Synthesis and metal ion complexation of acyclic Schiff base podands with lipophilic amide and ester end groups

A series of acyclic Schiff base podands 14?C19 with lipophilic amide and ester end groups were synthesized in good yield and in a simple way. Their transition metal ions complexation was studied using conductometric method in acetonitrile (AN) at 25 °C. Schiff base podands 14?C16 showed a continuous decrease in the molar conductances in their complexation with Hg²⁺, Pb²⁺, Cu²⁺, Zn²⁺ and Cd²⁺ which begins to level off at a mole ratio of 1:1 crown-to-metal indicating the formation of a stable 1:1 complexes. The order of the stability constants of the metal ions studied with the Schiff base podands 14, 15 and 16 is: Hg²⁺ > Pb²⁺ > Cu²⁺ > Zn²⁺ > Cd²⁺ > Ag⁺. Metal ion complexation by acyclic diamide or diester podands involves presumably the oxygen atoms of the carbonyl groups in addition to the nitrogen atoms of the imino groups.     

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.     

Formation and Stability of Binary Complexes of Divalent Ecotoxic Ions (Ni, Cu, Zn, Cd, Pb) with Biodegradable Aminopolycarboxylate Chelants (dl-2-(2-Carboxymethyl)Nitrilotriacetic Acid, GLDA, and 3-Hydroxy-2,2′-Iminodisuccinic Acid, HIDS) in Aqueous Solutions

The protonation and complex formation equilibria of two biodegradable aminopolycarboxylate chelants {dl-2-(2-carboxymethyl)nitrilotriacetic acid (GLDA) and 3-hydroxy-2,2??-iminodisuccinic acid (HIDS)} with Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺ and Pb²⁺ ions were investigated using the potentiometric method at a constant ionic strength of I?=?0.10?mol·dm^?3 (KCl) in aqueous solutions at 25?±?0.1?°C. The stability constants of the proton?Cchelant and metal?Cchelant species for each metal ion were determined, and the concentration distributions of various complex species in solution were evaluated for each ion. The stability constants (log₁₀ K _ML) of the complexes containing Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺ and Pb²⁺ ions followed the identical order of log₁₀ K _CuL?>?log₁₀ K _NiL?>?log₁₀ K _PbL?>?log₁₀ K _ZnL?>?log₁₀ K _CdL for either GLDA (13.03?>?12.74?>?11.60?>?11.52?>?10.31) or HIDS (12.63?>?11.30?>?10.21?>?9.76?>?7.58). In each case, the constants obtained for metal?CGLDA complexes were larger than the corresponding constants for metal?CHIDS complexes. The conditional stability constants (log₁₀ $ K_{\text{ML}}^{'} $ ) of the metal?Cchelant complexes containing GLDA and HIDS were calculated in terms of pH, and compared with the stability constants for EDTA and other biodegradable chelants.     

Competitive heavy metal removal by poly(2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid‐co‐itaconic acid)

The competitive removal of Pb²⁺, Cu²⁺, and Cd²⁺ ions from aqueous solutions by the copolymer of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS) and itaconic acid (IA), P(AMPS‐co‐IA), was investigated. Homopolymer of AMPS (PAMPS) was also used to remove these ions from their aqueous solution. In the preparation of AMPS–IA copolymer, the molar percentages of AMPS and IA were 80 and 20, respectively. In order to observe the changes in the structures of polymers due to metal adsorption, FTIR spectra by attenuated total reflectancetechnique and scanning electron microscopy (SEM) pictures of the polymers were taken both before and after adsorption experiments. Total metal ion removal capacities of PAMPS and P(AMPS‐co‐IA) were 1.685 and 1.722 mmol Me²⁺/g_polymer, respectively. Experimental data were evaluated to determine the kinetic characteristics of the adsorption process. Competitive adsorption of Pb²⁺, Cu²⁺, and Cd²⁺ ions onto both PAMPS and P(AMPS‐co‐IA) was found to fit pseudo‐second‐order type kinetics. In addition, the removal orders in the competitive adsorption of these metal ions onto PAMPS and P(AMPS‐co‐IA) were found to be Cd²⁺ > Pb²⁺ > Cu²⁺ and Pb²⁺ > Cd²⁺ > Cu²⁺, respectively. Copyright © 2008 John Wiley & Sons, Ltd.     

