Quantitative Trennung von Schwermetallen mit Chelataustauschern auf der Basis von Polystyrol

Zusammenfassung Die Trennung und Isolierung von folgenden Schwermetallen bei einem hohen Überschuß an Fremdionen mit Hilfe neuer selektiver Chelataustauscher wird beschrieben: Cu²⁺/Zn²⁺, Cu²⁺/Pb²⁺, Ag⁺/Cu²⁺, Ag⁺/Pb²⁺, Hg²⁺/Zn²⁺, Hg²⁺/Cd²⁺; Abtrennung von Hg²⁺. Unter gleichen Bedingungen war mit dem handelsüblichen Austauscher Dowex A-1 keine Trennung möglich.

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Quantitative separation of heavy metals by means of chelating exchangers based on polystyrol

Summary The separation and isolation of the following heavy metals in presence of a high excess of foreign ions by means of new selective chelating exchangers is described: Cu²⁺/Zn²⁺, Cu²⁺/Pb²⁺, Ag⁺/Cu²⁺, Ag⁺/Pb²⁺, Hg²⁺/Zn²⁺, Hg²⁺/Cd²⁺; separation of Hg²⁺. Under the same conditions no separation could be achieved by the ion-exchanger Dowex A-1.

     

Simultaneous Titration of Ternary Mixtures of Pb(II), Cd(II) and Cu(II) with Potentiometric Electronic Tongue Detection

An automatic titration method is reported to resolve ternary mixtures of transition metals (Pb²⁺, Cd²⁺ and Cu²⁺) employing electronic tongue detection and a reduced number of pre‐defined additions of EDTA titrant. Sensors used were PVC membrane selective electrodes with generic response to heavy‐metals, plus an artificial neural network response model. Detection limits obtained were ca. 1 mg L^?1 for the three target ions and reproducibilities 3.0 % for Pb²⁺, 4.1 % for Cd²⁺ and 5.2 % for Cu²⁺. The system was applied to contaminated soil samples and high accuracy was obtained for the determination of Pb²⁺. In the determination Cd²⁺ and Cu²⁺, sample matrix showed a significant effect.     

A reactive electrode (reactrode) for the voltammetric determination of heavy metals in laboratories and for use as a passive monitor in remote analysis

The use of a reactive electrode (reactrode) consisting of graphite, a solid ion exchanger (HYPHAN) and paraffin for the batch analysis of Cd²⁺, Cu²⁺, Pb²⁺ and Hg²⁺ in aqueous samples and as a passive monitor for these metal ions is described. The metal ions are accumulated on the reactrode surface at an open-circuit potential in an ion-exchange reaction. After the accumulation, the ion exchanger-bonded metal ions are reduced to the metals which remain on the electrode surface. In a following step, the metals are anodically dissolved which is recorded by differential-pulse voltammetry. The 3s detection limits for the analysis of drinking water are: 1.1×10^-7 mol/l for Pb²⁺, 5×10^-8 mol/l for Hg²⁺ and 2.4×10^-7 mol/l for Cu²⁺.The reactrode developed can be used for the passive monitoring of heavy metals in aqueous streams if the reactrode is mounted in a wall-jet cell which is part of a flow-through system. Using this arrangement, it has been possible to determine Hg²⁺, Cu²⁺ and Pb²⁺ in drinking water after 20 hours of accumulation.     

Calix[4]Resorcinarene Macrocycles Interactions with Cd2+, Hg2+, Pb2+, and Cu2+ Cations: A QCM‐I and Langmuir Ultra‐thin Monolayers Study

Stable ultra‐thin Langmuir monolayers of calix[4]resorcinarene derivatives, namely: C‐dec‐9‐enylcalix[4]resorcinarene‐O‐(R+)‐α‐methylbenzylamine (Ionophore I ), and C‐dec‐9‐enylcalix[4]resorcinarene‐O‐(S‐)‐α‐methylbenzylamine (Ionophore II ), were prepared at the air‐water interface. Their interactions with a series of heavy metals (HM) ions (Cu²⁺, Pb²⁺, Hg²⁺ and Cd²⁺) present in the aqueous subphase were investigated by measuring surface pressure‐area isotherms, at different concentrations. The surface pressure‐area (Π‐A) isotherms were stable and demonstrated the HM amounts influence on the limiting area (A_lim) values, therefore confirming the examined macrocycles capability to host the metallic toxicants. Additionally, a HM concentration dependence was realized and interpreted by a selective tendency of both ionophores towards Cu²⁺ and Cd²⁺ ions over Pb²⁺ and Hg²⁺, especially at high concentrations. The HM ions interactions with the applied calix[4]resorcinarene Langmuir ultra‐thin monolayers were interpreted based on the Gibbs‐Shishkovsky adsorption equation. Moreover, quartz crystal microbalance with impedance measurement (QCM‐I), was applied for the detection of HM ions in solutions. The QCM‐I results showed the effectiveness of the coated QCM‐I crystals in detecting the ions at different concentrations. The detection limit values were in the order of 0.16, 0.3, 0.65, 1.1 ppm (Ionophore I), as well 0.11, 0.45, 0.2, 0.89 (Ionophore II) for the Cu²⁺, Pb²⁺, Hg²⁺ and Cd²⁺ cations, respectively. Additionally, a selective tendency of both ionophores towards copper ions was shown.     

