable of forming complexes with metal ions of the catalyst substantially slows down the catalytic decomposition.     

Potentiometric and Thermodynamic Studies of 4-Sulfamethazineazo-3-methyl-1-phenyl-2- pyrazolin-5-one and Its Metal Complexes

Proton–ligand dissociation constants of 4-sulfamethazineazo-3-methyl-1-phenyl-2- pyrazolin-5-one (SMP) and metal–ligand stability constants of its complexes with bivalent metal ions (Mn²⁺, Co²⁺, Ni²⁺ , Cu²⁺, and Zn²⁺) have been determined potentiometrically in 0.1 M KCl, and a 40% (v/v) ethanol–water mixture. The order of the stability constants of the complexes was found to be Mn²⁺ < Co < Ni < Cu < Zn. The dissociation constants, pK ^H, of SMP and the stability constants, log K, of its complexes were determined at different temperatures and the corresponding thermodynamic parameters ( G, H, and S) were derived and discussed. The dissociation process is nonspontaneous, endothermic, and entropically unfavorable. The formation of the complexes were found to be spontaneous, endothermic, and entropically favorable.     

ADDUCTS OF THEOBROMINE WITH 3d METAL PERCHLORATES

Abstract

Adducts of theobromine (tbH) with 3d metal perchlorates (Mⁿ⁺ = Cr^3-. Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn^2- I here prepared by refluxing mixtures of the Iigand and a metal salt in ethyl acetate-triethyl orthoformate. The new complexes invariably involve 2: 1 molar ratios of tbH to metal ion and are apparently monomeric with terminal tbH ligands binding riaa ring nitrogen (N9 or Nl). The Mn²⁺, Cu²⁺ and Zn^2- complexes are distorted tetrahedral, involving tuo tbH and two unidentate perchlorato ligands in the first coordination sphere of the metal ion. The remaining metal(II) complexes (Fe, Co, Ni) were obtained as monohydrates. These compounds are pentacoordinated of the [M(tbH)₂(OClO₃)₂(OH₂)] type, containing one aqua ligand in addition to the tbH and perchlorato ligands. The Cr³⁺ and Fe³⁺ complexes are low-symmetry hexacoordinated, with two tbH ligands. two unidentate and one bidentate chelating perchlorate Iigands.     

Determination of the complex formation constants for some water-soluble polymers with trivalent metal ions by differential pulse polarography

The formation of metal complexes between water-soluble polymers, poly(vinyl alcohol) [PVA], poly(N-vinylpyrrolidone) [PVP], poly(acrylamide) [PAAm] and poly(ethylene oxide) [PEO] with trivalent metal ions, Fe³⁺, Cr³⁺, and V³⁺ were studied by using differential pulse polarography (DPP). The general experimental observation is the shift of totally reversible reduction peaks (M³⁺+Hg+e^–M²⁺+Hg) towards more negative potentials when the complexing water-soluble polymers are added to the solution of trivalent metal ions. The negative shift in potential permitted the determination of complex formation constants (K_f) between trivalent metal ions and water soluble polymers. The complex formation constants for Fe³⁺, Cr³⁺, and V³⁺ ions with these polymers increased in the order of V³⁺>Cr³⁺>Fe³⁺.     

Study of the thermal decomposition of cellulose-hyphan and its complexes with some transition and indium metal ions

The studied complexes formed by the chelating ion exchanger were characterized by reflectance and infrared spectrometry. The thermal degradation of pure cellulose-hyphan (CH) and its complexes with Hg²⁺, In³⁺, Cr³⁺, Mo⁴⁺ and Mn²⁺ under an atmosphere of air has been studied using thermal gravimetry (TG) and differential thermal analysis (DTG). The results showed that four different stages are accompanying the decomposition of (CH) and its complexes with the studied metals. These stages were found to be affected by the presence of the investigated metal ions. On the bases of the applicability of a non-isothermal kinetic equation it was found to be a first-order reaction with the rate of degradation,k, ranging from 8.3·10^?5 to 6.2·10^?3 for (CH) and from 1.7·10^?5 to 6.6·10^?3 s^?1 for its complexes. The activation energy,E _a, the entropy change, ΔS°, the enthalpy change, ΔH° and Gibbs free energy, ΔG° are calculated by applying the rate theory of the first-order reaction. The effect of the different central metal ions on the calculated thermodynamic parameters is discussed.     

The spectrophotometric and titrimetric determination of gold with ferroin as reagent

A spectrophotometric and a photometric titration method in a two-phase system for the determination of gold with ferroin is reported. Both methods are rapid and reproducible with an accuracy of ±1%. In the spectrophotometric determination Co²⁺, Cu²⁺, Ni²⁺ , Fe³⁺, Zn²⁺, Mn²⁺ and Cr³⁺ do not interfere with the determination of gold and Pt⁴⁺, Pd²⁺, Hg²⁺, Ir⁴⁺ and Os⁴⁺ can be tolerated up to a ratio of 1:1. The titrations can also be carried out in the presence of a number of diverse ions, e.g. Ni²⁺, Cu²⁺, Co²⁺, Fe³⁺, Zn²⁺, Cr³⁺, Mn²⁺, without interference; the platinum metals and Hg²⁺ cause interference but, by the use of the spectrophotometric procedure, this can be reduced.     

