Extraction of Copper(II) with N′,N′-Dialkylhydrazides of Benzoic and Phenylacetic Acids

This article is concerned with the study of the extraction of Cu(II), Co(II), Ni(II), and Zn(II) with N′,N′-dialkylhydrazides of benzoic and phenylacetic acids. The applied reagents are able to extract Cu(II) from ammoniac media efficiently. The influence of the length and structure of alkyl chains on the extraction of Cu(II) has been analyzed. It is shown that N′,N′-dibytil- and N′,N′-dihexylhydrazides of benzoic acid exhibit the most promise for extracting Cu(II) from ammoniac media, and N′,N′-dihexylhydrazide of phenylacetic acid as an extractant is worse than the analogous benzoic acid derivative. Copper stripping has been studied for various concentrations of H₂SO₄, and the copper extraction constants have been calculated. The data obtained indicate that the degree of Cu(II) extraction decreases with increasing concentration of ammonium salts.     

Some lanthanide (III) complexes of (S,S)-(+)-2,3-dimethoxyl-N,N′-dimethyl-1,4-diaminobutane

Four new optically active complexes of the composition LnL₃Cl₃ (where, L=(S,S)-(+)-2,3-dimethoxyl-N,N^′-dimethyl-1,4-diaminobutane, Ln=La³⁺, Sm³⁺, Pr³⁺ and Nd³⁺) were prepared and characterized on the basis of their chemical analyses, molar conductance, magnetic properties, CD, XPS, visible and IR spectra. It is found that the complexes behave as non-electrolytes in DMSO and in methanol solution and possess the stoichiometric ratio of Ln:C:N:O:Cl =1.1:24.0:6.1:6.0:3.1 which is consistent with the analyses data. The magnetic moments of the complexes show little deviation from the Van Vleck values, indicating that 4f electrons do not participate in bond formation in these chelates. The thermal analysis revealed that all the complexes are anhydrous. Their dominant conformers were determined from CD spectra. A nine-coordinated model was proposed for these complexes.     

Synthesis and Thermal Decomposition Studies of Silicon (IV) Compounds with N,N’-Bis(Salicylidene)Ethylenediimine

The silicon (IV) compounds possessing SiN₄O₂ (6), SiN₂O₂C₂ (7, 8), SiN₂O₂CCl (9) and SiN₄O₄ (10) coordinating frameworks have been synthesized in high yield by the reaction of the O,N,N,O- donor salen-type ligand N,N’-bis(salicylidene)ethylenediimine L with different silanes i.e. diethoxydiisocyanatosilane-(C₂H₅O)₂Si(NCO)₂ 1, dichlorodiphenylsilane-Ph₂SiCl₂ 2, dichloromethyl- phenylsilane-MePhSiCl₂ 3, trichlorophenylsilane-PhSiCl₃ 4 and silicon tetrachloride-SiCl₄ 5. The compounds 6–10 have been characterized by elemental analysis, IR, ¹H, ¹³C and ²⁹Si NMR and mass spectrometry. The decomposition reactivity of these compounds has been studied using a Thermal Gravimetric Analyzer (TGA) at a heating rate of 10°C/minute in an inert atmosphere.     

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 μ=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+(k′₂+k′₃)[H⁺],k ₁=5.98±1.64M ^?1 s^?1, andk ₂+k ₃=k′₂ K _Cu(II)-H-PVA ^?H +k′₃ K _Zn(II)-EDTA ^H =(5.91±0.89)×10⁷ M ^?2 s^?1.     

