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.     

The removal of heavy metal cations by natural zeolites

In this study, the adsorption behavior of natural (clinoptilolite) zeolites with respect to Co²⁺, Cu²⁺, Zn²⁺, and Mn²⁺ has been studied in order to consider its application to purity metal finishing wastewaters. The batch method has been employed, using metal concentrations in solution ranging from 100 to 400 mg/l. The percentage adsorption and distribution coefficients (K_d) were determined for the adsorption system as a function of sorbate concentration. In the ion exchange evaluation part of the study, it is determined that in every concentration range, adsorption ratios of clinoptilolite metal cations match to Langmuir, Freundlich, and Dubinin–Kaganer–Radushkevich (DKR) adsorption isotherm data, adding to that every cation exchange capacity metals has been calculated. It was found that the adsorption phenomena depend on charge density and hydrated ion diameter. According to the equilibrium studies, the selectivity sequence can be given as Co²⁺ > Cu²⁺ > Zn²⁺ > Mn²⁺. These results show that natural zeolites hold great potential to remove cationic heavy metal species from industrial wastewater.     

Kinetics of the exchange between MnO or Mn3O4 and some divalent cations in aqueous solution

The kinetics of the exchange between MnO or Mn₃O₄ and Co²⁺, Cu²⁺, Ni²⁺, or Zn²⁺ ions in solution, was determined by measuring the γ-activity of⁵⁶Mn acquired by the solution after shaking with the neutron irradiated solid. The results indicated a fast exchange followed by a slower apparently diffusion-controlled exchange. The exchange capacity increased in the series: Co²⁺<Ni²⁺<Cu²⁺=Zn²⁺ for MnO and Ni²⁺<Co²⁺<Zn²⁺<Cu²⁺ for Mn₃O₄. The trends could not be satisfactorily explained by the ionic radii or crystal field stabilisation-energies. In the case of MnO, the results were discussed in terms of the estimated standard enthalpy change of the exchange reaction.     

Biosorption of Heavy Metal Ions (Cu2+, Mn2+, Zn2+, and Fe3+) from Aqueous Solutions Using Activated Sludge: Comparison of Aerobic Activated Sludge with Anaerobic Activated Sludge

The potential of using two different kinds of air drying of activated sludge (aerobic activated sludge and anaerobic activated sludge) for the removal of Cu²⁺, Mn²⁺, Zn²⁺, and Fe³⁺ from aqueous solutions was assessed. Results indicated that the maximum biosorption occurred at pH?=?5.0 for Cu²⁺, Zn²⁺, and Mn²⁺ and pH?=?3.0 for Fe³⁺. The kinetic parameters of biosorption data were found to be best fitted to the second-order equation. Also, it was found that the best dosage for biosorption was 0.2?g for both aerobic activated sludge and anaerobic activated sludge. The experimental results were fitted well to the Langmuir, Freundlich, and Dubinin?CRadushkevich (D-R) isotherms. The maximum biosorption capacities of Cu²⁺, Mn²⁺, Zn²⁺, and Fe³⁺ for aerobic activated sludge were 65.789, 44.843, 64.935, and 75.756?mg/g, respectively, while they were 59.880, 49.020, 62.500, and 69.444?mg/g for anaerobic activated sludge, respectively. The mean free energy values evaluated from the D-R model indicated that the biosorptions of studied heavy metal ions onto activated sludge were taken place by chemical interaction. The results of this study provided valuable information on the biosorption of heavy metals by activated sludge that may contribute in wastewater treatment.     

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.     

A radiochemical study of the kinetics of exchange between manganese oxides and some cations in solution

The kinetics of the exchange between⁵⁶Mn-labelled manganese dioxide and cations in aqueous solution was studied by measuring the β⁻ activity acquired by the solution. The results of the exchange between a chemical γ MnO₂ and a divalent M²⁺ ion (M=Mn, Co, Cu or Zn) or a trivalent M³⁺ ion (M=Ga, Fe, In, Rh or Al) indicate a fast initial process followed by a diffusion—controlled exchange. It is assumed that M²⁺ ions exchange with Mn²⁺ ions and M³⁺ ions exchange with Mn³⁺ ions in MnO₂. The process depends on the radii of the host and substituent ions and on consideration of crystal field stabilisation energies. It seems that the γ MnO₂ studied contains more Mn³⁺ than Mn²⁺ ions. The possibility of the exchange between Mn ions and cations of a different charge cannot be ruled out. The exchange between Co²⁺ ions and MnO₂ was enhanced in presence of pyrophosphate, which stabilises Mn(III) as a complex. The fraction of Mn in different samples of MnO₂ exchanged with a given cation depends on the type and not on the surface area of the sample.     

