Separation and Recovery of Some Metal Ions Using Pan Sorbed Zinc Silicate as Chelating Ion Exchanger

Abstract

A new inorganic ion exchanger zinc silicate has been synthesized. Its properties such as ion exchange capacity, heat effect and stability etc. have been studied. Sorption of PAN over zinc silicate formed a chelate ion exchanger which showed greater selectivity for some metal ions especially for Cu²⁺, Ni²⁺, Co²⁺, Fe³⁺, Ag⁺, Ag³⁺ and Pt⁴⁺. Selectivity has been determined on the basis of distribution coefficients of these metal ions. Separations of Pt(IV) from Fe(III), Au(III) from Fe(III), Ag(I) from Cu(II) and Au(III) from Cu(II) have been reported. The recovery of Pt(IV) and Au(III) from dilute solutions has also been studied.     

Role of Ion exchange in permeation processes

The single ion transport of transition metal ions like Cu²⁺, Co²⁺, Ni²⁺ and Zn²⁺ were carried out through the H⁺ and alkali metal ion forms of Nafion membrane. These studies showed that the ion exchange selectivity coefficient of the permeating ion had an effect on its transport process. It was found that the diffusion coefficient values (D) were directly proportional to the selectivity coefficient (K). This shows that the initial stage of permeation is governed by ion exchange process (effect of K on D).     

A Schiff base‐grafted nanoporous silica material as a reversible optical probe for Hg2+ ion in water

A novel organic–inorganic silica‐based fluorescent probe was designed, synthesized and characterized by different techniques such as XRD, BET, TGA, and FT‐IR. The fluorescence properties of the probe were studied in the presence of a variety of metal‐ions in water. The results revealed that various metal‐ions negligibly vary the emission intensity of the probe except for Hg²⁺, which quenched the intensity dramatically. The selectivity of the probe toward Hg²⁺ ion was further investigated in the presence of common competing metal‐ions and the results demonstrated the high selectivity of the probe toward Hg²⁺ ion. The fluorescence emission of the probe was also studied as a function of the concentration of Hg²⁺ ion. A nanomolar limit of detection was estimated for Hg²⁺, indicating a high sensitivity. Furthermore, the probe showed INHIBIT‐type logic behavior with Hg²⁺ and H⁺ as inputs. Also, the optimum pH range was studied in addition to reversibility and real world applicability of the probe.     

Studies on Synthesis of a Cycloheptapeptide and Effects of Different Metal Ions on the Cyclization

ＩｎｔｒｏｄｕｃｔｉｏｎＣｙｃｌｉｃｐｅｐｔｉｄｅｓ ,ｗｈｉｃｈａｒｅｃｏｎｓｔｒａｉｎｅｄｃｏｎｆｏｒｍａ ｔｉｏｎａｌｌｙａｎｄｍｏｒｅｒｅｓｉｓｔａｎｔｔｏｐｒｏｔｅａｓｅｄｉｇｅｓｔｉｏｎｓｔｈａｎｔｈｅｉｒｌｉｎｅａｒｐｒｅｃｕｒｓｏｒｓ ,ｈａｖｅｂｅｅｎｏｆｇｒｅａｔｉｎｔｅｒｅｓｔａｓｓｙｎｔｈｅｔｉｃｔａｒｇｅｔｓｂｏｔｈａｓｐｏｔｅｎｔｉａｌｄｒｕｇｌｅａｄｓａｎｄａｓｍｏｄｅｌｓｆｏｒｃｏｎ ｆｏｒｍａｔｉｏｎａｌａｎａｌｙｓｉｓ .1 4 Ｃｕｒｒｅｎｔｍｅｔｈｏｄｓｆｏｒｓｙｎｔ…     

Preparation of PSSS‐grafted polysulfone microfiltration membrane and its rejection and removal properties towards heavy metal ions