Solvent Extraction Studies of Rare Earths from Thiocyanate Medium with N,N,N´,N´-tetra(2-ethylhexyl) diglycolamide

The extraction behavior of rare earth (RE) elements from thiocyanate medium by N,N,N^’,N^’-tetra(2-ethylhexyl) diglycolamide (TEHDGA), a neutral extractant, has been investigated and the optimum conditions for their separations were determined. Isodecyl alcohol was used as phase modifier and a concentration of 5%(v/v) was found sufficient to mitigate third phase formation under our experimental conditions. The extraction mechanism of RE with TEHDGA was established by analyzing distribution data with slope analysis technique and showed the formation of a neutral species, RE(SCN)₃.2TEHDGA, in the organic phase. The extraction of rare earth decreased with increase in temperature indicating exothermic nature and the enthalpy change (ΔH) obtained for Y(III) was ?14.27 kJ/mol. Among various stripping agents studied, oxalic acid was found to be efficient in quantitative stripping of rare earths from TEHDGA. The extraction efficiency for all the rare earths by TEHDGA was also investigated. High separation factor of 6.4 for Er/Y pair at 0.03 M thiocyanate has indicated the feasibility of using TEHDGA as extractant to separate Y from heavy rare earths, in particular Er, from thiocyanate medium.     

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.     

Synergistic Extraction of Lanthanides(III) with N‐p‐Methoxybenzoyl‐N‐Phenylhydroxylamine and Neutral Nitrogen Donors

Abstract

We investigated the extraction equilibrium behavior of a series of trivalent lanthanide ions, (M³⁺), La, Pr, Eu, Ho, and Yb, from tartrate aqueous solutions using a chloroform solution containing N‐p‐methoxybenzoyl‐N‐phenylhydroxylamine (Methoxy‐BPHA or HL) combined with an adductant, 1,10‐phenanthroline (phen) or 2,2′‐bipyridyl (bipy). The synergistic species extracted were found to be {ML₂(phen)(HL)}⁺(1/2)Tar^2? and {ML₂(bipy)(HL)₂}⁺(1/2)Tar^2?, where Tar^2? is the tartrate ion. The stoichiometry, the extraction constants, and the separation factors of these systems were determined. We discuss the extractability and the separation factors in comparison with self‐adduct chelates, ML₃(HL)_2,(o), which were formed in the absence of phen or bipy.     

Preparation and characterization of three types of dinuclear iron(III) complexes with H2salbn,N,N′-disalicylidene-1,4-diaminobutane

By the reaction of the tetradentate Schiff base ligand H₂salbn, N,N^′-disalicylidene-1,4-diaminobutane with Fe^IIICl₃·6H₂O in the presence of Et₃N in MeOH a dinuclear iron(III) complex, [Fe^III(salbn)(μ-OMe)]₂ (1), has been obtained, whereas in EtOH, dinuclear complexes, [Fe^III(μ-salbn)]₂(μ-O) (2) and [Fe^III(salbn)]₂(μ-salbn) (3), are obtained. The structure of the complex 1 consists of two Fe(III) centers with one tetradentate salbn ligand (N₂O₂) which are bridged by two methoxo groups to yield a planar Fe₂O₂ core. On the other hand, in the complex 2, each of the two Fe(III) ions has a five-coordinate structure in which both salbn ligands act as a bridging didentate ligand and one oxygen atom bridges two Fe(III) ions to form a μ-oxo structure. The structure of the complex 3, which was obtained by accompanying with complex 2, consists of two six-coordinate Fe(III) centers in which each Fe(III) ion is coordinated by a tetradentate salbn ligand (N₂O₂) and one bridging salbn ligand (NO).     

Synthesis and Structure of 1D Copper(II) Polymers with Dissymmetrical N,N′-Bis(substituted)oxamide Ligands: Cytotoxicity and DNA-Binding Property