Complexation and thermodynamic studies of oxathiadibenzocrown ethers with Cu2+, Pb2+, Zn2+ and Cd2+ ions

A thermodynamic study of the complexation of Cu²⁺, Pb²⁺, Zn²⁺ and Cd²⁺ ions with 1 and 2 in acetonitrile has been carried out. The study was conducted in the temperature range 283–308 K using a conductometric technique. The observed molar conductivity, Λ, was found to decrease significantly for mole ratios [L]_t/[M]_t less than unity in all cases. A model involving 1:1 stoichiometry has been used to analyze the conductivity data. The stability constant, K, for each 1:1 complex was determined from the conductivity data by using a nonlinear least-squares curve fitting procedure. The results show that compound 1 has no peak selectivity for any of the metal cations, while compound 2 selectively associates with Cu²⁺ and Pb²⁺. Complexes of 1 have the following stability order Pb²⁺ > Cu²⁺ > Zn²⁺ > Cd²⁺  and Pb²⁺ > Cu²⁺ for the complexes of 2. The ?H° and ?S° values for the complexation process were obtained from the slope and intercept of the Van’t Hoff plots respectively. All ?G° values were negative and were determined from the Gibbs–Helmholtz equation and the significance of these values is discussed.     

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⁺.     

Nanometer-sized alumina coated with chromotropic acid as solid phase metal extractant from environmental samples and determination by inductively coupled plasma atomic emission spectrometry

A method for solid phase extraction of trace metals such as Cd²⁺, Cr⁶⁺, Cu²⁺, Fe³⁺, Mn²⁺, Ni²⁺, Pb²⁺ and Zn²⁺ using nanometer-sized alumina coated with chromotropic acid prior to determination by inductively coupled plasma atomic emission spectrometry (ICP-AES) has been developed. Various influencing parameters on the separation and preconcentration of trace metals, pH, flow rate, sample volume, amount of adsorbent, concentration of eluent and sorption kinetics have been studied. The detection limits for Cd²⁺, Cr⁶⁺, Cu²⁺, Fe³⁺, Mn²⁺, Ni²⁺, Pb²⁺ and Zn²⁺ were found to be 0.14, 0.62, 0.22, 0.54, 0.27, 0.28, 0.53 and 0.38 ng ml^− 1, respectively. The adsorption capacity of the solid phase adsorption material is 10.3, 11.3, 14.5, 16.4, 15.1, 11.7, 15.4 and 16.8 mg g^− 1 for Cd²⁺, Cr⁶⁺, Cu²⁺, Fe³⁺, Mn²⁺, Ni^2+, Pb²⁺ and Zn²⁺, respectively. The preconcentration factor was obtained in the range of 50-100 for all studied metal ions. Coexisting ions over a high concentration range have not shown any significant effects on the determination of aforesaid metal ions. The accuracy of the proposed method was tested by standard reference materials (NIST 1643e: water, NIST 1573a: tomato leaves and NIST 1568a rice flour) and natural waters and the results obtained were in good agreement with the certified values.     

Anthroneamine based chromofluorogenic probes for Hg2+ detection in aqueous solution

Anthroneamine derivatives 1–3 (H₂O:DMSO; 9:1, HEPES buffer, pH 7.0 ± 0.1) undergo highly selective fluorescence quenching with Hg²⁺. The observed linear fluorescence intensity change allows the quantitative detection of Hg²⁺ between 200 nM/40 ppb—12 μM/2.4 ppm even in the presence of interfering metal ions viz. Na⁺, K⁺, Mg²⁺, Ca²⁺, Ba²⁺, Cr³⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Ag⁺, Cd²⁺, Pb²⁺. Probes 1–3 and their Hg²⁺ complexes also show the broad pH resistance for their practical applicability.     

