A New Sorbent for Selective Separation of Metal: Polyethylenimine Methylenephosphonic Acid

Abstract

A new sorbent, the polyethylenimine methylenephosphonic acid (PEIMPA), was synthesized from commercially available polyethylenimine. After characterization by (¹H, ¹³C, ³¹P) NMR, elementary analysis, UV/VIS and FTIR, the new ion exchange polymer PEIMPA has been investigated in liquid – solid extraction of a mixture of Cd(II), Co(II), Cu(II), Fe(III), Ni(II), Pb(II), and Zn(II) cations from a mineral residue of zinc ore dissolved in nitric acid. The selectivity of this polymer was studied as a function of pH. PEIMPA can sorb much higher amounts of Fe ion than Cd, Co, Cu, Ni, Pb, and Zn ions. The recovery of Fe(III) is almost quantitative. Because of this remarkable affinity, the PEIMPA resin has the potential for application in several fields. Further studies of the polymer are in progress.     

Analytical Applications of Mixed Ligand Complexes. II. Separation-Gravimetric Determination of Cu(II) as Its Mixed Ligand Complex with 1,10-Phenanthroline and p-Cresotic Acid

Abstract

A method is presented for the gravimetric determination of Cu(II) followed by its separation from Ni(II), Co(II), Mn(II), and other anions and cations by precipitating it as its mixed ligand complex with 1,10-phenanthroline and p-cresotic acid (5-methylsalicylic acid). The precipitate is equivalent to 0.184 times its weight of copper. The method has potential for use in the large-scale separation of copper.     

A Novel Copper(II)–Hydrogen Oxalate Coordination Polymer Showing a New Coordination Mode

A novel Cu(II) coordination polymer of general empirical formula {[Cu(μ-HC₂O₄)₂(H₂O)₂][Cu(HC₂O₄)₂]∙6H₂O} _n (1) has been synthesized and characterized by single-crystal X-ray diffraction technique. The complex (1) crystallizes in the triclinic form with P-1 space group. It is quite surprising that single crystal X-ray analysis of 1 illustrates the presence of hydrogen oxalate ligand in the coordination environment of Cu(II) ion. Because oxalate is not present in the starting reaction mixture, it may be derived from the reduction of squarate ligand. In 1, Cu(II) ions exhibit two different coordination environments, forming a distorted octahedral geometry. The Cu1 is coordinated with six oxygen atoms from two bidentate HC₂O₄ ⁻ and two aqua ligands, while Cu2 is coordinated with six oxygen atoms from four HC₂O₄ ⁻ ligands. The HC₂O₄ ⁻ ligand acts in two different coordination modes, as a bidentate and an unprecedented tridentate bridging coordination mode.     

Batch and Column Adsorption of Cu(II) on Unmodified and Oxidized Coir

Abstract

The potential of coir, a low cost lignocellulosic material, was assessed for the removal of Cu(II) ion from aqueous solutions of copper sulphate. The coir fiber was also modified by an oxidative treatment, whereby the maximum uptake of Cu(II) increased to 6.99 mg/g as compared to 2.54 mg/g for the unmodified coir. A Langmuir type of adsorption was followed by oxidized coir fiber. A second order rate equation was observed for the Cu(II) uptake. The lowering of pH adversely affects adsorption on both the materials. Almost complete desorption of the loaded Cu(II) was possible using 0.25 N hydrochloric acid. The materials retained the adsorptive capacity up to three cycles when an intermediate regeneration step was given with dilute sodium hydroxide solution. In a fixed column packed with oxidized coir fibers, it was observed that the breakthrough time decreased with an increase in inlet Cu(II) concentration. The desorption level in the fixed bed column was around 90% and the column was regenerated and used up to eight cycles. The fixed bed column packed with oxidized coir was used to remove Cu(II) from an electrochemical industrial effluent. An ion exchange mechanism has been proposed for uptake of Cu(II) on the oxidized coir fiber.     

