Sorption of Gold(I) from Ammoniacal Solutions into ∝‐Zirconium(IV) Bismonohydrogenphosphate (∝‐Zrp) Intercalated with Butylamine

Studies on sorption of diammine Au(I) cationic complex from ammoniacal solutions of varying composition into pure and modified with butylamine α‐ZrP have been performed in the temperature change from 40 to 80°C. Experimental results have been discussed in terms of first order reaction kinetics. The activation energies of sorption of Au(I) into pure and modified α‐ZrP were found to be equal to 28 (± 3) and 84 (± 7) kJ?mol^?1, respectively. The effects of concentrations of ammonia, ammonium sulfate and Cu(II) were also examined. The kinetic parameters of sorption of tetraammine Cu(II) complex from ammoniacal solutions into modified α‐ZrP were also determined.     

Ultrafiltration of Aqueous Solutions of PVA‐Cu(II) Macromolecular Complex

Abstract

The hydrodynamic behavior of aqueous solutions of poly(vinyl alcohol) and poly(vinyl alcohol)–cupric complex and its effect on the performance in the concentration of the macromolecular cupric complex by ultrafiltration is considered in this study which implements various synthetic membranes in polyethersulfone. The polyelectrolyte–like behavior of poly(vinyl alcohol) is highlighted. This behavior disappears in the case of the macromolecular complex. The disappearance of the polyelectrolyte–like effect is explained by the modification of the macromolecular conformation induced by the formation of the complex which takes up a tightly packed conformation. The study of the effect of the variation of the pH and the ionic strength made it possible to observe that the increase of the pH is accompanied by the reduction of the medium viscosity and the increase of the flux through the ultrafilters and the increase of the ionic strength of the medium is accompanied by the increase of the thickness of the adsorbed solute layer. The study of the effect of the nature of the ionic species in solution on the hydrodynamic behavior of the aqueous solutions of the macrocomplex leads to the conclusion that the use of the cupric chloride salt, instead of the nitrate or the sulphate salts, in the preparation of the macrocomplex improves the hydrodynamic properties of the solution and enhances the performance of its treatment by means of the ultrafiltration process.     

Sorption of U(VI) onto Layered Double Hydroxides of Mg and Al with β-Cyclodextrin from Aqueous Solutions

Theoretical Foundations of Chemical Engineering - The possibility of removing U(VI) from aqueous solutions using layered double hydroxides of Mg and Al, which contain β-cyclodextrin...     

Heteronuclear Cu(II)–Mn(II)–Cu(II) Complex Constructed from Metallo-Ligand Through Carboxylate Oxygens: Coexistence of Water Hexamers

A heteronuclear complex of [Mn(H₂O)₄(CuL)₂]₂·4H₂O 1 (H₂L = 2-hydrogen benzaldehydeneglycylglycine) has been synthesized and characterized by IR spectra, TGA, and single crystal X-ray diffraction analysis. The molecule consists of one $\text{Mn}{(\text{H}_{2}\text{O})_{4}}^{2+}$ Mn(H₂O) ₄ ²⁺ group and two symmetric groups [CuL]^? which are connected by carboxylate oxygen atoms. A discrete water hexamer composed of a planar tetrameric water ring and two pendent water molecules acts as a ‘glue’ to assemble adjacent [CuL]^? into a two-dimensional structure.     

Removal of Copper (II) Ions from Aqueous Solutions using Na‐mordenite

Abstract

The potential to remove copper (II) ions from aqueous solutions using Na‐mordenite, a common zeolite mineral, was thoroughly investigated. The effects of relevant parameters solution pH, adsorbent dose, ionic strength, and temperature on copper (II) adsorption capacity were examined. The sorption data followed the Langmuir, Freundlich, and Dubinin‐Radushkevich (D‐R) isotherms. The maximum sorption capacity was found to be 10.69 mg/g at pH 6, initial concentration of 40 mg/dm³, and temperature of 40°C. Different thermodynamic parameters viz., changes in standard free energy (ΔG⁰), enthalpy (ΔH⁰), and entropy (ΔS⁰) have also been evaluated and the results show that the sorption process was spontaneous and endothermic in nature. The dynamics of the sorption process were studied and the values of rate constant of adsorption, rate constant of intraparticle diffusion were calculated. The activation energy (E_a) was found to be 11.25 kJ/mol in the present study, indicating a chemical sorption process involving weak interactions between sorbent and sorbate. The interaction between copper (II) ions and Na‐mordenite is mainly attributable to ion exchange. The sorption capacity increased with the increase of solution pH and the decrease of ionic strength and adsorbent dose. The Na‐mordenite can be used to separate copper (II) ions from aqueous solutions.     

