Adsorption of Ni(II) and Co(II) Using Microballoons Containing Mg-Silicate and CYANEX923 Prepared by the Emulsion Liquid Membrane System

Abstract

The Mg-silicate microballoons containing CYANEX923 were prepared by W/O/W emulsion. The diameter of obtained micro-sphere particles was ～10 µm and shell thickness was 2 µm. The adsorption of Co(II) and Ni(II) from aqueous solutions using prepared micro-sphere particles was investigated. Experiments were carried out as a function of solute concentration and temperature (25–60°C). Several kinetic models were used to test the experimental rate data and to examine the controlling mechanism of the adsorption process. Equilibrium adsorption data were analyzed using Langmuir isotherm model. The results indicated that prepared micro-sphere particles can be used as an efficient adsorbent for the removal of Ni(II) and Co(II) from aqueous solution.     

ION EXCHANGE CHARACTERISTICS OP A NEW MANGANESE OXIDE : STRUCTURAL FEATURES AND ALKALI CATION EXCHANGE

Three hydrous manganese oxides were prepared by atmospheric oxidation of the hydroxide obtained by alkali addition to MnSO₄ The obtained products appear not to have been described before and their structure is a defect one resembling that of γ-Mn₂O₃ one of the samples contain some Mn(OH)2. The product obtained with ammonia, incontradistinction.to the products prepared with NaOH, has no ion exchange properties. The oxide studied in more detail and prepared with NaOH has the chemical formula N₈₄Mn₁₇O₂₇.13 H₂O. Only some of the Na in the structure could fee exchanged with other alkali ions. Besides, the oxide seems to have exchangeable H+ that can be replaced in neutral solution by K+ and to a greater extent by Cs+ but not by Li+ or Na+.Alkali ion exchanges were found to be thermodynamically irreversible, which seems to be due to differences in the defect crystalline structures of the different alkali ion forms of the oxide. A tentative picture of ion exchange mechanisms is given.     

Silica functionalized by pyridinecarboximidamides as a novel sorbent of heavy metals ions

ABSTRACT

Two novel sorbents, obtained as a result of surface modification of silica gel for the Cu(II), Co(II) and Ni(II) removal from aqueous solutions were proposed. For the modification, 3-chloropropyltrimethoxysilane, N’-hydroxy-N,N-dioctylpyridine-3-carboximidamide and N’-hydroxy-N,N-dioctylpyridine-4-carboximidamides were used. A series of basic tests on the sorption of Cu(II), Co(II) and Ni(II) were carried out and the presented results indicated that the novel sorbents were able to remove all tested metals ions from the aqueous solutions, and the removal efficiency was dependent on the functionalised agent structure, dosage, metal ions concentration and pH. The Langmuir model also assumed that a monolayer sorption occurred.     

Extraction of Lanthanum and Samarium from Nitrate Medium by some Commercial Organophosphorus Extractants

Abstract

The extraction of lanthanum(III) and samarium(III) from nitrate solutions by some phosphine oxide compounds (Cyanex 921, Cyanex 923, and Cyanex 925) in kerosene was investigated. The influence of the different factors affecting the extraction was studied in detail. The extraction of these metals using the above extractants was compared and the sequence of extraction was found to be Cyanex 921>Cyanex 923?Cyanex 925. The stripping percent of La(III) and Sm(III) by 0.75 M HNO₃ from the loaded organic phase after two stages were 72% and 5.2%, respectively, which could enable a good separation between these two lanthanides.     

Preconcentration of Heavy Metals and Matrix Elimination using Silica Gel Chemically Modified with 2,3‐Dihydroxybenzaldehyde

Abstract

Many direct methods cannot easily be used to measure analytes such as Cd(II), Cu(II), Ni(II), Pb(II), and Zn(II) ions in sea and river water since these elements are present at very low concentration and the sample has a very complex matrix. In this study a method was developed to preconcentrate these ions by solid phase extraction within a column system using a newly synthesised 2,3‐dihydroxy benzaldehyde modified silica gel (SGDHB). Different parameters, such as pH, resin amount, eluent type, eluent volume, sample flow rate, preconcentration factors, and resin capacity were determined for the preconcentration of metal ions with the resin. Samples (125–500 ml) containing metal ions were passed through the column filled with SGDHB resin so that metal ions were retained on the column. The preconcentrated analytes were then eluted with 15 mL of 0.1 M HCl. The metal concentrations in the eluate were measured by FAAS. A sample and eluent flow rate of 1.12 and 0.56 ml/min respectively was used. Estimates of accuracy, precision, and detection limits were determined. In addition, analysis of the CRM LGC 6156 harbor sediment was undertaken, using the resin to isolate the analytes from potential interferences. Good agreement with certified values was obtained, indicating that the method is equally applicable to the analysis of water samples and to digests of solid materials.     