3‐Hydroxy‐N,N‐diethylaniline (HDEA) as a tertiary aromatic amine was introduced onto the surface of chloromethylated polysulfone (CMPSF) microfiltration membrane through modification reaction, resulting in the modified membrane PSF‐DEA. A redox surface‐initiating system (DEA/APS) was constituted by the bonded tertiary aromatic amine group DEA and ammonium persulfate (APS) in aqueous solution, and so, the free radicals formed on the membrane initiated sodium p‐styrenesulfonate (SSS) as an anionic monomer to produce graft polymerization, getting the grafting‐type composite microfiltration membrane, PSF‐g‐PSSS membrane. Subsequently, the adsorption property of PSF‐g‐PSSS membrane for three heavy metal ions, Pb²⁺, Zn²⁺, and Hg²⁺ ions, was fully examined, and the rejection performance of PSF‐g‐PSSS membrane towards the three heavy metal ions was emphatically evaluated via permeation experiments. The experimental results show that by the initiating of the surface‐initiating system of DEA/APS, the graft polymerization can smoothly be carried out under mild conditions. PSF‐g‐PSSS membrane as a functional microfiltration membrane has strong adsorption ability for heavy metal ions by right of strong electrostatic interaction (or ion exchange action) between the anionic sulfonate ions on the membrane and heavy metal ions. The order of adsorption capacity is Pb²⁺ > Zn²⁺ > Hg²⁺, and the adsorption capacity of Pb²⁺ ion gets up to 2.18 μmol/cm². As the volume of permeation solutions, in which the concentrations of the three metal ions are 0.2 mmol/L, are in a range of 50 to 70 mL, the rejection rate of PSF‐g‐PSSS membrane for the three heavy metal ions can reach a level of 95%, displaying a fine rejection and removing performance towards heavy metal ions.     

2,4‐Dichlorophenyl Acrylate/8‐Quinolinyl Methacrylate Copolymers: Ion‐Exchange Study

The chelating ion‐exchange properties of the 2,4‐dichlorophenyl acrylate (2,4‐DCPA)/8‐quinolinyl methacrylate (8‐QMA) copolymers, synthesized using different monomer feed ratios, were investigated by the batch equilibrium method. Five metal ions Cu⁺², Ni⁺², Co⁺², Zn⁺², and Fe⁺³ were used to evaluate the cation‐exchanger capability of 2,4‐DCPA‐co‐8‐QMA copolymers. The ion‐exchange study was carried out for three different experimental variables viz., pH of the aqueous medium, ionic strength of electrolyte and shaking time. It was observed that due to the presence of a pendant ester‐bound quinolinyl group, the copolymers are better suited as cation exchangers.     

Synthesis of poly(hydroxamic acid) ligand from polymer grafted corn‐cob cellulose for transition metals extraction

Poly(hydroxamic acid) ligand was synthesized using ester functionalities of cellulose‐graft‐poly(methyl acrylate) copolymer, and products are characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, high‐resolution transmission electron microscopy, and X‐ray photoelectron spectroscopy analysis. The poly(hydroxamic acid) ligand was utilized for the sensing and removal of transition metal ions form aqueous solutions. The solution pH is found a key factor for the optical detection of metal ions, and the reflectance spectra of the [Cu‐ligand]ⁿ⁺ complex were observed to be the highest absorbance 99.5% at pH 6. With the increase of Cu²⁺ ion concentration, the reflectance spectra were increased, and a broad peak at 705 nm indicated that the charge transfer (π‐π transition) complex was formed. The adsorption capacity with copper was found to be superior, 320 mg g^?1, and adsorption capacities for other transition metal ions were also found to be good such as Fe³⁺, Mn²⁺, Co³⁺, Cr³⁺, Ni²⁺, and Zn²⁺ were 255, 260, 300, 280, 233, and 223 mg g^?1, respectively, at pH 6. The experimental data show that all metal ions fitted well with the pseudo‐second‐order rate equation. The sorption results of the transition metal ions onto ligand were well fitted with Langmuir isotherm model (R² > 0.98), which implies the homogenous and monolayer character of poly(hydroxamic acid) ligand surface. Eleven cycles sorption/desorption process were applied to verify the reusability of this adsorbent. The investigation of sorption and extraction efficiency in each cycle indicated that this new type of adsorbent can be recycled in many cycles with no significant loss in its original detection and removal capability. Copyright © 2016 John Wiley & Sons, Ltd.     