Tilapia scales: characterization and study of Cu(II) removal by ion exchange with Ca(II)

ABSTRACT

A biosorbent material based on tilapia scales for the removal of Cu(II) ions was investigated. Modifications in the biosorbent caused by retention of Cu(II) and by the pH effect were evaluated separately in order to comprehend how the removal process occurs. For that, a physico-chemical characterization of the scales was performed before and after the Cu(II) removal. The results obtained from the characterization and biosorption tests led to the conclusion that the Ca–Cu ions exchange was responsible for purifying the solution. Furthermore, the tilapia scales were efficient, removing 95% of Cu(II) with 1 g of adsorbent (surface area ≈ 3 m²).     

Precipitate Flotation Studies with Monolauryl Phosphate and Monolauryldithiocarbamate

Abstract

Monolauryl phosphate has been employed for the removal of copper(II), manganese(II), and zinc(II) by foam flotation at various pH's and ionic strengths. Good removals of all three metal ions were obtained in the basic pH range and in the presence of up to 0.2 M sulfate. Coprecipitation of Zn(II) with ferric hydroxide was essential to attain good removal of Zn(II). The removal of Cu(II) was also good from solutions containing oxalate, silicate, phosphate, and metaphosphate; however, the presence of EDTA hinders the removal of Cu(II). The potential of lauryldithiocarbamate as a chelating surfactant for the removal of Cu(II) was explored at various pH's and in the presence of various anions. We conclude that lauryldithiocarbamate is a weak chelating agent, unable to compete efficiently for Cu(II) with anions such as CO₃ ^2?, HPO₄ ^2?, SiO₃ ^2?, and EDTA. The relatively rapid decomposition of lauryldithiocarbamate in solution coupled with its weakness as a chelating surfactant make it unsuitable for the removal of Cu(II) by foam flotation.     

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.     

ADSORPTION AND SEPARATION BEHAVIOR OF COBALT,NICKEL, AND COPPER IN NITRITE MEDIUM BY ANION EXCHANGER

ABSTRACT

To investigate the possibility of separation of metal ions in nitrite medium by anion exchange, adsorption and elution behavior of the three typical transition metals of Co(II), Ni(II) and Cu(II) in nitrite solution with a commercial anion exchanger, Amberlite IRA-900 and a novel silica-based anion exchanger, AR-01 with fine particle size has been studied. Furthermore, the separation behavior of these metal ions in nitrite solution was demonstrated by anion exchange chromatography. Co(II) and Cu(II) showed strong adsorption onto the anion exchangers in nitrite solution, while the adsorption of Ni(II) was very weak. The adsorption is considered to result from the formation of anionic nitro-complexes. Complete separation of Co(II) from Ni(II), and Cu(II) from Ni(II) was achieved in column experiments with a dilute nitric acid as eluent. Compared to IRA-900, AR-01 showed significantly faster adsorption and elution kinetics.     

Copper(II) Extraction from Phosphoric Acid Media by 5‐Dodecylsalicylaldoxime (LIX 622)

Abstract

The extraction of Cu(II) from phosphoric acid media (0.4–7.3 M) by the commercial reagent LIX 622 in toluene has been studied. Experimental results have been treated numerically and the formation in the organic phase of the complex CuR₂, HR being 5‐dodecylsalicylaldoxime, has been proposed. Values of the conditional extraction constants, which increase with the phosphoric acid concentration, are given. Organic extracts have been analyzed by EPR spectroscopy. The presence of a square planar complex of Cu(II) has been deduced confirming the stoichiometry CuR₂.     

Kinetic and Thermodynamic Separation of Cu(II) and Fe(III) by Liquid-Liquid Extraction with a β-Hydroxy-oxime in Toluene

Abstract

A quantitative study of the thermodynamic and kinetic separation of Cu(II) and Fe(III) by liquid-liquid extraction with toluene solutions of the oxime 2-hydroxy-5-t-octyl (acetophenone oxime) has been conducted. On the basis of the stoichiometry, equilibrium constants, rate laws and rate constants of the extraction reactions of Cu(II) and Fe(III) an equation has been derived which describes how the separation of Cu from Fe varies with the chemical composition of the system, the hydrodynamics of the extracting apparatus and the contact time between the aqueous and the organic phases. Our results show that separations which are not feasible thermodynamically are possible when the contact time between the two phases is kept much shorter than that required to reach equilibrium.     