Preparation of Poly(acrylamide-maleic Acid) Resin by Template Polymerization and Its Use for Adsorption of Co(II) and Ni(II)

Poly(acrylamide-maleic acid) resin P(AAm-MA) was prepared by template polymerization. Polyacrylamide PAAm was used as a template for the polymerization of MA in an aqueous solution using gamma rays as the initiator. The effects on the capacity of P(AAm-MA), such as concentration of maleic acid and amount of template polymer, were investigated. P(AAm-MA) has been utilized as an adsorbent for the removal of Co(II) and Ni(II) ions from an aqueous solution. The effects of time of equilibrium, pH, temperatures, and dosage of the adsorbent on the removal of Co(II) and Ni(II) ions have been studied. The equilibrium data were analyzed using the Langmuir and Freundlich isotherm models. The equilibrium process was described well by the Langmuir isotherm model.     

Removal of Cu(II) and Zn(II) Using Lignocellulosic Fiber Derived from Citrus reticulata (Kinnow) Waste Biomass

Abstract

The biosorption of Cu(II) and Zn(II) using dried untreated and pretreated Citrus reticulata waste biomass were evaluated. The Cu(II) and Zn(II) sorption were found to be dependent on the solution pH, the biosorbent dose, the biosorbent particle size, the shaking speed, the temperature, the initial metal ions (800 mg/L), and the contact time. Twenty-eight physical and chemical pretreatments of Citrus reticulata waste biomass were evaluated for the sorption of Cu(II) and Zn(II) from aqueous solutions. The results indicated that biomass pretreated with sulphuric acid and EDTA had maximum Cu(II) and Zn(II) uptake capacity of 87.14 mg/g and 86.4 mg/g respectively. Moreover, the Langmuir isotherm model fitted well than the Freundlich model with R ² > 0.95 for both metal ions. The sorption of Cu(II) and Zn(II) occurred rapidly in the first 120 min and the equilibrium was reached in 240 min. FTIR and SEM studies were also carried out to investigate functional groups present in the biomass and the surface morphological changes of biomass.     

Calcined tetrabutylammonium kaolinite and montmorillonite and adsorption of Fe(II), Co(II) and Ni(II) from solution

Kaolinite and montmorillonite were modified with tetrabutylammonium (TBA) bromide, followed by calcination. The structural changes were monitored with XRD, FTIR, surface area and cation exchange capacity measurements. The modified clay minerals were used for adsorption of Fe(III), Co(II) and Ni(II) ions from aqueous solution under different conditions of pH, time and temperature. The uptake of the metal ions took place by a second order kinetics. The modified montmorillonite had a higher adsorption capacity than the corresponding kaolinite. The Langmuir monolayer capacities for the modified kaolinite and montmorillonite were Fe(III): 9.3 mg g^− 1 and 22.6 mg g^− 1; Co(II): 9.0 mg g^− 1 and 22.3 mg g^− 1; and Ni(II): 8.4 mg g^− 1 and 19.7 mg g^− 1. The modified kaolinite interacted with Co(II) in an endothermic manner, but all the other interactions were exothermic. The decrease of the Gibbs energy in all the cases indicated spontaneous adsorption.     

Process for the Recovery of Cobalt and Nickel from Sulphate Leach Liquors with Saponified Cyanex 272 and D2EHPA

Abstract

In this paper, a process is reported for the recovery of cobalt and nickel from copper raffinate solutions using partially saponified Cyanex 272 and D2EHPA as the extractants. The aqueous feed contains 1.65 g/L cobalt and 16.42 g/L nickel. More than 99.9% cobalt separation was achieved with 0.13 M Cyanex 272 (60% neutralized with alkali) in two counter‐current stages at an aqueous to organic phase ratio of 1.1:1. Co‐extraction of nickel was 0.18% only. Stripping of cobalt from a loaded organic phase was carried out with synthetic spent electrolyte solution at an organic to aqueous phase ratio of 2.5 in two counter‐current stages to generate a pregnant electrolyte solution to produce cobalt metal by electrowinning. Similarly, optimum conditions for nickel extraction with 60% neutralized 1 M D2EHPA at O/A ratio of 1.4 in 2 two stages and stripping of metal with synthetic spent electrolyte at O/A ratio of 1.6 in two stages were standardized. Extraction and stripping efficiencies were >99% and the flowsheet of the process is demonstrated.     