Two one-dimensional copper(II) coordination polymers with different dissymmetrical N,N′-bis(substituted)oxamide ligands were synthesized, namely {[Cu₂(dmaepox)(dabt)]pic·H₂O}_n (1) and {[Cu₂(dmapob)(dabt)]NO₃·0.6H₂O}_n (2), where H₃dmaepox and H₃dmapob stand for N-(2-carboxylatophenyl)-N′-[3-(methylamino)propyl]oxamidate and N-(2-carboxylatophenyl)-N′-[3-(dimethylamino)propyl]oxamidate, respectively, and dabt is 2?2′-diamino-4?4′-bithiazole. Polymer 1 was characterized by elemental analyses, IR and electronic spectra and single-crystal X-ray diffraction. The crystal structure reveals that polymer 1 consists of many binuclear copper(II) units bridged by cis-oxamide and carboxylate groups. The two copper(II) ions are located in square-planar and square-pyramidal coordination environments, respectively. The separations of the Cu(II) atoms bridged by oxamide and carboxylate groups are 5.2035(7) and 5.1196(7) Å, respectively. The crystal structure of polymer 2 has been reported in our previous paper. However, its relative properties were not studied. In order to compare the influence of different bridging ligands on the cytotoxicities and DNA-binding properties, the cytotoxicities and reactivities towards DNA of polymers 1 and 2 were investigated. The results suggest that the two polymers can interact with herring sperm DNA in the mode of intercalation with binding affinities following the order of 1 > 2, and this is consistent with their in vitro cytotoxicities.     

Studies on the Separation and Recovery of Palladium from Simulated High Level Liquid Waste (SHLW) Solution with Novel Extractant N,N,N′,N′-tetra (2-ethylhexyl) Dithiodiglycolamide DTDGA

The extraction properties of N,N,N',N'-tetra-(2-ethylhexyl) dithiodiglycolamide (DTDGA) have been evaluated for separation and recovery of palladium from simulated high-level liquid waste (SHLW) solution. Extraction of Pd was found to increase with increase in nitric acid concentration up to 4.0 M, above which the extraction remains almost constant. Acid uptake studies show 1:1 stoichiometry between DTDGA and HNO₃ at nitric acid concentration above 3.0 M. The acid uptake constant (K_H) was found to be 0.60 which could be due to the presence of two carbonyl groups of amidic moiety. DTDGA has shown very high extractability and selectivity for Pd over other metal ions present in SHLW. The separation factor (SF) for Pd over other metal ions was found to be more than 10⁴. Almost complete back extraction of palladium from organic phase was achieved with 0.01 M thiourea in 0.1 M nitric acid. Reusability studies of the extractant indicate that D_Pd remains almost constant even after five successive cycles of extraction and stripping. Two extraction stages will be required for complete extraction of 100 mg/L Palladium in 3.0 M nitric acid solution using 0.0025 M DTDGA/n-dodecane solvent system.     

Determination of N,N’, N’’-tris(3,7-dimethyloctyl)guanidine (TiDG) in Cesium Extraction Solvent

Several analytical methods were evaluated for determining the concentration of N,N’,N”-tris(3,7-dimethyloctyl)guanidine (TiDG) in a cesium extraction solvent. Of the methods evaluated, non-aqueous titration and ¹H NMR were shown to be successful at quantifying the amount of TiDG present in both a pure solvent extraction system, and a blended system containing an additional base, trioctylamine.     

Extraction of Uranium(VI) and Thorium(IV) from Nitric Acid Solution by N,N,N′,N′ – Tetraoctylglutaricamide

Synthesis and characterization of N,N,N′,N′-tetraoctylglutaricamide (TOGA) was carried out and used for extraction of U(VI) and Th(IV) from nitric acid solutions. The processes of extraction were determined by the slope analysis and by analyzing a function that allows the simultaneous treatment of all the experimental points obtained in different conditions. The different factors affecting the extraction distribution ratio(D) of U(VI) and Th(IV) (extraction concentration, concentrations of nitric acid, salting-out agent NaNO₃ concentration, equilibration time, temperature, and types of diluents) were investigated. The results obtained indicated that the extraction species of U(VI) and Th(IV) are mainly extracted as UO₂(NO₃)₂·1.0TOGA and Th(NO₃)₄·1.5TOGA. The apparent equilibrium constant of U(VI) and Th(IV) extraction determined are 3.35 ± 0.03 L³/mol³ and 1.87 ± 0.01 L⁵/mol⁵ at 298 ± 1 K. Thermodynamic parameters such as the free energy(ΔG), enthalpy(ΔH), and entropy(ΔS) changes associated with the extraction processes could be evaluated. Back-extraction of U(VI) and Th(IV) from organic phases was also studied.     