Solvent extraction of copper ions by 3-substituted derivatives of β-diketones

ABSTRACT

Two derivatives of acetylacetone (acac, 1), namely 3-butyl-acac (2) and 3-allyl-acac (3), were synthesized. A liquid–liquid partition and spectrophotometric methods were used to examine the process of complexes formation of all ligands with Cu(II) ions. It has been shown that 2 and 3 were forming two very stable complexes of ML and ML₂ type. The absorption spectra proved that the extraction of copper was simplified because flat-square complexes were formed. The high values of partition ratios of two types of complexes confirm this fact. The rate of extraction of Cu(II) complexes decreases in the order 3 > 2 > 1.     

Adsorbing Colloid Flotation of Cu(II) with a Chelating Surfactant

Abstract

Cu(II) is effectively removed from synthetic mixtures by dodecylamine-N,N-diacetic acid with Fe(OH)₃ and a carrier foam. The effects of pH and ionic strength on the separation are ascertained. Cu(II) is effectively floated at much higher ionic strengths with dodecylamine-N,N-diacetic acid than with nonchelating surfactants such as sodium lauryl sulfate.     

Fast removal of Pb(II) and Cu(II) from contaminated water by groundwater treatment waste: impact of sorbent composition

ABSTRACT

A non-hazardous groundwater treatment waste (GWTW) was examined as a low-cost sorbent for Pb(II) and Cu(II) ions. The content of the dominant elements in GWTW was as follows: 78% Fe₂O₃, 7.4% P₂O₅, 7.4% CaO and 5.2% SiO₂. The removal of Pb(II) and Cu(II) was fast, and more than 67–95% of ions were accumulated by GWTW during the first 3 min. The sorption capacity of GWTW depends on solution pH, concentration and temperature. Equilibrium data fitted well with Langmuir–Freundlich and Langmuir-partition models. The inherently formed nano-adsorbent could be utilized for the treatment of water contaminated with Pb(II) and Cu(II) ions.     

Recovery and Concentration of Metal Ions. II Multimembrane Hybrid System

Abstract

The multimembrane hybrid system (MHS) has been developed and used for the transportation and separation of divalent metal ions from multicomponent solutions. The system consists of three membranes in series

ion-exchange membrane | liquid membrane | ion-exchange membrane

The experiments were performed with liquid membranes composed of di(2-ethylhexyl)phosphoric acid in kerosene and Nafion-120 perfluorosulfonic acid polymer membranes. The fluxes and separation characteristics have been determined for MHS separating a solution of Zn(II), Mn(II), Cu(II), and Ni(II) sulfates as the feed phase, and the strip phase containing sulfuric acid. The results of competitive permeation experiments have shown the selectivity order Zn(II) > Mn(II) > Cu(II) ? Co(II), Ni(II). High separation coefficients were found for Zn(II), Cu(II), and Mn(II) compared to Ni(II) and Co(II).     

Adsorption Behavior of Iminodiacetic Acid Type of Chelating Gel Prepared from Waste Paper

Abstract

Adsorption gel was prepared from waste recycled paper by immobilizing iminodiacetic acid (IDA) functional group by chemical modification. The gel exhibited good adsorption behavior for a number of metal ions viz. Cu(II), Pb(II), Fe(III), Ni(II), Cd(II), and Co(II) at acidic pH. The order of selectivity was found to be as follows: Cu(II)>Pb(II)>Fe(III)>Ni(II)～Cd(II)～Co(II). From the adsorption isotherms, the maximum adsorption capacity of the gel for both Cu(II) and Pb(II) was found to be 0.47 mol/kg whereas that for Cd(II) was 0.24 mol/kg. A continuous flow experiment for Cd(II) showed that the gel can be useful for pre‐concentration and complete removal of Cd(II) from aqueous solution.     

SOLVENT IMPREGNATED RESINS CONTAINING DI(2-ETHYL-HEXYL)PHOSPHORIC ACID.II. STUDY OF THE DISTRIBUTION EQUILIBRIA OF Zn(II), Cu(II) AND Cd(II).