Effect of Toxic Metal Ions on Photosensitized Singlet Oxygen Generation for Photodegradation of Polyaromatic Hydrocarbon Derivatives and Inactivation of Escherichia coli

Here, we report an experimental study of the effect of toxic metal ions on photosensitized singlet oxygen generation for photodegradation of PAH derivatives, Anthracene‐9,10‐dipropionic acid disodium salt (ADPA) and 1,5‐dihydroxynapthalene (DHN) and photoinactivation of Escherichia coli bacteria by using cationic meso‐tetra(N‐methyl‐4‐pyridyl)porphine tetrachloride (TMPyP) as a singlet oxygen photosensitizer. Three s‐block metals ions, such as Na⁺, K⁺ and Ca²⁺ and five toxic metals such as Cd²⁺, Cu²⁺, Hg²⁺, Zn²⁺ and Pb²⁺ were studied. The s‐block metal ions showed no change in the rate of photodegradation of ADPA or DHN by TMPyP, whereas a dramatic change in the photodegradation of ADPA and DHN was observed in the presence of toxic metals. The maximum photodegradation rate constants of ADPA and DHN were observed for Cd²⁺ ions [(3.91 ± 0.20) × 10^?3 s^?1 and (7.18 ± 0.35) × 10^?4 s^?1, respectively]. Strikingly, the photodegradation of ADPA and DHN was almost completely inhibited in the presence of Hg²⁺ ions and Cu²⁺ ions. A complete inhibition of growth of E. coli was observed upon visible light irradiation of E. coli solutions with TMPyP and toxic metal ions particularly, Cd²⁺, Hg²⁺, Zn²⁺ and Pb²⁺ ions, except for Cu²⁺ ions where a significantly slow inhibition of E. coli's growth was observed.     

Synthesis of a Dithiocarbamate Chelate Resin and Its Oxidized form and Their Adsorption Properties for Heavy Metal Ions

A series of macroporous dithiocarbamate chelate resins, III and V, and an oxidized resin, VI, with high adsorption capacity were prepared. The influence of various reaction conditions of amination, dithiocarboxylation, and oxidation were examined. The structure and the conversion of functional groups of resins were confirmed by IR spectra and elemental analysis. The adsorption capacities of Resin II for Hg²⁺, Cu²⁺, Zn²⁺, and Cd²⁺ are 4.40, 2.44, 1.77, and 1.36 mmol/g, respectively. The adsorption capacities of Resins V and VI for Cu²⁺. Zn²⁺, Ni²⁺, Co³⁺, Ag⁺, Hg²⁺, Cd²⁺, Pb²⁺, and Au³⁺ are 4.07–0.51 and 3.81–0.59 meq ion/g, respectively. The adsorption rate and the influence of pH on the adsorption percentage of the resins for metal ions were examined. Noble metal, transitional metal, and heavy metal ions can be quantitatively adsorbed by the resins. The adsorbed Cu²⁺, Pb²⁺, Cd²⁺, Co³⁺, and Ni²⁺ can be quantitatively eluted with 5N HNO₃, and the presence of large amounts of Ca²⁺, Mg²⁺, Fe³⁺, and Al³⁺ did not interfere.     

Complexation of metal ions with double-armed diazadithia lariat ether carrying anthracene moieties in acetonitrile–dioxane

A new 14-membered crown ether with nitrogen–sulfur donor atom carrying two anthryl groups was designed and synthesized by the reaction of the corresponding macrocyclic compound and 9-(chloromethyl) anthracene. The influence of metal cations such as Al³⁺, Zn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Mn²⁺, Cu²⁺, Cd²⁺, Hg²⁺ and Pb²⁺ on the spectroscopic properties of the ligand was investigated in acetonitrile–dioxane solution (1/1) by means of absorption and emission spectrometry. The results of spectrophotometric titration experiments disclosed the complexation stoichiometry and complex stability constant of the novel ligand with Fe²⁺, Fe³⁺, Al³⁺, Cd²⁺, Cu²⁺, Zn²⁺, Pb²⁺ and Hg²⁺ cations. Absorption spectra show isobestic points in the spectrophotometric titration of these cations. The presence of excess of Al³⁺, Zn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Mn²⁺, Cu²⁺, Cd²⁺, Hg²⁺ and Pb²⁺ cations caused an enhancement of anthryl fluorescence. Especially, the enhancement in case of the interaction of Hg²⁺ and Al³⁺ cations with the ligand was pronounced.     