The nucleation effect of N,N′-bis(benzoyl) alkyl diacid dihydrazides on crystallization of biodegradable poly(l-lactic acid)

Five N,N??-bis(benzoyl) alkyl diacid dihydrazides were synthesized from benzoyl hydrazine and alkyl diacyl dichloride which were derived from alkyl diacid via acylation. PLLA/N,N??-bis(benzoyl) alkyl diacid dihydrazide samples were prepared by melt blending and hot-press forming process. The nucleation effect of N,N??-bis(benzoyl) alkyl diacid dihydrazide on crystallization of biodegradable poly(l-lactic acid) (PLLA) was investigated using differential scanning calorimetry (DSC) and vicat softening analysis. The results showed that five N,N??-bis(benzoyl) alkyl diacid dihydrazides acted as powerful nucleating agent for PLLA; with incorporation of N,N??-bis(benzoyl) alkyl diacid dihydrazide, the crystallization peak became sharper and shifted to higher temperature as the degree of supercooling decreased at a cooling rate of 1?°C/min from melt. The nucleation activities of five N,N??-bis(benzoyl) alkyl diacid dihydrazides were quantitatively determined. It is shown that N,N??-bis(benzoyl) suberic acid dihydrazide has higher nucleating activity than the other N,N??-bis(benzoyl) alkyl diacid dihydrazides. In the presence of N,N??-bis(benzoyl) alkyl diacid dihydrazide, the melting behavior of PLLA is affected significantly. In addition, the thermal stability of PLLA/0.8?% N,N??-bis(benzoyl) alkyl diacid dihydrazide is tested and reported. Compared to the neat PLLA, the onset degradation temperature of PLLA/0.8?% N,N??-bis(benzoyl) alkyl diacid dihydrazide samples has been decreased significantly.     

Miscibility of poly(styrene-co-vinyl phenol) with poly(ɛ-caprolactone)

Summary Poly(styrene-co-vinyl phenol) (STVPh)/poly(-caprolactone)(PCL) blends showed enhanced miscibility over polystyrene/PCL blend, and showed single glass transition temperature when the contents of vinyl phenol (VPh) in copolymer were higher than 10 wt % (maximum content of VPh in STVPh used in this study was 20 wt%). STVPh 4, STVPh 7, STVPh 10 (4, 7, 10 were VPh wt%)/PCL blends showed cloud points on heating for miscible blend system, and this phase separation was reversible on cooling. From melting point depression of PCL, interaction parameter, B. for miscible STVPh 12/PCL blend system was evaluated.     

Synthesis and Structural Studies of PdII/ZnII Architecture with N,N′-Bis(2-hydroxyethyl)ethylenediamine as Capping Ligand

A new compound of the composition [-{Zn-di-μ-bishydeten(O)-Zn}-μ-(CN)₂Pd(CN)₂] (1) was obtained from the reaction of PdCl₂, bishydeten [N,N′-bis(2-hydroxyethyl)ethylenediamine], KCN and ZnCl₂ in water/ethanol mixture. This dimeric polymer was characterized by IR spectroscopy and elemental analysis, and its thermal properties were studied by TG and DTG. In addition, the crystal structure was determined by single-crystal X-ray analysis. IR spectroscopy pointed out the existence of both terminal and bridged cyano ligands in the complex structure. When it comes to thermal analysis, the complex followed usual decomposition mechanism in which neutral ligands are decomposed first and then anionic ligands left the structure. Single crystal X-ray analysis revealed that 1 exhibited polymeric structure. An interesting feature of this complex is that ancillary bishydeten ligand acted as a bridge just like cyano groups did. In the complex structure, dimeric Zn units, which were gathered by –O atoms of bishydeten ligands in an asymmetric fashion, were bridged by tetracyanopalladate^II anions. 1D chain turned into 3D chains by means of intermolecular hydrogen bonds.     