Kinetics of the metal exchange reaction of a Cu(II)-poly(vinyl alcohol) complex with Zn(II)-ethylenediamine-N,N,N′,N′-tetraacetic acid in aqueous solution

The kinetics of the metal exchange reaction between Cu(II)-poly(vinyl alcohol) [Cu(II)-PVA] and Zn(II)-ethylenediamine-N,N,N,N-tetraacetic acid [Zn(II)-EDTA] has been studied by mixing both solutions in a spectrophotometer at pH 10.0 to 11.0, ionic strength =0.10(KNO₃), and 15 to 35°C. The reaction is initiated by the formation of unstable Cu(II)-H-PVA through attack of H⁺ ion on the Cu(II)-PVA complex, and both reactions, ligand exchange and metal exchange, proceed simultaneously. The metal exchange step may be rate determining. The rate equation and rate constants of this reaction were determined as follows: –d[Cu(II)-PVA]/dt=k _0(H)[PVA^–][Cu(II)-PVA] [Zn(II)-EDTA], wherek _0(H)=k ₁+(k₂+k₃)[H⁺],k ₁=5.98±1.64M ^–1 s^–1, andk ₂+k ₃=k₂ K _Cu(II)-H-PVA ^–H +k₃ K _Zn(II)-EDTA ^H =(5.91±0.89)×10⁷ M ^–2 s^–1.     

Chelation of Cu(II), Zn(II), and Fe(II) by Tannin Constituents of Selected Edible Nuts

The tannin fractions isolated from hazelnuts, walnuts and almonds were characterised by colorimetric assays and by an SE-HPLC technique. The complexation of Cu(II) and Zn(II) was determined by the reaction with tetramethylmurexide, whereas for Fe(II), ferrozine was employed. The walnut tannins exhibited a significantly weaker reaction with the vanillin/HCl reagent than hazelnut and almond tannins, but the protein precipitation capacity of the walnut fraction was high. The SE-HPLC chromatogram of the tannin fraction from hazelnuts revealed the presence of oligomers with higher molecular weights compared to that of almonds. Copper ions were most effectively chelated by the constituents of the tannin fractions of hazelnuts, walnuts and almonds. At a 0.2 mg/assay addition level, the walnut tannins complexed almost 100% Cu(II). The Fe(II) complexation capacities of the tannin fractions of walnuts and hazelnuts were weaker in comparison to that of the almond tannin fraction, which at a 2.5 mg/assay addition level, bound Fe(II) by ~90%. The capacity to chelate Zn(II) was quite varied for the different nut tannin fractions: almond tannins bound as much as 84% Zn(II), whereas the value for walnut tannins was only 8.7%; and for hazelnut tannins, no Zn(II) chelation took place at the levels tested.     

Nickel and copper removal study from aqueous solution using new cationic poly[acrylamide/N,N‐DAMB/N,N‐DAPB] super absorbent hydrogel

A new cationic poly[acrylamide/N,N‐diallyl morpholinium bromide/N,N‐diallyl piperidinium bromide] super absorbent hydrogels (H1–H7) were prepared via microwave irradiated free radical cyclopolymerization using different composition. By the swelling study, hydrogel H1 is found to bear good swelling properties amongst all prepared hydrogels. The hydrogel H1 has been characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), and TGA analysis. A batch system was applied to study the adsorption of Ni(II) and Cu(II) from aqueous solutions by hydrogel H1. The effect of treatment time, pH of the medium, amount of adsorbent doses, and initial feed concentration of metal ion on adsorption of Ni(II) and Cu(II) from their solution were also investigated. Adsorption of Ni(II) and Cu(II) increases with the increase in treatment time, adsorbent doses, and initial feed concentration and decreases with the increase in pH of the medium. The desorption of metal ions were carried out using 1N HCl and 0.5N H₂SO_4. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Comparative study of the determination of platinum by extraction with Cyanex 923 and Cyanex 471X from bromide media