Spectrophotometric study of complexation of dibenzopyridino-18-crown-6 with some transition and post-transition metal ions in DMSO solution using murexide as a metallochromic ligand

The complexation reaction of dibenzopyridino-18-crown-6 (DBPY 18C6) with Co²⁺, Cu²⁺, Zn²⁺, Pb²⁺, Cd²⁺, Hg²⁺, and Ag⁺ have been studied in DMSO at 25°C by the spectrophotometric method. Murexide was used as a competitive colored ligand. The stoichiometry of metal ion-murexide and metal ions with DBPY18C6 complexes were estimated by mole ratio and continuous variation methods and emphasized by the KINFIT program. The stoichiometry of all the complexes was found to be 1: 1 (metal ion/ligand). The order of stability constants for the obtained metal ion-murexide complexes (1: 1) varies in the order Cu²⁺ > Cd²⁺ > Co²⁺ ∼ Pb²⁺ > Zn²⁺ > Ag⁺ > Hg²⁺. This trend shows that the transition metal ions clearly obey the Irving-Williams role. For the post-transition metal ions, the ionic radius and soft-hard behavior was the major affects in varying of this order. The dibenzopyridino-18-crown-6 complexes with the used metal ions vary as Ag⁺ > Pb²⁺ > Cu²⁺ > Cd²⁺ > Hg²⁺ > Zn²⁺ > Co²⁺. The article is published in the original.     

Photoactive chemosensors 4: a Cu protein cavity mimicking fluorescent chemosensor for selective Cu recognition

Fluorescent chemosensor 3 can sense Cu²⁺ ions (1-8 μM) even in the presence of elevated levels of Ni²⁺, Cd²⁺, Zn²⁺, Hg²⁺, Ag⁺ and Pb²⁺ (5000 μM). 3 can also analyze for Ag⁺ ions (50-500 μM) in the presence of Ni²⁺, Cd²⁺, Zn²⁺, Hg²⁺ and Pb²⁺ (5000 μM) but Cu²⁺ strongly interferes.     

Metal Ions as Activators of Hypoxia Inducible Factor

Activation of antihypoxic program under the action of a number of transition and heavy metals has been studied using cell-based HIF1 ODD-luc and HRE-luc reporters. It has been demonstrated that Au³⁺, Pb²⁺, Sn²⁺, Hg²⁺ are weak HIF1 ODD-luc activators, likely reflecting their weak competition for the ironbinding site in the active center of HIF prolyl hydroxylase. Metals capable of replacing iron–Mn²⁺, Zn²⁺, Cu²⁺ и Ni²⁺–activate at high submillimolar concentrations, which indicates low permeability of the cell membrane for transition metals. The highest activation is observed for Co²⁺ and Cd²⁺, however, Cd²⁺ is highly toxic even at 10 μM, in contrast to Co²⁺, which activates both reporters without toxicity signs up to 25 μM for 24 h. A significant activation by Co²⁺ is observed already in low micromolar range of concentrations, which can be recommended for use in hypoxia mimicking.     

Quenching effect of some heavy metal ions on the fast peroxyoxalate-chemiluminescence of 1-(dansylamidopropyl)-1-aza-4,7,10-trithiacyclododecane as a novel fluorophore

The fast chemiluminescence (CL) arising from the reaction of bis(2,4,6-trichlorophenyl)oxalate (TCPO) with hydrogen peroxide in the presence of 1-(dansylamidopropyl)-1-aza-4,7,10-trithiacyclododecane (L) as a novel fluorophore, and imidazole as catalyst, has been studied in ethyl acetate solution. The relationships between the chemiluminescence intensity and concentrations of TCPO, imidazole, hydrogen peroxide and L are reported. In the presence of imidazole as catalyst, the entire CL signal was completed in less than 3 s. The quenching effect of Cu²⁺, Pb²⁺, Cd²⁺, Hg²⁺ and Ag⁺ ions on the chemiluminescent system was investigated, the resulting Stern–Volmer plots were obtained and the K_Q values were calculated. It was found that the quenching effect of metal ions on the chemiluminescence of L decreases in the order Cu²⁺ > Pb²⁺ > Cd²⁺ > Hg²⁺ > Ag⁺.     

