Studying the sorption kinetics on peat ions of iron(III) and copper(II) from wastewater

The sorption kinetics on the peat of copper(II) and iron(III) ions from model solutions are studied. The sorption process takes place quickly and is almost complete after 20 minutes. Based on the processing of the experimental absorption curves of the equations of chemical kinetics and diffusion it is established that the sorption process is in the diffusion mode. The stage of the chemical interaction of the metal ions with the functional groups of peat also contributes to the overall speed of the process. The efficiency of the sorption process is determined and the possibility of Using peat as a sorbent for purifying wastewater from the copper( II) and iron(III) ions at industrial sites is shown.     

Itaconic copolymer modified loess for high-efficiently removing copper ions from wastewater

Using Loess of clay (LC) which is low-cost, highly hydrophilic and small granule materials, biocompatible itaconic acid (IA), 2-hydroxyethyl methacrylate (HEMA) and N-vinyl-2-pyrrolidone (NVP) as functional monomers, a novel biocompatible polymer composite adsorbent (LC/PIHN) was prepared by in-situ copolymerization. It was applied to remove copper ions from wastewater, and the mechanism of adsorption was investigated. It showed that the Cu(II) removal was more than 99.8% at room temperature. The adsorption kinetics and isotherms of LC/PIHN fit the pseudo-second-order model and the Freundlich model, respectively. In summary, LC/PIHN is a kind of biocompatible, low-cost and excellent polymer composite adsorbent for removing heavy metal ions from wastewater.     

Biosorption of copper ions from aqueous solutions by Spirulina platensis biomass

In this study, the economically important micro-alga (cyanobacterium) Spirulina platensis was used as biosorbent for the removal of copper from aqueous solutions. The cyanobacterium was exposed to various concentrations of copper and adsorption of copper by the biomass was evaluated under different conditions that included pH, contact time, temperature, concentration of adsorbate and the concentration of dry biomass. Increased adsorption of copper by the non-living biomass was recorded with gradually increasing pH, and a maximal uptake by the biomass was observed at pH 7. The adsorption of copper was found to increase gradually along with decrease in biomass concentration. Biosorption was found to be at a maximum (90.6%), in a solution containing 100 mg copper/L, at pH 7, with 0.050 g dry biomass and at 37 °C with 90 min of contact time. Analysis of the spectrum obtained with atomic absorption spectrophotometer (AAS), indicated that the adsorbent has a great potential to remove copper from aqueous media contributing to an eco-friendly technology for efficient bioremediation in the natural environment.     

Use of activated carbon materials for wastewater treatment to remove Ni(II), Co(II), and Cu(II) ions

The sorption activity of UVIS-AK activated carbon fiber with respect to the Co(II), Ni(II), and Cu(II) cations was studied. The possibility of using this fiber for industrial wastewater treatment to remove heavy metal ions was examined.     

Using xanthated Lagenaria vulgaris shell biosorbent for removal of Pb(II) ions from wastewater

Chemically modified Lagenaria vulgaris shell was applied as a new sorbent for the removal of lead (II) ions from aqueous solution in a batch process mode. The influence of contact time, initial concentration of lead (II) ions, initial pH value, biosorbent dosage, particle size and stirring speed on the removal efficiency was evaluated. Biosorbent characterization was performed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Four kinetic models (pseudo-first order, pseudo-second order, Elovich model and Intraparticle diffusion model) were used to determine the kinetic parameters. The experimental results were fitted to the Langmuir, Freundlich, Dubinin–Radushkevich and Temkin models of isotherm. Pseudo-second order kinetic model and Langmuir isotherm model best fitted the experimental data. Sorption process is obtained to be fast and equilibrium was attained within 40 min of contact time. The maximum sorption capacity was 33.21 mg g^?1. Biosorption was highly pH-dependent where optimum pH was found to be 5. The results of FTIR and SEM analysis showed the presence of new sulfur functional groups. This study indicated that xanthated Lagenaria vulgaris shell could be used as an effective and low-cost biosorbent for the removal of lead (II) ions from aqueous solution.     