The extraction equilibrium study of Pt(IV) was carried out with Cyanex 923 and Cyanex 471X in toluene from hydrobromic acid media to investigate their extraction capacity, since they have different donor atoms, ‘O’ and ‘S’. Their distribution equilibria were studied as a function of extractant concentration, diluents, hydrobromic acid concentration and the effect of temperature on extraction. Pt(IV) was quantitatively extracted with 0.1 mol dm^?3 Cyanex 923 in toluene from 5.0–8.0 mol dm^?3 HBr media and was stripped with 4.0 mol dm^?3 perchloric acid. However it was also quantitatively extracted with 0.1 mol dm^?3 Cyanex 471X (with 0.1 mol dm^?3SnCl₂) in toluene from 6.0–8.0 mol dm^?3 HBr media and was stripped with 1.0 mol dm^?3 stabilized sodium thiosulfate solution at pH 9.0. The slope analysis method indicated metal complex species of 1:1 for Pt(IV) with Cyanex 923 and Cyanex 471X in toluene from HBr media. These methods were successfully applied to the analysis of platinum in real samples. © 2001 Society of Chemical Industry     

Zn-Enhanced Asp-Rich Antimicrobial Peptides: N-Terminal Coordination by Zn(II) and Cu(II), Which Distinguishes Cu(II) Binding to Different Peptides

The antimicrobial activity of surfactant-associated anionic peptides (SAAPs), which are isolated from the ovine pulmonary surfactant and are selective against the ovine pathogen Mannheimia haemolytica, is strongly enhanced in the presence of Zn(II) ions. Both calorimetry and ITC measurements show that the unique Asp-only peptide SAAP3 (DDDDDDD) and its analogs SAAP2 (GDDDDDD) and SAAP6 (GADDDDD) have a similar micromolar affinity for Zn(II), which binds to the N-terminal amine and Asp carboxylates in a net entropically-driven process. All three peptides also bind Cu(II) with a net entropically-driven process but with higher affinity than they bind Zn(II) and coordination that involves the N-terminal amine and deprotonated amides as the pH increases. The parent SAAP3 binds Cu(II) with the highest affinity; however, as shown with potentiometry and absorption, CD and EPR spectroscopy, Asp residues in the first and/or second positions distinguish Cu(II) binding to SAAP3 and SAAP2 from their binding to SAAP6, decreasing the Cu(II) Lewis acidity and suppressing its square planar amide coordination by two pH units. We also show that these metal ions do not stabilize a membrane disrupting ability nor do they induce the antimicrobial activity of these peptides against a panel of human pathogens.     

Electrical properties of Cu(II) and Ni(II): N-salicylidene polymethacrylic acid hydrazide complexes

Different types of chelated polymer complexes have been synthesized to obtain improved electrical properties. Compact discs from powders of the chelated polymers were prepared and heated in a specially designed holder. Electrical conductivity and dielectric constant of Cu(II) and Ni(II): N-salicylidene polymethacrylic acid hydrazide samples were measured at a fixed frequency (1600 Hz) throughout the temperature range 25-150°C. The AC conductivity as well as dielectric measurements showed maxima at 85°C. The water molecules which were trapped in the polymer matrix are believed to play the main role in conduction and dielectric behaviour of the polymeric material. From the AC conductance and dielectric constant measurements, the dielectric losses of these polymeric materials were calculated as a function of temperature.     

Separation and concentration processes of solutions of Co(II), Ni(II), Cr(III), Fe(III) and Mn(II) by extraction with toluene-dissolved rosin

The extraction and stripping of Co(II), Ni(II), Cr(III) and Fe(III) from aqueous solutions by rosin dissolved in toluene has been investigated. Results obtained show that rosin is better extractant than abietic or n-lauric acids under comparable conditions. From these results, and the data of Mn(II) solvent extraction studied previously under the same conditions, a separation and concentration process for these five cations in aqueous solutions has been designed. Saturated solutions of Fe(III), Cr(III), Mn(II) and finally Co(II) and Ni(II) have been obtained successively by extraction and stripping, by addition of ammonium hydroxide to obtain the appropriate pH value, and by modifying adequately the organic phase/aqueous phase volume ratio.     