Synthesis and Characterization of Mesostructured Silica Doped with Acyl‐Hydroxy‐Pyrazole Derivatives. Sorption Tests of Cu(II) and Eu(III)

Abstract

The synthesis and the characterization of mesostructured silica doped with acidic acyl‐hydroxy‐pyrazoles like extractants are described. The extractants have either a single chelating site, 1‐phenyl‐3‐methyl‐4‐stearoyl‐5‐hydroxy‐pyrazole (HPMSP), or two chelating sites, 1,12‐bis(1′‐phenyl‐3′‐methyl‐5′‐hydroxy‐4′‐pyrazolyl)‐dodecane‐1,12‐dione (HL‐10‐LH). The so‐called doped silicas were synthesized in basic medium according to a sol‐gel process beginning with the solubilization of the extractant in a micellar phase followed by the precipitation of silica around micelles. The chemical composition of the synthesized materials, especially the ligand content, was determined. High quantities of ligand loadings (up to 0.69 mol/kg) are reached. The materials obtained were characterized by X‐ray diffraction, laser granulometry, transmission and scanning electron microscopy and, after calcination, by nitrogen physisorption. Un‐doped silica is mesostructured, lamellar, and has high pore diameter as well as high specific surfaces. Doping induces the disorganization of the lamellar structure, the increase of the pore diameter, and a slight decrease of the specific surface. The capacities of extraction of Cu(II) and Eu(III) by the doped materials and the corresponding extraction rate were measured: high values are reached.     

Use of α-Cellulose Coated with Titanium(IV) Oxide in Separation of CrVI

Abstract

α-Cellulose reacted with TiCl₄ was hydrolyzed to obtain a TiO₂ coating on the biopolymer surface. Cr^VI in a concentration range between 10 and 50 ppb was separated from Cr^III using a column packed with this material. The presence of other ions such as Cu^II, Mn^II, Hg^II, and Fe^III, and the anions VO^3- ₃, MoO^2- ₄, PO^3- ₄, and SO^2- ₄, did not interfere significantly in the separation process.     

Thin‐Layer Chromatography of Cu(II), Co(II) and Ni(II)

Abstract

The chromatographic behavior of some heavy metals on thin layer of silica gel was studied. The effect of polarity of mixed developing agent systems on the R_f values of metal complexes was investigated. The linear dependence between the R_f values and the polarity of developing agents was deduced and a series of good separations of Cu(II),Co(II) and Ni(II) were obtained successfully. This method was applied to separate Cu(II) and Ni(II) in a real sample.     

New experimental insights into the formation of unexpected water-soluble Eu(III)–Cu(II) 15-metallacrown-5 compound with acetate

Despite a large amount of systematic structural studies of the affinity of copper–lanthanide 15–metallacrown-5 complexes derived from α-aminohydroxamic acids for various organic carboxylates, the acetate ion has not been previously observed to bind to the Ln^3 +[15-MC-5]. The first Eu(OOCCH₃)[15-MC_Cu(II)Glyha-5](NO₃)₂ metallacrown with acetate coordinating to the central lanthanide ion has been prepared in 75% yield. According to the X-ray diffraction study all bond distances and angles in this complex are in the ranges typical for metallacrowns. However, due to a specific network of hydrogen bonds the coordination of the acetate anion to the Eu[15-MC_Cu(II)Glyha-5]^3 + cation leads to a greater distortion of the metallacrown cation from planarity as compared to the known nitrate analogues.     

Extraction of Neptunium (IV) Ions into 30% Tri‐Butyl Phosphate from Nitric Acid

The distribution of Np(IV) between 0.08–4.5 M HNO_3(aq,eqm) and ～30% tributyl phosphate has been modelled, accounting for the formation of 1:1 and 1:2 nitrate complexes and Np(IV) hydrolysis in the aqueous phase and the extraction of Np(NO₃)₄(TBP)₂ into TBP. The potential formation and extraction of NpOH(NO₃)₃(TBP)₂ and Np(NO₃)₄(TBP)₂.HNO₃ species, including spectroscopic evidence, and oxidations of Np(IV) to Np(V) and Np(VI) in the solvent phase have also been considered. The model highlights some key gaps in the available thermodynamic data.     