Chelating ionophore based membrane sensors for copper(II) ions

Acetylacetone, ethylacetoacetate and salicyldehyde, are reported to form chelates with copper of high stability as compared to other metals. Therefore, PVC based membranes of bis[acetylacetonato] Cu(II) (A), bis[ethylacetoacetate] Cu(II) (B) and bis[salicyldehyde] Cu(II) (C) have been investigated as copper(II) selective sensors. The addition of sodium tetraphenylborate and various plasticizers, viz., DOS, TEHP, DOP, DBP and TBP have been found to substantially improve the performance of the sensors. The membranes of various compositions of the three chelates were investigated and it was found that the best performance was obtained for the membrane of composition A (1%): PVC (33%): TBP (65%): NaTPB (1%). The sensor shows a linear potential response to Cu(II) over wide concentration range 2.0 × 10⁻⁶ to 1.0 × 10⁻¹ M (detection limit 0.1 ppm) with Nernstian compliance (29.3 mV decade⁻¹ of activity) between pH 2.6 and 6.0 with a fast response time of 9 s. The potentiometric selectivity coefficient values as determined by match potential method (MPM) indicate excellent selectivity for Cu²⁺ ions over interfering cations. The sensor exhibits adequate shelf life (3 months) with good reproducibility (S.D. ±0.2 mV). The sensor has been used in the potentiometric titration of Cu²⁺ with EDTA. The utility of the sensor has been tested by determining copper in vegetable foliar and multivitamin capsule successfully.     

Fluorescent nanoparticles assembled from a poly(ionic liquid) for selective sensing of copper ions

Fluorescent nanoparticles were formed from a poly(ionic liquid) through ion interactions. The fluorescent nanoparticles show highly fluorescent intensity and stability to UV light irradiation and were utilized for highly sensitive and selectivity fluorescent sensor of copper ion.     

A magnetic copper(II)-imprinted polymer for the selective enrichment of trace copper(II) ions in environmental water

We have developed a convenient, selective and reliable method for the rapid enrichment of trace quantities of Cu(II) by using a magnetic Cu(II) ion-imprinted polymer. This is followed by their determination by FAAS. The imprints were prepared by using (a) Cu(II) ions as the template, (b) 3-aminopropyltriethoxysilane as both the functional monomer and the crosslinking agent, and (c) Fe₃O₄ as the magnetic component. Enrichment is carried out in a single step, and adsorbed copper ions can be separated from the sample solution by applying a strong magnet. The effects of pH, elution condition, amount of imprint, and of potentially interfering ions were evaluated. Under the optimal conditions, the detection limit and enrichment factor are 0.3?μg L^?1 and 100, respectively, and the recovery is >95?%. The procedure was successfully applied in the enrichment and detection of trace copper ions in environmental water.

Extraction of Co(II) ions from aqueous solutions with thermally activated dolomite

It was found that thermal activation of dolomite at 700–900°C may increase the sorption capacity of the samples up to 520 mg g^?1. It was shown that the most effective sorbent for Co²⁺ ions may be obtained by calcination of dolomite at 800°C, which allows under dynamic conditions (20 m h^?1) purifi cation of 500 column volumes of an aqueous solution with a Co(II) concentration of 10 mg L^?1 to the maximum allowable concentration.     

Adsorption of copper(II) ions from aqueous solutions on alumina industrial wastes

Equilibrium adsorption of copper(II) ions on red mud (alumina industrial wastes) modified by various methods was studied. The effect exerted by the nature the modifier (NaHSO₄, NaCl + HCl, and H₂SO₄) on the sorption activity of red mud was determined.     

Separation of copper (II) ions from humic complexes with oxine-impregnated emulsion globules

A water-in-oil type emulsion containing oxine has been used for the discrimination of copper(II) ions and copper-humic complexes in aqueous solutions. A toluene solution containing oxine and nonionic surfactant (Span-80) was vigorously mixed with 1 mol/L HCl by ultrasonic irradiation. The resulting emulsion was added to water and dispersed by stirring as numerous small globules. Copper(II) ions were quantitatively permeated across the oil layer and incorporated in the tiny droplets of HCl, whereas copper-humic complexes remained in the sample solution. After collecting the dispersed emulsion globules, they were destroyed by heating to segregate the aqueous (HCl) and organic (toluene) phases. The copper in the aqueous phase was determined by graphite-furnace atomic absorption spectrometry (GFAAS). The analytical results agreed with those obtained by the adsorption method, where negatively charged humic complexes were selectively collected on a macroreticular anion exchanger Sephadex A-25 column. The conventional liquid-liquid extraction did not offer a chemical speciation because copper(II) ions and humic complexes were simultaneously extracted into the organic phase. The proposed emulsion method was successfully applied to the analysis of river water samples.     