A highly selective colorimetric sensor for Hg2+ based on a copper (II) complex of thiosemicarbazone in aqueous solutions

By applying an indirect strategy, a new copper (Ⅱ) complex of a thiosemicarbazone L has been successfully developed as a colorimetric chemosensor for the sensitive detection of mercury (Ⅱ) ions. In the presence of copper (Ⅱ) ions, the colorless solution of L became yellow; however, upon the addition of traces of mercury (Ⅱ) ions, the yellow color faded to colorless immediately. Other ions, including Fe3+ , Ag+ , Ca2+ , Zn2+ , Pb2+ , Cd2+ , Ni2+ , Co2+ , Cr3+ and Mg2+ had a negligible influence on the probe behavior. The detection limits were 5.0×10 -6 M and 3.0×10 -7 M of Hg2+ using the visual color changes and UV-vis changes respectively. Test strips based on Cu-L were fabricated, which could act as a convenient and efficient Hg2+ test kits.     

Synthesis,characterization and applications of schiff base chemosensor for determination of Cu2+ ions

A novel thiazole-based Schiffbase chemosensor SB1 with N- and O- donor atoms was synthesized and characterized by different techniques (UV–vis, ¹³C NMR, ¹H NMR, and FT-IR analysis). The chemosensor SB1 was used for the determination of Cu²⁺ ions in various samples. The significant spectral changes in absorption spectra of chemosensor SB1 at 220 and 416 nm and the color change from light yellow to yellowish-brown indicate high selectivity and sensitivity towards Cu²⁺ ions as compared to other cations (Na⁺, K⁺, Ag⁺, Zn²⁺, Ni²⁺, Pb²⁺, Mn²⁺, Mg²⁺, Co²⁺, Cd²⁺, Sn²⁺, Hg²⁺, Cr³⁺, Fe^3+, and Al³⁺). The sensing mechanism of SB1 was investigated through various techniques such as FT-IR, UV–vis and ¹H NMR titration experiment and further confirmed by DFT computational studies. The 2:1 binding mode between SB1 and Cu²⁺ ions was confirmed by Job‘s plot using UV–vis spectrophotometry. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.015 and 0.0471 µg mL^?1, respectively. The percent recovery of Cu²⁺ from various environmental samples was found to be 95.00–103.33% at various levels. These obtained results demonstrate that chemosensor SB1 is a cost-effective, facile, selective, sensitive, and colorimetric sensing platform to detect trace amounts of Cu²⁺ ions in variousenvironmental and agricultural samples.     

Silver nanoparticle loaded on activated carbon and activated carbon modified with 2-(4-isopropylbenzylideneamino)thiophenol (IPBATP) as new sorbents for trace metal ions enrichment

The efficiencies and performances of silver nanoparticle loaded activated carbon modified with 2-(4-isopropylbenzylideneamino)thiophenol (IPBATP-Ag-NP-AC) and activated carbon modified with IPBATP (IPBATP-AC), as new sorbents, were evaluated for separation and preconcentration of Cu²⁺, Zn²⁺, Co²⁺, Cd²⁺ and Pb²⁺ ions from real environmental samples. The retained metals content was reversibly eluted using 5?mL of CH₃COOH (6.0?mol?L^?1) and/or 10?mL of 4.0?mol?L^?1 HNO₃ for IPBATP-Ag-NP-AC and IPBATP-AC, respectively. The experimental parameters influence the recoveries of metal ions including pH, amounts of ligand and supports, condition of eluents, sample and eluent flow rates of has been investigated. The preconcentration factors were found to be 100 for Zn²⁺, Cd²⁺, Co²⁺, Cu²⁺ and 50 for Pb²⁺ ions using IPBATP-Ag-NP-AC, and 50 for Zn²⁺, Cd²⁺, Co²⁺, Cu²⁺ and 25 for Pb²⁺ ions using IPBATP-AC. The detection limit of both SPE-based sorbents was between 1.6–2.5?ng?mL^?1 for IPBATP-AC and 1.3–2.5?ng?mL^?1 for IPBATP-Ag-NP-AC. The proposed methods have been successfully applied for the extraction and determination of the understudy metal ions content in some real samples with extraction efficiencies higher than 90% and relative standard deviations (RSD) lower than 2.4%.     