Copolymerization of carbon monoxide and styrene with the Nd(III)–Cu(II) catalyst

In this article, the linear alternating copolymer of carbon monoxide and styrene was obtained using the Nd(III)–Cu(II) catalyst. It was found that the introducing order of the catalyst components can affect the catalytic activity, and the pre-prepared catalyst had higher catalytic activity than the in situ catalyst. The promoting effect of copper acetate on the catalytic activity was also investigated. The structure of the copolymer was characterized by means of IR, ¹H-NMR, ¹³C-NMR, WXRD, and EA methods. The thermal decomposition properties were checked by the way of TGA. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 8–13, 2001     

Grafting of High α-Cellulose Pulp Extracted from Sunflower Stalks for Removal of Hg (II) from Aqueous Solution

Dissolving pulp containing 95.5% α-cellulose was extracted from sunflower stalks. The pulped sunflower stalks (PSFS) were used as starting material for grafting with acrylamide (Aam). All factors affecting the grafting reaction were examined. These factors include liquor ratio (LR), ceric ammonium nitrate (CAN) concentration as a catalyst, Aam concentration, as well as reaction time and temperature. The grafted PSFS (GPSFS) samples were characterized by estimation of nitrogen %. The GPSFS was utilized as adsorbent material to remove Hg (II) ions from aqueous solutions. All factors affecting adsorption process were examined. These factors include pH, adsorbent concentration, temperature, and agitation time. The adsorption data show that the maximum adsorption capacity, q_e, of Hg (II) onto GPSFS is 625 mg/g. The adsorption data also showed that the adsorption of Hg (II) onto GPSFS obeys Langmuir and Freundlich isotherms.     

Removal of mercaptans from light oil cuts using Cu(II)–Y type Zeolite

In this paper, the removal of mercaptans (also known as Thiols) from two types of oil cuts, L-SRG and L-Naphtha, from Isfahan Refinery (Iran) was investigated by using synthesized Cu(II)–Y type zeolite in a batch system. The results were compared with those obtained over parent Na–Y zeolite. The effects of three parameters i.e. ion-exchange level, the mass of zeolite per volume of oil cut, and contact time on the removal of mercaptan (RSH) were investigated at ambient temperature. The numbers of experiments were minimized by using Taguchi method. In this regard, four levels making orthogonal array L₁₆, were selected for each parameter. It was observed that the removal of sulfur was extremely influenced by selected parameters.     

Removal of Cr(VI) Oxy‐anions from Aqueous Solution by Sorption into Poly(Acrylamide‐Co‐Maleic Acid) Hydrogels

Abstract

The dynamic removal of hexavalent chromiuim by poly(acrylamide‐co‐maleic acid) hydrogels was studied by a batch equilibrium technique at 35°C. Various kinetic and adsorption parameters such as rate constant for sorption, intraparticle diffusion rate constant, Langmuir constant, and adsorption capacity have been evaluated. The sorption process follows the Langmuir‐type behavior and extent of sorption of Cr(VI) ions depends upon the composition of co‐polymeric gels, presence of other ions in the solution, and temperature of the system. Relatively higher temperature favors the sorption process. The activation energy was found to be ?20.369 kJ mol^?1. Finally, various thermodynamic parameters have also been calculated to elucidate the mechanism involved in the sorption process. The positive enthalpy change indicates the endothermic nature of the process. The presence of fluoride ions causes a decrease in the degree of sorption of Cr(VI). Finally, the sorption of Cr(VI) into the copolymeric sorbent has been explained on the basis of coordination between electron rich O and N atoms of sorbent molecules and the Cr(III) molecules. Moreover, H‐bonding interactions also seem to contribute to the sorption process.     

Effect of Alkanediyl-α,ω-Type Cationic Dimeric (Gemini) Surfactants on the Reaction Rate of Ninhydrin with [Cu(II)-Gly-Tyr]+ Complex

The effect of gemini (16‐s‐16, s = 4, 5, 6) surfactants on the reaction rate of ninhydrin with [Cu(II)‐Gly‐Tyr]⁺ complex was determined using a spectrophotometric technique. The ninhydrin concentration was kept in excess in order to maintain pseudo‐first‐order conditions. The reaction followed irreversible first‐ and fractional‐order kinetics with respect to [Cu(II)‐Gly‐Tyr]⁺ and [ninhydrin], respectively. It is found that gemini surfactants effectively catalyze the reaction. The rate constants (k_ψ) first increase and then become relatively constant with increasing gemini surfactant concentration similar to conventional cetyltrimethylammonium bromide. At higher gemini surfactant concentration a third region of increasing k_ψ is observed. The unusual third region is ascribed to changes in micellar morphology. The kinetic data has been analyzed using a micellar pseudo‐phase model.     

Studying the Sorption Processes of Rare-Earth Elements with the Use of Sulfocationites from Nitric Acid–Phosphoric Acid Solutions in a Pulsed Column

Theoretical Foundations of Chemical Engineering - The kinetics of sorption and regeneration from industrial nitric acid–phosphoric acid solutions with the use of ion-exchange resins like KU-2...     