Voltammetric Simultaneous Determination of Cu2+, Cd2+ and Pb2+ in Full Aqueous Medium Using Organic Nanoparticles of Disulfide Based Receptor

Disulfide based receptor was prepared using single step condensation reaction and suspended into organic nanoparticles to extend its practical application in aqueous samples. The prepared nanoparticles were used for the simultaneous recognition of three different metallic species (Cu²⁺, Cd²⁺, and Pb²⁺) in aqueous media through voltammetric studies. These metals can be determined simultaneously and without interferences from any of the other potential interferent metal ions, as different signals are displayed in cyclic as well as differential pulse voltammograms, with a detection limit of 193.0 nM for Cu²⁺, 52.0 nM for Cd²⁺ and 32.0 nM for Pb²⁺. The study was extended to real sample analysis by preparing the artificial mixtures of said metal ions.     

A chelating resin with bis[2-(2-benzothiazolylthioethyl)sulfoxide]: Synthesis, characterization and properties for the removal of trace heavy metal ion in water samples

A new chelating resin containing bis[2-(2-benzothiazolylthioethyl)sulfoxide] was synthesized using chloromethylated polystyrene as material and characterized by elemental analysis and infrared spectra. The adsorption capacities of the newly formed resin for Hg²⁺, Ag⁺, Cu²⁺, Zn²⁺, Pb²⁺, Mn²⁺, Ni²⁺, Cd²⁺ and Fe³⁺ were investigated over the pH range 1.0-6.0. The resin exhibited no affinity for alkali or alkaline earth metal ions. The maximum adsorption capacities of the resin for Hg²⁺, Ag⁺, Cu²⁺, Zn²⁺, Pb²⁺, Mn²⁺, Ni²⁺, Cd²⁺ and Fe³⁺ were 1.49, 0.96, 0.58, 0.11, 0.37, 0, 0.24, 0.36 and 0.25 mmol g⁻¹, respectively. In column operation it had been observed that Hg²⁺ and Ag⁺ in trace quantity could be separated from different binary mixtures and Hg²⁺ could be effectively removed from industrial wastewater and the natural water spiked with Hg²⁺ at usual pH.     

Preparation of o.o'-dichlorodithizone and a study of its metal complexing properties

o,o'-Dichlorodithizone was synthesised and its spectral characteristics were measured in carbon tetrachloride. The pH ranges for quantitative extraction of various metal complexes were determined. Values for wavelengths of maximum absorption and molar extinction coefficients are g'ven; the former increase in the order Ag⁺< Hg²⁺< Bi³⁺< Pb²⁺< Cd²⁺< Zn²⁺< Cu²⁺ and the latter in the order Ag⁺< Bi³⁺< Cu²⁺< Hg²⁺< Pb²⁺< Cd²⁺< Zn²⁺. Substitution of chlorine produces a regular bathochromic shift in wavelength of maximum absorption for reagent and their metal complexes compared to the dithizonates. No evidence was found that a ”steric effect“ of the o-substituent interferes with chelate ring formation for Zn, Cd, Hg and Pb; the results confirm, the view that complex formation takes place through the thio-H of the reagent. The extractability of lead as its o-dichlorodithizonate into carbon tetrachloride was investigated in the pH range 5–11 and the extraction constant was measured.     

A Simple Fluorometric Method Using Chlorophyll a for Determination of Hg2+ Ion

A simple and green analytical procedure based on chlorophyll a is presented for the determination of Hg²⁺ ion. Chlorophyll a was extracted and purified from the leaves of pea and is employed as a reagent for analysis of Hg²⁺ ion. It displays remarkable fluorescence emission at 674 nm when excited at 412 nm. The emission intensity decreased significantly on exposure to various concentrations of Hg²⁺ ion. This forms the basis for the determination of Hg²⁺ ion. The proposed method was evaluated for sensitivity and selectivity. The linear concentration range was found to be 2.0–10 μM with r² = 0.997 and the limit of detection for Hg²⁺ ion was 1.3 μM. Ions including Pb²⁺, Cd²⁺, Ag⁺, Zn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Mg²⁺, Mn²⁺, Ru³⁺, Er³⁺, K⁺, Na⁺, NH₄⁺, Cl⁻, NO₃⁻, CH₃COO⁻ and SO₄²⁻ did not interfere with the measurement of Hg²⁺ ion even at 500-fold excess. Since chlorophyll a is widely available in the leaves of most plants, and the extraction and purification process is simple, this technique can provide an alternative, sensitive and economical way to determine Hg²⁺ ion.     