Preconcentration of Metal Ions with Anion-Exchange Resin

A method to preconcentrate metal ions employed an anion-exchange resin was studied. Metal ions were first chelated with ethylenediaminetetraacetic acid (EDTA), then trapped on an enrichment column packed with anion-exchange resin. The major interfering ions, e.g. calcium and magnesium were excluded from enrichment by appropriate adjustment of pH. Desorption of the trapped metals was effected by elution with HCl (0.1 M). Recoveries of Cu²⁺, Ni²⁺, Co²⁺, Pb²⁺, Zn²⁺ reached 99%. By comparison with preconcentration methods using cation-exchange resin, this method has the advantages of selectivity, quantitative recovery, small cost of operation, and simple procedure.     

Rational Construction of Polymeric Cadmium(II) Benzimidazole for Transition Metal Ion Exchange

A 1D double‐helical coordination polymer {[Cd(pbbm)₂]₂(ClO₄)₄(H₂O)₂}_n ( 1 ) was successfully constructed by the reaction of Cd(ClO₄)₂ · 6H₂O with 1,1′‐(1,5‐pentanediyl)bis‐1H‐benzimidazole (pbbm). Interestingly, polymer 1 exhibits highly selective capacity for the ionic exchange of Zn²⁺ and Cu²⁺ over Co²⁺ and Ni²⁺ ions in the crystalline solid state when the crystals of 1 are immersed in the aqueous solutions of the perchlorate salts of Cu²⁺, Zn²⁺, Co²⁺, and Ni²⁺ ions, respectively, which indicates that central Cd^II ion exchange might be considered as being dominated by the coordination ability of metal ions to free functional groups, ionic radii of exchanged metal ions, and the solution concentration of adsorbed metal salts. The parent material‐ and ion‐exchange‐induced products are identified by FT‐IR spectroscopy, PXRD patterns as well as SEM and EDS measurements. In addition, the thermal stability of 1 was also investigated.     

Indirect ultraviolet detection of alkaline earth metal ions using an imidazolium ionic liquid as an ultraviolet absorption reagent in ion chromatography

A convenient and versatile method was developed for the separation and detection of alkaline earth metal ions by ion chromatography with indirect UV detection. The chromatographic separation of Mg²⁺, Ca²⁺, and Sr²⁺ was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid as the mobile phase, in which the imidazolium ionic liquid acted as an UV‐absorption reagent. The effects of imidazolium ionic liquids, detection wavelength, acids in the mobile phase, and column temperature on the retention of Mg²⁺, Ca²⁺, and Sr²⁺ were investigated. The main factors influencing the separation and detection were the background UV absorption reagent and the concentration of hydrogen ion in ion chromatography with indirect UV detection. The successful separation and detection of Mg²⁺, Ca²⁺, and Sr²⁺ within 14 min were achieved using the selected chromatographic conditions, and the detection limits (S /N = 3) were 0.06, 0.12, and 0.23 mg/L, respectively. A new separation and detection method of alkaline earth metal ions by ion chromatography with indirect UV detection was developed, and the application range of ionic liquids was expanded.     

Sorption investigation on the removal of metal ions from aqueous solutions using chelating terpolymer resin

A novel chelating terpolymer resin has been synthesized from anthranilic acid, phenylhydrazine, and formaldehyde by condensation in glacial acetic acid. The structure of the chelating resin was clearly elucidated by use of a variety of spectral techniques, for example FTIR, and ¹H and ¹³C NMR spectroscopy. The average molecular weight of the terpolymer resin was determined by gel-permeation chromatography. The empirical formula and empirical weight of the resin were determined by elemental analysis. The physicochemical properties of the terpolymer resin were determined. Scanning electron microscopy was used to establish the surface features of the chelating resin. The ion-exchange behaviour of the resin for specific metal ions, viz. Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, and Pb²⁺, was evaluated by a batch equilibrium method. The study was extended to three variations: evaluation of metal ion uptake in the presence of different electrolytes at different concentrations; evaluation of metal ion uptake at different pH; and evaluation of metal ion uptake at different times. Further, the reusability of the resin was also determined to assess the efficiency of the resin after a few cycles of sorption. From the results it was observed that the resin acts as an effective chelating ion-exchanger.     