Synthesis of a new pyrene-devived fluorescent probe for the detection of Zn2+

A novel pyrene-based receptor bearing benzothiazole was synthesized as a good turn-on fluorescent sensor for the recognition of Zn²⁺. The probe showed an excellent selectivity for Zn²⁺over most other competing ions (eg, Cr³⁺, Li⁺, Cd²⁺, Al³⁺, Pb²⁺, Li⁺, Mg²⁺, Ag⁺, Ca²⁺, Ni²⁺, Mn²⁺, Fe³⁺, Hg²⁺, Ba²⁺, K⁺, Na⁺, Cu²⁺, Fe²⁺) in EtOH-HEPES (65:35, v/v, pH?=?7.20), which might be attributed to the photoinduced electron transfer (PET) mechanism. The formation of 1:1 stoichiometric PBZ-Zn²⁺ complex was determined based on the Job's plot, ¹H NMR titration and ESI-MS. The binding constant of the complex was 4.04?×?10⁴?M^?1 with a detection limit of 2.58?×?10^?7?M. The potential application of the PBZ in real water samples for recognizing Zn²⁺ was investigated. Bio-imaging study also revealed that PBZ could be applied to detecting Zn²⁺ in live cells. These results indicated that PBZ could be a favorable probe for Zn²⁺.     

Heavy metal-induced inhibition of Aspergillus niger nitrate reductase: applications for rapid contaminant detection in aqueous samples

Enzyme inhibition assays have the potential to rapidly screen and identify heavy metals in environmental samples. Inhibition of nitrate reductase (NR) was examined as a method for detecting toxic metals. The activity of NR (EC 1.6.6.2) from Aspergillus niger was assayed as a function of metal concentration in the presence of Cd²⁺, Cr³⁺, Cr⁶⁺, Cu²⁺, Ni²⁺, Pb²⁺, and Zn²⁺. NR exhibited sensitivity to these metals at concentrations below 10 μM. Various buffers were screened for their ability to protect NR activity from metal inhibition, and 3-(N-morpholino) propanesulfonic acid (MOPS) was selected as the buffering system for the NR assays as it exhibited the least interference with metal inhibition, thus providing increased assay sensitivity. The hypothesis that chelating agents could prevent the inhibition of NR activity by metal ions was also tested. Results indicated that 10 mM ethylenediaminetetraacetic acid (EDTA) could protect NR activity from inhibition by Cr³⁺, Cu²⁺, Cd²⁺, Ni²⁺, and Zn²⁺ at concentrations below 100 μM, but that the EDTA had no effect on NR inhibition by Cr⁶⁺. An amount of 10 mM nitrilotriacetic acid (NTA) prevented NR inhibition by Cd²⁺, Cu²⁺, Ni²⁺, Pb²⁺, and Zn²⁺ at metal concentrations below 100 μM. However, 10 mM NTA was unable to protect the enzyme from inhibition by either Cr³⁺ or Cr⁶⁺. These results indicated that through specific metal chelation, a NR-based method for individually quantifying Cr³⁺ and Cr⁶⁺ species in aqueous solutions could be developed. The ability to restore activity to NR which been previously inhibited by exposure to 100 μM Pb²⁺, Cd²⁺, Zn²⁺, Cu²⁺, and Cr³⁺ was explored to determine whether NR activity could be recovered by EDTA additions for use in consecutive metal inhibition assays. The results showed NR activity could not be regained after exposure to Cr³⁺ or Cu²⁺, but did partially recover activity after Cd²⁺, Pb²⁺, and Zn²⁺ exposure.     