ABSTRACT

The extraction of Zn(II), Cu(II) and Cd(II) from nitrate solutions at 0.1 M ionic strength by impregnated resins containing di(2-ethylhexyl)phosphoric acid has been studied at 25 °C.

The distribution coefficient was determined as a function of both pH and extractant concentration in the resin phase. The data were analyzed graphically using the slope analysis method, and numerically using the program LETAGROP-DISTR. The composition of the extracted species in the resin phase has been determined.

Analysis of the results showed that the extraction of these metal ions can be explained assuming the formation of metal complexes in the resin phase with a general composition ML₂(HL) _q where q takes different values depending on the metal. An extraction reaction is proposed and the extraction constants of these species are given.

Finally, a comparison between the extraction of Zn(II), Cu(II) and Cd(II) by di(2-ethylhexyl)phosphoric acid into Amberlite XAD2 and the extraction using organic solvents has been made.     

A Facile One-pot Synthesis of Fluorescent Hyperbranched Polyesteramine (PEA) Architecture

Summary: One pot synthesis of hyperbranched polyester amine (PEA) 1 (G2) with peripherally appended naphthyl units has been achieved and found to display strong fluorescence signaling towards Co(II) and Cu(II) ions.     

Homogenous and Heterogeneous Catalytic Activity of Azo-Linked Schiff Base Complexes of Mn(II), Cu(II) and Co(II)

Abstract  

Azo linked Schiff-base[L] complexes of Mn(II)(1), Cu(II)(2) and Co(II)(3) obtained by template method, in the reaction of 4-(benzeneazo) salicylaldehyde with 1,2-propanediamine in the present of metal acetate, respectively. Complexes are used as catalyst for oxidation of cyclohexene with tert-butylhydroperoxide (TBHP); oxidation of cyclohexene catalyzed by these complexes gave 2-cyclohexene-1-one and 2-cyclohexene-1-ol as major products. Conversion of cyclohexene achieved was 95–100% with (1), (2) and (3), with selectivity of 57, 92 and 100% for 2-cyclohexene-1-one, respectively. The encapsulated Cu(II) complex (Cu–NaY) catalyzes the oxidation of cyclohexene using TBHP as oxidant in good yield. (Cu–NaY) under optimized reaction condition gave three reaction products. A maximum of 100% conversion of cyclohexene has been achieved where selectivity of 2-cyclohexene-1-one was 83%.     

The Influence of Alkyl Chain Length in 1,2-Dialkylimidazoles on the Extraction Capacity and Structure of Their Copper(II) Complexes

Abstract

Formation of Cu(II) complexes of 1,2-dialkylmidazoles (where 1-alkyl = ethyl, propyl, butyl, pentyl, and hexyl, and 2-alkyl = propyl, butyl, and pentyl) has been studied using the liquid-liquid partition method, at 25°C and at a fixed ionic strength of the aqueous phase (I = 0.5; (HL)NO₃, KNO₃). The complexes were extracted with 2-ethyl-1-hexanol, and chloroform. The length of the 1-alkyl, and 2-alkyl groups, and the solvent nature have been shown to influence the extraction process. Extraction curves (log D_M vs. pH) are displaced towards lower pH with increasing chain length of the 1-alkyl and 2-alkyl substituents. Stability constants of the complexes in aqueous solution as well as their partition constants between the aqueous and organic phase were determined. The stability of the Cu(II) complexes increased with increasing 1-alkyl chain length. The stability constants were comparable with β _n values for the Cu(II) complexes of 1-alkyl-2-ethylimidazoles, but smaller than those of the Cu(II) – 1-alkylimidazole counterparts. The length of the 2-alkyl substituent has been found to affect both the pH_1/2 values and the partition constants of the complexes. The partition constants P₁ are small for all of the 1,2-dialkylimidazole complexes with Cu(II), whereas P₂ and P₃ are high and they increase with elongation of the 1-alkyl chain owing to a decrease in the co-ordination number of Cu(II), probably from 6 to 4 at the second and third complexation step. This change is likely to produce square coplanar species, readily extractable with organic solvent. This finding offers the possibility of extraction of the Cu(II) ions from a mixture cations.