Effect of Complexation on Photocatalytic Degradation of Dissolved Organic Nitrogen Compounds

Abstract

The effect of metal ions on TiO₂ mediated photocatalytic oxidation for the determination of dissolved organic nitrogen compounds is investigated. Ethylenediaminetetraaceticacid was chosen as a model molecule for DON compounds. At pH 2, 5, 7, and 10 aqueous EDTA solutions were irradiated at 254 nm in the presence of Fe²⁺, Cu²⁺, Zn²⁺, Ni²⁺ or Co²⁺ ions. The sum of produced nitrate, nitrite, and ammonium ion concentrations gave the total oxidation recovery. At low pH, the photocatalytic oxidation recoveries of Fe‐EDTA, Ni‐EDTA, and Co‐EDTA were significantly lower than the photocatalytic degradation of EDTA. The presence of free Fe²⁺, Ni²⁺, and Co²⁺ ions decreased the photocatalytic oxidation recovery. The [NH₄ ⁺]/[NO₃ ^?] ratio was higher for Cu‐EDTA.     

Highly Efficient and Selective Membrane Transport of Silver(I) Using Dibenzodiaza‐15‐Crown‐4 as a Selective Ion Carrier

A chloroform membrane system containing dibenzodiaza‐15‐crown‐4 was found to be a highly efficient and selective transport of Ag⁺ ions through a chloroform liquid membrane. In the presence of thiosulfate ion as a suitable ion stripping agent in the receiving phase, the amount of silver transported across the liquid membrane after 105 minis 95 ± 1.3%. The selectivity of Ag⁺transport from aqueous solutions containing Tl⁺, Pb²⁺, Cd²⁺, Ni²⁺, Co²⁺, K⁺, Ca²⁺, Sr²⁺, Hg²⁺, Zn²⁺, Cu²⁺was investigated. The interfering effect of Cu²⁺ ions was drastically diminished in the presence of EDTA as a proper masking agent in the source phase.     

Modification of Rice Straw for Heavy Metal Ion Adsorbents by Microwave Heating

Summary: Cellulose in rice straw was chemically modified by phosphorylation using conventional heating or microwave heating. Rice straw pretreated by NaOH solution gave the highest phosphorus content when it was phosphorylated using microwave heating at 450 watt (7.07%P, ion exchange capacity 2.60 meq/g). The 3 hour-reaction in oil bath yielded the modified rice straw with lower of phosphorus content (6.32%P) and higher ion exchange capacity (2.99 meq/g) than that of microwave heating. The feasibility of the modified rice straw as cation sorbents for removing heavy metal was investigated. Cd²⁺, Cr³⁺ and Pb²⁺ were used as sorbates. In sorption test of 40 ppm with 2.0 g/L of the modified rice straw, both modified rice straws could adsorb metal ions faster than the commercial ion exchange resin (dowax) at the time less than 60 min. The modified rice straw prepared by microwave heating (A-MCW2) could remove 90% of Cd²⁺ and Cr³⁺ in 60 minutes and remove 99% of Pb²⁺ after 30 min.     

Thermodynamics of exchange in clays: Ion exchange equilibria of transition metals and sodium ions on illite

Ion exchange equilibria of bivalent transition metal ions have been studied at 20, 30 and 45°C on illite surface. The exchange isotherms and free energy changes indicate a higher preference of the illite surface for the metal ions. Cd²⁺ and Mn²⁺ ions were preferred throughout the entire range while reversal of behaviour occurred during Cu²⁺, Zn²⁺ and Co²⁺ ions exchange on the illite surface. Enthalpy changes suggested a stronger preference of transition metal ions for the illite surface. Entropy changes indicated an increase in the order of system. The surface phase coefficients of the cations showed that with increasing metal ion saturationf _m continuously increases whilef _Na decreases. The excess thermodynamic functions snowed that the exchange reactions were non-ideal.     