Hydrothermal development of magnetic-hydrochar nanocomposite from pineapple leaves and its performance as an adsorbent for the uptake of Mn2+ and reuse of the metal loaded adsorbent in latent fingerprint

Manganese is one of the heavy metals that is a major environmental concern when present in large amount. Manganese is discarded into water systems by numerous industries, including mining, batteries and electroplating etc. Pineapple leaves were applied as a biomass source to produce a magnetic hydrothermal treated hydochar nanocomposite; Fe₃O₄-HC. The BET surface area of Fe₂O₃-HC nanocomposite was 21.27 m²/g. Batch adsorption experiments revealed that the uptake of Mn²⁺ fit well in the pseudo second kinetics model, while the adsorption isotherm best fit the Freundlich model, with a maximum adsorption capacity of 2.99 mg/g at 25 °C and a pH of 5. The obtained thermodynamic parameters demonstrated that Mn²⁺ ion adsorption using the Fe₂O₃-HC nanocomposite was endothermic and nonspontaneous. Additionally, Fe₂O₃-HC nanocomposite demonstrated to be highly selective towards Mn²⁺ ions in the presence of other ions. The removal percentage of Mn²⁺ from a real water sample spiked with 50 mg/L Mn²⁺ was reported to be 53.2%. The spent adsorbent was then used to detect latent fingerprints, which revealed that Mn²⁺-Fe₂O₃-HC nanocomposite generated better and clear latent fingerprints than Fe₂O₃-HC nanocomposite.     

Chelation ion-exchange properties of salicylic acid-urea-formaldehyde copolymers

Chelation ion-exchange properties of copolymers prepared from salicylic acid, urea and formaldehyde by condensation in presence of acid catalyst were studied for Cu²⁺, Fe³⁺, UO²⁺, Mn²⁺,Zn²⁺ and Co²⁺ ions. A batch equilibration method was adopted to study the selectivity of metal ion uptake. This method involved the measurement of distribution of a given metal between the copolymer sample and a solution containing the metal ions. The study was carried out over a wide pH range and in media of various ionic strengths. The copolymer showed a higher selectivity for UO₂ ²⁺, Cu²⁺ and Fe³⁺ ions than Mn²⁺, Co²⁺ and Zn²⁺ ions.     

Biochemical and enzymatic properties of a novel marine fibrinolytic enzyme from <Emphasis Type="Italic">Urechis unicinctus</Emphasis>

A novel potent protease, Urechis unicinctus fibrinolytic enzyme (UFE), was first discovered by our laboratory. In this study, we further investigated the enzymatic properties and dynamic parameters of UFE. As a low molecular weight protein, UFE appeared to be very stable to heat and pH. When the temperature was <50°C, the remnant enzyme activity remained almost unchanged, but when the temperature was raised to 60#x00B0;C the remnant enzyme activity began to decrease rapidly. UFE was quite stable in a pH range of 3.0–12.0, especially at slightly alkaline pH values. Mn²⁺, Cu²⁺, and Fe²⁺ ions were activators of UFE, whereas Fe³⁺ and Ag⁺ ions were inhibitors. Fe²⁺ ion along with Fe³⁺ ion might regulate UFE activity in vivo. The optimum pH and temperature of UFE were about 8.0 and 50°C, respectively. When using casein as substrate and a substrate concentration <0.1% casein (w/v), the reaction velocity was increased with substrate concentration. Also when using casein as substrate, the determined K _m and V _max of UFE were 0.5298 mg/mL and 3.0845 mol of l-tyrosine equivalent, respectively. Our systematic research results are significant when UFE is applied for medical and industrial purposes.     

An Oxidant- and Organic Solvent-Resistant Alkaline Metalloprotease from Streptomyces olivochromogenes

Organic solvent- and detergent-resistant proteases are important from an industrial viewpoint. However, they have been less frequently reported and only few of them are from actinomycetes. A metalloprotease from Streptomyces olivochromogenes (SOMP) was purified by ion exchange with Poros HQ and gel filtration with Sepharose CL-6B. Apparent molecular mass of the enzyme was estimated to be 51 kDa by sodium dodecyl sulfate–polyacrylamide gel electrophoresis and gelatin zymography. The activity was optimum at pH 7.5 and 50 °C and stable between pH 7.0 and 10.0. SOMP was stable below 45 °C and Ca²⁺ increased its thermostability. Ca²⁺ enhanced while Co²⁺, Cu²⁺, Zn²⁺, Mn²⁺, and Fe²⁺ inhibited the activity. Ethylenediaminetetraacetic acid and ethylene glycol-bis (β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid, but not phenylmethylsulfonyl fluoride, aprotinin, and pefabloc SC, significantly suppressed the activity, suggesting that it might be a metalloprotease. Importantly, it is highly resistant against various detergents, organic solvents, and oxidizing agents, and the activity is enhanced by H₂O₂. The enzyme could be a novel protease based on its origin and peculiar biochemical properties. It may be useful in biotechnological applications especially for organic solvent-based enzymatic synthesis.     