Dual-mode recognition of transition metal ions by bis-triazoles chained pyrenes

Fluorescent chemosensors 7−10, with variable methylene chain length as spacers between the two triazole methyl ether units, have been synthesized under ‘Click’ condition, where the bistriazoles are used as the metal ion binding sites and the pyrenes as the fluorophores. Compound 10, having the longest methylene chain among 7−10, shows monomer and excimer fluorescence quenching in acetonitrile toward Ni²⁺, Pb²⁺, Cu²⁺, Hg²⁺, and Cr³⁺ ions, however, it shows an enhanced monomer but a decreased excimer emission when complexed with Cd²⁺ and Zn²⁺ ions.     

In-situ electrochemical and piezogravimetric studies on the application of macrocyclic resorcinarene tetramer in the development of chemically-modified heavy metals ions detection platform in aqueous media

The new application of C-dec-9-enylcalix[4]resorcinarene (R₁), as an ionophore to detect heavy metals (HMs) cations (Cd²⁺, Hg²⁺, Cu²⁺, and Pb²⁺) in the aqueous media has been investigated through the preparation of an effective mass-sensitive sensor via the exploitation of a flow-type QCM-I technique. By adjusting the ions’ amounts in model solutions over a wide range of concentrations, acquired changes in the oscillating frequency related to the loading of metal ions on the sensor’s surface were gained, and thus favorable metrological parameters displaying the lowest detection limit (LOD) associated with copper ions (10 ppb). Simultaneously, a novel voltammetric sensor was prepared by modifying gold screen-printed electrodes (SPEs) with R₁. Electrochemical characterization employing CV, SWV, and EIS was carried out, showing the success of the electrode modification. Then, the experimental conditions of supporting electrolyte, pH, accumulation time, and accumulation potential were optimized to achieve an enhanced detection. The R₁@SPE sensor simultaneously detected the HMs (Cd²⁺, Hg²⁺, Cu²⁺, Pb²⁺), and the lowest LOD was associated with Pb²⁺ (0.19 ppb). The selectivity evaluation of the electrochemical sensor was performed by studying the effect of interferences majorly present in water sources (Mg²⁺, Ni²⁺, Zn²⁺, Al³⁺, and K⁺) on the SWV detection signals, and it was revealed that the interfering ions did not affect the simultaneous detection of the studied HMs (RSD less than 5%), the voltammetric sensors also presented excellent repeatability and reproducibility (RSD less than 5%).     

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.     

Selective removal of Cd(II), As(III), Pb(II) and Cr(III) ions from water resources using novel 2-anthracene ammonium-based magnetic ionic liquids

Facile synthesis of two 2-anthracene ammonium-based magnetic ionic liquids (MILs), 2-anthracene ammonium tetrachloroferrate (III) ([2A-A]FeCl₄) and 2-anthracene ammonium trichlorocobaltate (II) ([2A-A]CoCl₃) was performed by protonation of 2-aminoanthracene, followed complexation with FeCl₃/CoCl₂. The MILs were tested in the adsorptive removal of Cd²⁺, As³⁺, Pb²⁺ and Cr³⁺ from water sources. Upon treatment with 10 mg dosage of MILs in 10 mL aqueous solution of 50 ppm each of Cd²⁺, As³⁺, Pb²⁺ and Cr³⁺, adsorption capacity (mg/g) in the range of 5.73–55.5 and 23.6–56.8 for [2A-A]FeCl₄ and [2A-A]CoCl₃ respectively were recorded. Thus, the optimization, kinetic and isotherms studies were conducted using the [2A-A]CoCl₃ adsorbent. The [2A-A]CoCl₃ was more effective in pH 7–9, and equilibrium adsorption was achieved after 60 min contact time. The adsorption process proceeded via the Pseudo-second order pathway and the Langmuir isotherm model is the best fit for the adsorption process (with q_max = 227 – 357 mg/g) of all the targeted metal ions. The [2A-A]CoCl₃ adsorbent demonstrated practicality with large distribution and selectivity coefficients of the targeted ions, and up to six times regeneration.     