Separation of copper (II) ions from humic complexes with oxine-impregnated emulsion globules

A water-in-oil type emulsion containing oxine has been used for the discrimination of copper(II) ions and copper-humic complexes in aqueous solutions. A toluene solution containing oxine and nonionic surfactant (Span-80) was vigorously mixed with 1 mol/L HCl by ultrasonic irradiation. The resulting emulsion was added to water and dispersed by stirring as numerous small globules. Copper(II) ions were quantitatively permeated across the oil layer and incorporated in the tiny droplets of HCl, whereas copper-humic complexes remained in the sample solution. After collecting the dispersed emulsion globules, they were destroyed by heating to segregate the aqueous (HCl) and organic (toluene) phases. The copper in the aqueous phase was determined by graphite-furnace atomic absorption spectrometry (GFAAS). The analytical results agreed with those obtained by the adsorption method, where negatively charged humic complexes were selectively collected on a macroreticular anion exchanger Sephadex A-25 column. The conventional liquid-liquid extraction did not offer a chemical speciation because copper(II) ions and humic complexes were simultaneously extracted into the organic phase. The proposed emulsion method was successfully applied to the analysis of river water samples. Received: 14 April 1998 / Revised: 22 July 1998 / Accepted: 27 July 1998     

Conditions for the formation of copper nanoparticles by reduction of copper(II) ions with hydrazine hydrate solutions

Optimal conditions were found for the preparation of copper nanoparticles in aqueous solution via reduction of copper(II) ions with hydrazine hydrate. The effects of ligand environment of copper(II) in the initial solution (hydrate, ammonia, citrate, and glycine complexes), concentration, pH, surfactants, temperature, and mode of heating were examined. The obtained colloidal systems were studied by optical spectroscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction, and atomic force microscopy. The examined colloids were found to contain generally spherical copper nanoparticles with a diameter of about 10 nm, which were coated with a copper(I) or copper(II) oxide and hydroxide film.     

Diffusion-layer model for copper solid-state chalcocite membrane electrode; sensitivity to copper(II) ions

The diffusion-layer model for the chalcocite (Cu(2)S) membrane electrode is discussed. It is equivalent to a simpler model based on exchange reactions at the electrode surface. The chalcocite is sensitive to copper(I) and copper(II) ions and the theoretically predicted response is in good agreement with experimental data. The membrane is a conductor, but this does not significantly affect its function as an ion detector. The limitation of the electrode is the membrane solubility as shown when Cu(II) ions in contrast to copper(I) ions are strongly complexed.     

Determination of copper(I) and copper(II) ions after complexation with bicinchoninic acid by CE

A facile, sensitive, and selective method was developed for the simultaneous separation and determination of copper(I) [Cu(+)] and copper(II) [Cu(2+)] ions using CE with direct UV detection. The copper ions were complexed with a 1.5 mM bicinchoninic acid disodium salt solution at pH 8.7 prior to analysis. Acetate buffer (2 mM) was used as the CE running buffer. Parameters affecting CE separation such as sample pH, applied voltage, concentration of complexing agent, nature of the buffer solution, and interferences by other metal ions, were evaluated. The LODs for Cu(+) and Cu(2+) were 3.0 and 2.5 microg/mL (S/N = 3), respectively. The developed method allows the simultaneous determination of Cu(+) and Cu(2+) in less than 5 min with RSDs of between 5.3 and 9.5% for migration time and between 3.4 and 9.7% for peak areas, respectively. At optimum conditions, the percentage recoveries of Cu(+) and Cu(2+) were found to be 99.4 and 99.5%.