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.     

Thermal Decomposition of Chloromethylated Poly(styrene)-PAN Resin and Its Complexes with Some Transition Metal Ions

The complexes formed by the chemically modified chloromethylated poly(styrene)-PAN (CMPS-PAN) as a resin chelating ion exchanger were characterized by infrared and potentiometry. The thermal degradation of pure CMPS-PAN resin and its complexes with Au³⁺, Cr³⁺, Cu²⁺, Fe³⁺, Mn²⁺ and Pt⁴⁺ in air atmosphere has been studied using thermal gravimetry (TG) and derivative thermal gravimetry (DTG). The results showed that four different steps accompany the decomposition of CMPS-PAN resin and its complexes with the metal ions. These stages were affected by the presence of the investigated metal ions. The thermal degradation of CMPS-PAN resin in the presence of the ions showed different stability of the resin in the following decreasing order: Au³⁺>Pt⁴⁺>Mn²⁺>Cu²⁺>Cr³⁺>Fe³⁺. On the basis of the applicability of a non-isothermal kinetic equation, the decomposition process was a first-order reaction. The activation energy, Ea, the entropy change, ΔS ^*, the enthalpy change, ΔH ^* and the Gibbs free energy of activation, ΔG ^* were calculated by applying the theory of the reaction rates. The effect of the different central metal ions on the calculated thermodynamic activation parameters was discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

An optical chemical sensor for mercury ion based on 2-mercaptopyrimidine in PVC membrane

An optical chemical sensor based on 2-mercaptopyrimidine (2-MP) in plasticized poly(vinyl chloride) (PVC) membrane incorporating (N,N-diethyl-5-(octadecanoylimino)-5H benzo[a]phenoxazine-9-amine (ETH 5294) and sodium tetraphenyl borate (NaTPB) for batch and flow-through determination of mercury ion is described. The response of the sensor is based on selective complexation of Hg²⁺ with 2-MP in the membrane phase, resulting in an ion exchange process between H⁺ in the membrane and Hg²⁺ in the sample solution. The influences of several experimental parameters, such as membrane composition, pH, and type and concentration of the regenerating reagent, were investigated. The sensor has a response range of 2.0 × 10⁻⁹ to 2.0 × 10⁻⁵ mol L⁻¹ Hg²⁺ with a detection limit of 4.0 × 10⁻¹⁰ mol L⁻¹ and a response time of ≤45 s at optimum pH of 6.5 with high measurement repeatability and sensor-to-sensor reproducibility. It shows high selectivity for Hg²⁺ over several transition metal ions, including Ag⁺, Cd²⁺, Co²⁺, Cr³⁺, Cu²⁺, Fe³⁺, Mn²⁺, Ni²⁺, and common alkali and alkaline earth ions such as Na⁺, K⁺, Mg²⁺, Ca²⁺, and Pb²⁺. The sensor membrane can be easily regenerated with dilute acid solutions. The sensor has been used for the determination of mercury ion concentration in water samples.     

Task-specific ionic liquid trioctylmethylammonium salicylate as extraction solvent for transition metal ions

A quaternary ammonium-based room temperature ionic liquid trioctylmethylammonium salicylate (TOMAS) has been studied as an extractant of transition metal ions (Fe³⁺, Cu²⁺, Ni²⁺, Mn²⁺) in aqueous solutions. The effect of pH value on the recovery of metal ions has been investigated. The mechanism of extraction into the ionic liquid has been proposed. The possibility of stripping voltammetric determination of transition metals in aqueous solutions using TOMAS-modified electrodes has been demonstrated.     

Synthesis and characterization of poly(4-vinyl,2′-carboxybensophenone)

The synthesis and characterization of poly(4-vinyl,2′-carboxybenzophenone) ion exchange resin is described. This resin displays a remarkably high capacity for Cu²⁺. Control of pH permits selective adsorption and estimation of Fe³⁺. This ion-exchanger is quite stable to loading acid washing cycles. © 1995 John Wiley & Sons, Inc.     