A New Fluorescent Chemosensor for Metal Ions Based upon 1,8‐Naphthalimide and 8‐Hydroxyquinoline

A new fluorescent chemosensor based upon 1,8‐naphthalimide and 8‐hydroxyquinoline was synthesized, and its fluorescent properties in the presence of different metal cations (Hg²⁺, Ag⁺, Zn²⁺, Fe²⁺, Cd²⁺, Pb²⁺, Ca²⁺, Cu²⁺, Mg²⁺, and Ba²⁺) were investigated. It displayed fluorescence quenching with some heavy and transition metal (HTM) ions, and the quenching strongly depended on the nature of HTM ions.     

Modified Capillary Electrophoresis for Highly Sensitive and Selective Detection of Hg2+ in Natural Water

A novel capillary with high sensitivity and selectivity for mercury ion detection based on modified nanosize silica has been designed and synthesized. The obtained modified capillary was applied to separate and determine mercury ion by capillary electrophoresis with a laser‐induced fluorescence detector. The optimal experimental conditions were determined by evaluating various controlling factors: running buffer hexamine‐HCl 15 mmol L^?1, pH=5.2, separation voltage 30 kV and temperature 25 °C. The modified capillary exhibited excellent sensitivity and selectivity for Hg2+ over other coexisting metal ions (K⁺, Ag⁺, Ca2⁺, Mg²⁺, Ba²⁺, Ni²⁺, Cd²⁺, Pb²⁺ and Zn²⁺ increased to 10000 times of Hg²⁺, Cu²⁺ increased to 5000 times) in aqueous solution, and was successfully applied to the determination of Hg²⁺ in natural water samples and displayed satisfactory results.     

Utilization of a spiropyran derivative in a polymeric film optode for selective fluorescent sensing of zinc ion

Spiropyrans are the most studied families of func- tional materials due to their reversible structural con- version in response to external optical, chemical, and thermal stimulation[1]. Irradiation with ultraviolet light causes formation of an extended π-conjugation open form (merocyanine form) by heterolytic cleavage of the C (spiro)-O bond, which generates an intense ab- sorption in the visible region. Under the irradiating of visible light, the opened form will come back to the closed spi…     

Selectivity study of strongly acidic cation exchange resin Amberlite IR-120

The thermodynamic measurements was carried out to study the selectivity of cation exchange resin Amberlite IR-120 in protonated form with respect to Mg²⁺, Ca²⁺, Sr²⁺ and Ba²⁺ ions in solution. The equilibrium constant K was calculated using the activity coefficients of ions in solution as well as in the resin. The K values calculated for the reacting systems increase with temperature that suggests the endothermic exchange reactions with estimated enthalpy values of 38.8, 20.6, 8.45, and 7.24 kJ mol⁻¹, respectively. On the basis of calculated parameters, the selectivity of ion exchange resin with respect to various bivalent ions in the solution was predicted. The method used in our experimental work provides a basis for characterization of ion exchange resins, which can be promising materials for efficient separation of ions from industrial waste effluents.     

STUDY ON THE SYNTHESIS OF POLYSTYRENESUPPORTED MACROCYCLIC MERCAPTAL CHELATING RESIN AND ITS PROPERTIES

Chelating resin with macrocyclic mercaptal group supported on macroporous polystyrene beads was synthesized, which showed good selectivity to Hg~(2+): its complexing capacity amounted to 30—60 mg Hg~(2+)/g resin, two orders of magnitude greater than for other metal ions such as Ca~(2+), Zn~(2+), Cd~(2+), Pb~(2+) etc. This resin could restore the activity of urease which had been deactivated by poisoning with Hg~(2+). Its restoring power was far better than that of the mercapto-resin and common anionic exchange resins. It showed some promising use as an oral polymeric detoxifying drug for mercury poisoning.