Non-conductive nanomaterial enhanced electrochemical response in stripping voltammetry: The use of nanostructured magnesium silicate hollow spheres for heavy metal ions detection

Nanostructured magnesium silicate hollow spheres, one kind of non-conductive nanomaterials, were used in heavy metal ions (HMIs) detection with enhanced performance for the first time. The detailed study of the enhancing electrochemical response in stripping voltammetry for simultaneous detection of ultratrace Cd²⁺, Pb²⁺, Cu²⁺ and Hg²⁺ was described. Electrochemical properties of modified electrodes were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The operational parameters which have influence on the deposition and stripping of metal ions, such as supporting electrolytes, pH value, and deposition time were carefully studied. The anodic stripping voltammetric performance toward HMIs was evaluated using square wave anodic stripping voltammetry (SWASV) analysis. The detection limits achieved (0.186 nM, 0.247 nM, 0.169 nM and 0.375 nM for Cd²⁺, Pb²⁺, Cu²⁺ and Hg²⁺) are much lower than the guideline values in drinking water given by the World Health Organization (WHO). In addition, the interference and stability of the modified electrode were also investigated under the optimized conditions. An interesting phenomenon of mutual interference between different metal ions was observed. Most importantly, the sensitivity of Pb²⁺ increased in the presence of certain concentrations of other metal ions, such as Cd²⁺, Cu²⁺ and Hg²⁺ both individually and simultaneously. The proposed electrochemical sensing method is thus expected to open new opportunities to broaden the use of SWASV in analysis for detecting HMIs in the environment.     

Response surface methodology for optimization of heavy metal removal by magnetic biosorbent made from anaerobic sludge

In this study, optimum conditions for adsorption of heavy metals such as Cu²⁺, Cd²⁺ and Pb²⁺ onto a low-cost, magnetically modified-alkali conditioned anaerobically digested sludge (MADS) adsorbent were obtained. Response Surface Methodology (RSM) incorporating Central Composite Design (CCD) of experiments was applied to optimize four independent process variables. Statistical analysis was executed by ANOVA and the quadratic model developed had regression coefficients of 0.959, 0.957 and 0.95 for Cu²⁺, Cd²⁺ and Pb²⁺, respectively. The independent variables such as pH, time and initial concentration positively influenced adsorption capacity, q_e, whereas the value of q_e decreased with an increase in MADS dosage. Model validation experiments for optimization of adsorption process showed comparable results with predicted values. The adsorption capacity of MADS adsorbent at optimum conditions found through RSM analysis was 29.721 mg L^?1, 28.551 mg L^?1 and 28.601 mg L^?1 for Cu²⁺, Cd²⁺ and Pb²⁺ respectively.     

Bile acid based receptors for multiple metal ion recognition

A series of bile acid based receptors having triazole unit along with some additional heteroatom containing moieties as coordinating units for transition metal ion recognition has been synthesized. The UV–Vis studies revealed that these receptors show significant multiple binding affinity for Hg²⁺, Cd²⁺, Pb²⁺ and Cu²⁺ ions.     

Complexation of metal ions with the novel diazadithia crown ether carrying two anthryl pendants in acetonitrile–tetrahydrofuran

A new crown ether carrying two anthryl groups with nitrogen–sulfur donor atom was designed and synthesized by the reaction of the corresponding macrocyclic compound and 9-chloromethyl anthracene. The influence of metal cations such as Al³⁺, Zn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Mn²⁺, Cu²⁺, Cd²⁺, Hg²⁺ and Pb²⁺ on the spectroscopic properties of the ligand was investigated in acetonitrile–tetrahydofuran solution (1/1) by means of absorption and emission spectrometry. Absorption spectra show isosbestic points in the spectrophotometric titration of Fe²⁺, Fe³⁺, Al³⁺, Cu²⁺ and Hg²⁺. The results of spectrophotometric titration experiments disclosed the complexation stoichiometry and complex stability constant of the novel ligand with Fe²⁺, Fe³⁺, Al³⁺, Cu²⁺and Hg²⁺cations. The presence of excess amounts of Al³⁺, Zn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Mn²⁺, Cu²⁺, Cd²⁺, Hg²⁺ and Pb²⁺ cations caused an enhancement of anthryl fluorescence. The ligand showed good sensitivity for Zn²⁺ with respect to other metal cations with linear range and detection limit of 1.4 × 10^?7 to 4.1 × 10^?6 M and 1.0 × 10^?8 M respectively.