Advanced oxidation processes for decolorization of aqueous solution containing acid red G azo dye

Some investigations concerning the decolorization of Acid Red G azo dye by photooxidation with hydrogen peroxide were performed. The influences of pH, oxidant concentration, and the presence of Fe²⁺ or other metal ions (Co²⁺, Cu²⁺, Ni²⁺, Mn²⁺) as potential catalysts, were investigated. The best results were obtained in the presence of ferrous ions in acid and neutral media. The other ions are not as effective as Fe²⁺ for dye decolorization. Co²⁺ and Cu²⁺ ions have a catalytic action, at low concentration, within a wide range of pH. Ni²⁺ and Mn²⁺ ions have no catalytic effect in photooxidation with hydrogen peroxide at acid Ni²⁺ and Mn²⁺ ions have no catalytic effect in photooxidation with hydrogen peroxide at acid pH values, but show a weak action in alkaline media.     

Interaction Structure and Affinity of Zwitterionic Amino Acids with Important Metal Cations (Cd2+, Cu2+, Fe3+, Hg2+, Mn2+, Ni2+ and Zn2+) in Aqueous Solution: A Theoretical Study

Heavy metals are non-biodegradable and carcinogenic pollutants with great bio-accumulation potential. Their ubiquitous occurrence in water and soils has caused serious environmental concerns. Effective strategies that can eliminate the heavy metal pollution are urgently needed. Here the adsorption potential of seven heavy metal cations (Cd²⁺, Cu²⁺, Fe³⁺, Hg²⁺, Mn²⁺, Ni²⁺ and Zn²⁺) with 20 amino acids was systematically investigated with Density Functional Theory method. The binding energies calculated at B3LYP-D3/def2TZVP level showed that the contribution order of amino acid side chains to the binding affinity was carboxyl > benzene ring > hydroxyl > sulfhydryl > amino group. The affinity order was inversely proportional to the radius and charge transfer of heavy metal cations, approximately following the order of: Ni²⁺ > Fe³⁺ > Cu²⁺ > Hg²⁺ > Zn²⁺ > Cd²⁺ > Mn²⁺. Compared to the gas-phase in other researches, the water environment has a significant influence on structures and binding energies of the heavy metal and amino acid binary complexes. Collectively, the present results will provide a basis for the design of a chelating agent (e.g., adding carboxyl or a benzene ring) to effectively remove heavy metals from the environment.     

Partially substituted lithium manganese oxides as 3 V cathode materials for secondary lithium batteries

Low temperature synthesis and electrochemical properties of partially substituted lithium manganese oxides are reported. We demonstrate various metallic cations (Cu²⁺, Ni²⁺, Fe³⁺, Co³⁺) can be incorporated in the 3 V layered cathodic material Li_0.45MnO_2.1. New compounds Li_0.45Mn_0.88Fe_0.12O_2.1, Li_0.45Mn_0.84Ni_0.16O_2.05, Li_0.45Mn_0.79Cu_0.21O_2.3, Li_0.45Mn_0.85Co_0.15O_2.3 are prepared. These 3 V cathode materials are characterized by the same shape of discharge-charge profiles but different values of the specific capacity, between 90 mAh g⁻¹ and 180 mAh g⁻¹. The best results in terms of capacity and cycle life are obtained with the selected content of 0.15 Co per mole of oxide, as the optimum composition. The high kinetics of Li⁺ transport in Li_0.45Mn_0.85Co_0.15O_2.3 compared to that in the Co-free material is consistent with a substitution of Mn(III) by Co(III) in MnO₂ sheets.     

Kinetic Study of Metals Sorption on a Resin Modified with Tetrakis(carboxyphenyl)Porphyrin

 The sorption of metal ions (e.g. Cd²⁺, Cu²⁺, Ni²⁺ and Pb²⁺) from aqueous solution on the anion exchange resin Amberlite IRA-904 modified with tetrakis(4-carboxyphenyl)porphyrin (TCPP) was studied in batch equilibrium experiments. The influence of operating variables such as initial pH and contact time between solution and the resin on the equilibrium parameters was measured. The selectivity order of investigated metal ions was evaluated as follows: Pb²⁺ > Ni²⁺ > Cu²⁺ > Cd²⁺. The matrix cations, such as Mg²⁺ and Ca²⁺, exhibit very low affinity for TCPP-modified resin. The rate uptake of the sorption procedure is predominantly controlled by film diffusion. The best retention kinetic was observed for lead where half the saturation of the TCPP-modified sorbent was achieved in less than 5 min. Author for correspondence. E-mail: kryspyrz@chem.uw.edu.pl Received November 20, 2002; accepted January 26, 2003 Published online May 5, 2003     

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%.