Chromium(III), manganese(II), iron(III), cobalt(II), nickel(II) and copper(II) complexes with a pentadentate, 15-membered new macrocyclic ligand

Complexes of Cr^III, Mn^II, Fe^III, Co^II, Ni^II and Cu^II containing a macrocyclic pentadentate nitrogen–sulphur donor ligand have been prepared via reaction of a pentadentate ligand (N₃S₂) with transition metal ions. The N₃S₂ ligand was prepared by [1 + 1] condensation of 2,6-diacetylpyridine with 1,2-di(o-aminophenylthio(ethane. The structures of the complexes have been elucidated by elemental analyses, molar conductance, magnetic susceptibility measurements, i.r., electronic and e.p.r. spectral studies. The complexes are of the high spin type and are six-coordinate.     

Effect of a metal ion on intramolecular spin exchange in spin-labeled complexes

The characteristic features of intramolecular spin exchange in 14 complexes of Ag^I, Hg^II, Ni^II, Pd^II, Pt^II, Au^III, and Pt^IV with spin-labeled ligands were studied by ESR spectroscopy. The measured values of the exchange integral ‖J‖ and the differences between the enthalpies of the efficient conformations (ΔH) were compared with the electronic polarization (refraction)R _f of the Ni^II, Pd^II, and Pt^II ions and Klopman's rigidity parameters σ_K, which characterize the total polarazibility of the ions and the degree of covalence of the bond between the metal atom and the donor atom of the ligand, respectively. Delocalization of the electron spin density and the efficiency of spin exchange are determined by the relative contributions of the s, p, and d orbitals, which produce the overlap integral of wave functions, ‖J‖, and by the geometric features of the coordination polyhedron, which affect the mutual orientation of the N−O fragments. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2005–2009, October, 1999.     

冠醚聚合物的研究 Ⅱ.以聚硫醚为主链的硫杂冠醚聚合物的合成及其络合性能

 本文报道了一种合成硫杂冠醚聚合物的新方法。以聚(2′-氯乙基-2,3-环硫丙基醚)为预聚物与二巯基化合物通过大分子反应直接环化,一步法合成了四种以聚硫醚为主链的新型硫杂冠醚聚合物(PD1-PD4)。并测定了它们对Ag⁺、Au³⁺)、Pd²⁺、Pt⁴⁺、Cu²⁺、Hg²⁺、Zn²⁺、Cd²⁺、Pb²⁺、Mg²⁺、K⁺、Ns⁺等金属离子的络合性能。结果表明:它们除不络合K⁺、Na⁺、Mg²⁺、Pb²⁺外,对其它八种离子有不同程度的络合,其中对Ag⁺、Au³⁺、Pd²⁺等贵金属离子的络合容量较高。     

Preconcentration and Determination of Copper(II) by Novel Solid-Phase Extraction and High-Resolution Continuum Source Flame Atomic Absorption Spectrometry

Amberlite XAD-4 modified with N-para-anisidine-3,5-di-tert-butylsalicylaldimine was investigated as a new chealting sorbent for the selective separation and preconcentration of Cu(II). The metal ion was retained by chemical sorption on the modified resin, eluted by hydrochloric acid, and determined by high-resolution continuum source flame atomic absorption spectrometry. The prepared resin was characterized for the solid-phase extraction of Cd²⁺, Co²⁺, Cr³⁺, Cu²⁺, Fe³⁺, Mn²⁺, Ni²⁺, Pb²⁺, and Zn²⁺ in a column. The influence of the pH, the mass of solid phase, eluent, flow rate, and sample volume was optimized. Using the optimum conditions, only Cu(II) showed quantitative sorption at the 95% confidence level, and the recoveries of the other metal ions were below 80%. A preconcentration factor 125 was obtained for Cu(II) with a limit of detection of 0.56?µg?L^?1. The method was used for the determination of Cu(II) in tap water, river water, tomato leaves, and fish. The relative standard deviation and the relative error were lower than 7%.     

A Conductometric Study of Complexation Reactions Between Dibenzo-18-Crown-6 (DB18C6) with Cu2+, Zn2+, Tl+ and Cd2+ Metal Cations in Dimethylsulfoxide–Ethylacetate Binary Mixtures

The complex formation between Cu²⁺, Zn²⁺, Tl⁺ and Cd²⁺ metal cations with macrocyclic ligand, dibenzo- 18-crown-6 (DB18C6) was studied in dimethylsulfoxide (DMSO)–ethylacetate (EtOAc) binary systems at different temperatures using conductometric method. In all cases, DB18C6 forms 1:1 complexes with these metal cations. The stability constants of the complexes were obtained from fitting of molar conductivity curves using a computer program, Genplot. The non-linear behaviour which was observed for variations of log K _f of the complexes versus the composition of the mixed solvent was discussed in terms of changing the chemical and physical properties of the constituent solvents when they mix with one another and, therefore, changing the solvation capacities of the metal cations, crown ether molecules and even the resulting complexes with changing the mixed solvent composition. The results show that the selectivity order of DB18C6 for the metal cations in pure ethylacetate and pure dimethylsulfoxide is: Tl⁺ > Cu²⁺ > Zn²⁺ > Cd²⁺ but the selectivity order is changed with the composition of the mixed solvents. The values of enthalpy changes (ΔH°_C) for complexation reactions were obtained from the slope of the van’t Hoff plots and the changes in standard enthalpy (ΔS°_C) were calculated from the relationship: ΔG°_C,298.15=ΔH°_C − 298.15 ΔS°_C. The obtained results show that in most cases, the complexes are enthalpy stabilized, but entropy destabilized and the values of ΔH°_C and ΔS°_C depend strongly on the nature of the medium.