Dicyanamido–metal(II) complexes. Part 3: Hydrolysis of the dicyanamide into amidocyanamide during its interaction with Cu(II) perchlorate and 2-pyridylcarbonyl-N,N-bis(2-pyridylmethyl)amine

The reaction of Cu(ClO₄)₂, 2-pyridylcarbonyl-N,N-bis(2-pyridylmethyl)amine (DPA-CO-py) and sodium dicyanamide (Nadca) in aqueous medium led to the isolation of three complexes: {[Cu(DPA)(μ_1,5-dca)]ClO₄}_n (1), [Cu₂(pic)₂(μ_1,3-H₂NCO–N–CN)₂(H₂O)₂] · 2H₂O (2) and Cu(pic)₂ · H₂O (3). The Cu²⁺ ion, during its complex formation with DPA-CO-py and dca not only assisted the hydrolysis of DPA-CO-py to the corresponding di(2-methylpyridyl)amine (DPA) and picolinic acid (Hpic) but also resulted in partial hydrolysis of one of the two nitrile groups of the dicyanamide, NC–N–CN^? (dca) to amidocynamide, H₂NCO–NH–CN. The complexes were structurally characterized and the single X-ray structures for 1 and 2 reveal their identity. Complex 1 forms a 1D polymeric chain with the dca acting as a μ_1,5-bridging ligand via the terminal nitrile nitrogen atoms. A distorted SP geometry around the Cu²⁺ centers was achieved by the three N-atoms of the DPA and by the two nitrile groups of the bridging dca ligands. Complex 2 consists of a dimeric unit with CuN₃O₂ chromophore in coordination polyhedron that has a distorted SP geometry. The amidocyanamide ion, H₂NCO–N–CN^? acts as bis(monodentate) μ_1,3-bridging ligand via the central amido and terminal nitrile nitrogen atoms whereas the picolinate anion forms a six-membered chelate ring through its pyridyl nitrogen and an oxygen atom of the carboxylate group, and the aqua water occupies the apical position of the structure. Complex 1 exhibits very weak antiferromagnetic coupling (J = ?0.31 cm^?1) whereas 2 shows a significant antiferromagnetic interaction between the two copper centers (J = ?13.6 cm^?1).     

Poly (N-2-aminoethylacrylamide) grafted polystyrene–Cu (II) complex catalyzed conversion of aldehydes into primary amides in water

Poly (N-2-aminoethylacrylamide) grafted polystyrene–Cu (II) complex was synthesized and characterized by techniques such as FTIR spectroscopy, XRD, SEM–EDX, TGA and ICP-AES analysis. The catalyst exhibits an excellent catalytic activity for the conversion of various aldehydes to corresponding amides in water. Also, the catalyst could be recovered and reused five times without any significant loss in its activity.     

Syntheses,magnetic properties,and reactivity of dinuclear oxovanadium (IV) and copper (II) complexes with (μ-diphenylphosphinato)-bridges

Novel dinuclear oxovanadium (IV) complexes having the formula [(VO)₂(dpp)₃(bpy)₂]NO₃·2H₂O (1), [(VO)₂(dpp)₃(phen)₂]-NO₃·H₂O (2), [(VO)₂(bmp)₃(bpy)₂]NO₃·H₂O (3), and [(VO)₂(bmp)₃(phen)₂]NO₃·H₂O (4), and copper (II) complexes having the formula [Cu₂(bmp)₂(phen)₂](NO₃)₂·MeOH·H₂O (5), and [Cu₂(bmp)₂(bpy)₂](NO₃)₂ (6) (where Hdpp=diphenylphosphinic acid, Hbmp=bis(4-methoxyphenyl)phosphinic acid, bpy=2,2^′-bipyridine, and phen=1,10-phenanthroline) with (μ-phosphinato)-bridges, 1–6, have been prepared and characterized. Crystal structure of complex 2 reveals that two vanadium ions are linked by tris(μ-phosphinato)-bridges. The magnetic susceptibility data for 1–3, and 6 conform to the usual dimer equation with −2J values of 16–24 cm⁻¹, indicating a weak antiferromagnetic interaction between vanadium(IV) ions.The oxidation of cinnamyl alcohol was studied using complexes 1–6 as catalyst and molecular oxygen as an oxidant. In the presence of complex 3 as a catalyst, cinnamyl alcohol was oxidized to cinnamaldehyde 61% yield in 7 h. Consequently, complex 3 activates oxygen, and then alcohol was quite efficiently oxidized by activated oxygen.