The Potential Antimicrobial Action of Human Mucin 7 15-Mer Peptide and Its Metal Complexes

Mucin 7 (encoded byMUC7) is a human salivary protein that has a role in the natural immune system. Fragments of mucin 7 exhibit antimicrobial activity against bacteria and yeast. Although the antimicrobial properties of peptides have been known and studied for decades, the exact mechanism of action of antimicrobial peptides (AMPs) is still unclear. It is known that some AMPs require divalent metal ions to activate their activity. Herein, we investigated three 15-mer MUC7 peptides, one of which (mother peptide, sequence, L3) is a synthetic analog of a fragment naturally excised from MUC7 (with His3, His8, and His 14) and its two structural analogs, containing only two histidine residues, His3, His13 and His8, His13 (L2 and L1, respectively). Since there is a correlation between lipophilicity, the presence of metal ions (such as Cu(II) and Zn(II)) and antimicrobial activity of AMP, antimicrobial properties of the studied peptides, as well as their complexes with Cu(II) and Zn(II) ions, were tested for activity against Gram-positive (Enterococcus faecalis, Staphylococcus epidermidis) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria and fungi (Candida albicans). The results were correlated with their lipophilicity. Coordination and thermodynamic studies (potentiometry, UV-Vis, CD) revealed the formation of mainly mononuclear complexes in solution for all studied systems with different stability in the physiological pH range.     

Biogenic Separation,Accumulation and Cellular Distribution of Cu,Co, and Ni in Medicago sativa under Idealized Conditions

The limits of uptake of Co, Ni, and Cu by the common metallophyte, Medicago sativa, were assessed using hydroponic growth and metal uptake experiments. The influence of the growth substrate metal concentration (500 and 1000 ppm) and exposure time, i.e., the time plants were exposed to the metal solution (24, 48, or 72 h) was investigated. The combined roots and shoots of Medicago sativa accumulated up to 2.2 wt-% Co, 2.0 wt-% Ni, and 3.5 wt-% Cu, when exposed to aqueous solutions containing 1000 ppm Co for 48 h, 1000 ppm Ni for 72 h, and 1000 ppm Cu for 72 h, respectively. The distribution of the sequestered metals was assessed using proton induced that X-ray emission spectroscopy (μ-PIXE), which indicated that translocation mechanism was most likely xylem loading. However, the rate of translocation of the metal from the roots to the plant stem was different for each metal, suggesting differing mechanisms for each. Collectively, these results suggest the separation and removal of the heavy metals Cu, Co, and Ni from contaminated substrates using Medicago sativa is a viable technology.     

Removal of Cadmium(II) Ions from Chloride Solutions by Cyanex 301 and Cyanex 302

The main goal of this work was to study and compare the extraction of cadmium(II) ions by the two organophosphorous extractants: Cyanex 301 and Cyanex 302. The effect of different variables influencing the extraction of cadmium(II) ions such as the concentration of acid or metal ion and type of extractant has been investigated. Obtained results from the extraction process were compared with the FT-IR spectra. Results of spectrophotometric analysis confirm the observations of the extraction process, for example, the negative effect of hydrochloric acid on cadmium extraction by Cyanex 302.     

Mass Transfer and Immobilized Organic Phase Instability Studies for Cobalt(II)–Nickel(II) Separation by PEHFSD

Pseudo-emulsion-based hollow-fiber strip dispersion (PEHFSD) technique was examined as an alternative to solvent extraction for simultaneous separation and concentration of cobalt(II)–nickel(II) mixture using Cyanex-272 as the extractant. Experiments were carried out by continuous recirculation of the feed and pseudo-emulsion phases through a hollow-fiber module. The separation factor increased rapidly after 60 min of operation. The maximum value after 120 min of operation was ～128 (pH = 6.5) for the operating conditions studied. The mass transfer resistance from the extraction reaction appeared to be dominant. The results of mathematical modeling of the mass transfer process indicated that higher separation factor and extraction rate can be achieved using PEHFSD in comparison to solvent extraction. Mixing of the stripping and the feed solution was observed at high dispersed phase volume fraction in the pseudo-emulsion and low flow rate of this phase. The maximum value of backtransport flux from the stripping phase due to mixing was estimated to be approximately two orders lower than the initial extraction rates.