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.     

Using Zeolite/Polyvinyl alcohol/sodium alginate nanocomposite beads for removal of some heavy metals from wastewater

Functionalized Polyvinyl alcohol/sodium alginate (PVA/SA) beads were synthesized via blending Polyvinyl alcohol (PVA) with sodium alginate (SA) and the glutaraldehyde was used as a cross-linking agent. The zeolite nanoparticles (Zeo NPs) incorporated PVA/SA resulting Zeo/PVA/SA nanocomposite (NC) beads were synthesized for removal of some heavy metal from wastewater. The synthesizes beads were characterized via Fourier transforms infrared spectroscopy (FTIR), X-ray diffraction (XRD), particle size analyzer (PSA), and scanning electron microscope (SEM). The adsorption kinetics of the selected metal ions onto Zeo/PVA/SA NC beads followed the pseudo-first-order model (PFO) and the adsorption isotherm model was well fitted by the Langmuir model. Moreover, the thermodynamic studies were also examined; the outcomes showed that the adsorption mechanisms of the selective metal ions were endothermic, the chemical in nature, spontaneous adsorption on the surface of the Zeo/PVA/SA NC beads. The removal efficiency using Zeo/PVA/SA NC modified beads reached maximum at the pH value of 6.0 for Pb²⁺, Cd²⁺, Sr²⁺, Cu²⁺, Zn²⁺, Ni²⁺, Mn²⁺ and Li²⁺ with 99.5, 99.2, 98.8, 97.2, 95.6, 93.1, 92.4 and 74.5%, respectively, while the highest removal are achieved at pH = 5 for Fe³⁺ and Al³⁺ with 96.5 and 94.9%, respectively and decreased at lower or higher pH values. The survival count (%) of the E. coli cells were 34% on the SA beads, 11% on the PVA/SA, and 1% on the Zeo/PVA/SA NC modified beads, after 120 min exposure at 25 °C. Reusability experimental displays that the synthesized beads preserved a significant decrease in the sorption capacity after 10 repeating cycles. The Zeo/PVA/SA NC beads were able to eliminate 60–99.8% of Al³⁺, Fe³⁺, Cr³⁺, Co²⁺, Cd²⁺, Zn²⁺, Mn²⁺, Ni²⁺, Cu²⁺, Li²⁺, Sr²⁺, Si²⁺, V²⁺, and Pb²⁺ ions from the natural wastewater samples collected from 10th Ramadan City, Cairo, Egypt.     

Spectrophotometric Study of Complexation of Tri-Aza Dibenzosulfide and Dibenzosulfoxide Macrocyclic Compounds with Heavy Metal Ions

The complexation reactions between 7,10,13-triaza-1-thia-4,16-dioxa-20,24-dimethyl-2,3;17,18-dibenzo-cyclooctadecane-6,14-dione ( TTD ) and 7,10,13-triaza-1-sulfoxo-4,16-dioxa-20,24-dimethyl-2,3;17,18-dibenzo-cyclooctadecane-6,14-dione ( TSD ) macrocycles with Ag⁺, Cd²⁺, Cu²⁺, Pb²⁺, Sr²⁺, Tl⁺, and Zn²⁺ ions have been studied in ethanol and methanol solutions at 25°C. The complexes formed between macrocycles ( TTD ) and ( TSD ) with these metals cations had a stiochiometry of 1:1 and 1:2, respectively. The stability constants of the resulting complexes were determined and found to decrease in the order Cu²⁺ > Zn²⁺ > Ag⁺ > Tl⁺ > Cd²⁺ > Pb²⁺ > Sr²⁺ with macrocycle ( TTD ) and Tl⁺ > Zn²⁺ > Cd²⁺ > Pb²⁺ > Cu²⁺ > Ag⁺ > Sr²⁺ with macrocycle ( TSD ).