Effects of N,N′-Ethylenebis(stearamide) on the Properties of Poly(ethylene terephthalate)/Organo-montmorillonite Nanocomposite

Poly(ethylene terephthalate)/organo-montmorillonite (PET/OMMT) nanocomposites were melt-compounded using twin screw extruder followed by injection molding. N,N′-ethylenebis(stearamide) (EBS) was selected as a dispersing agent to improve the dispersibility and exfoliation of OMMT clay in PET matrix. Morphological properties of the PET/OMMT nanocomposites were examined by using X-ray diffraction analysis, transmission electron microscopy and atomic force microscopy. Thermal properties of the nanocomposites were characterized by using dynamic mechanical thermal analysis. It was found that the OMMT are well dispersed and exfoliated in the presence of EBS. Remarkable enhancement in impact strength and storage modulus of PET/OMMT was achieved by the addition of EBS.     

Mechanism of removing arsenic(Ⅲ)with ferric chloride

采用XPS、SEM、TEM和红外分析的方法研究了三氯化铁除砷(Ⅲ)的机理。结果表明,三氯化铁是通过吸附共沉淀的方式去除水中的砷(Ⅲ)。XPS的数据表明在氯化铁处理含砷(Ⅲ)废水时有氧化还原反应发生;从SEM和TEM图可以看出随着溶液pH的升高,沉淀物从颗粒状态逐渐变为不规则的絮凝状态,颗粒粒径逐渐增大,表面有吸附物质存在;而从沉淀物的红外光谱图可以推断无砷酸铁生成。     

Tris(N,N′-dimethylurea)bis(nitrato-O,O′)manganese(II), the first example of a seven-coordinate manganese(II) complex with a monodentate organic ligand

Employing a variety of solvents and molar ratios, the reactions of Mn(NO₃)₂·6H₂O with N,N′-dimethylurea (DMU) afforded the adduct [Mn(NO₃)₂(DMU)₃] (1). X-ray analysis shows that the high-spin complex has a pentagonal bipyramidal geometry with two DMU oxygen atoms in axial positions and with two types of monodentate O-bonding for the DMU molecules, one of them being very unusual. The spectroscopic properties of the prepared complex are also discussed.     

Non-Dispersive Solvent Extraction of Neodymium using N,N,N’,N’-Tetraoctyl Diglycolamide (TODGA)

Hollow fiber contactor was used to study non-dispersive extraction (NDSX) of Nd³⁺ ions from aqueous solutions. N,N,N′,N′-tetraoctyl diglycolamide (TODGA) diluted with n-dodecane was used as the organic phase with di-n-hexyl octanamide (DHOA) as the phase modifier. The role of cations (H⁺/Na⁺) on the transport of Nd³⁺ ions has been investigated for this system. It was observed that H⁺ ion has a significant role to play in the Nd³⁺/TODGA complexation reaction. A mathematical model has also been developed to simulate the NDSX process in a hollow fiber contactor. A comparison has also been made between extraction profiles from the NDSX process and the hollow fiber supported liquid membrane (HFSLM) process. It was observed that NDSX gave comparatively faster rates of extraction in the presence of H⁺ ions but slower in the absence of H⁺ ions.     

Manufacture and Characterization of Biodegradable Nanocomposites Based on Nanoscale MgAl-Layered Double Hydroxide Modified with N,N′-(Pyromellitoyl)-bis-L-Isoleucine Diacid and Poly(vinyl alcohol)

Bionanocomposite films of poly(vinyl alcohol) (PVA) with Mg-Al LDHs were prepared with different compositions by solution-intercalation method. N,N′-(Pyromellitoyl)-bis-L-isoleucine diacid was synthesized and it was used for organo-modification of chiral MgAl-LDH in distilled water. Hybrid films of PVA and modified chiral LDH were prepared under ultrasonic irradiation technique. The effect of LDH contents on thermal, physicomechanical, and morphological properties of PVA films were investigated by using X-ray diffraction, Fourier transform infrared, thermogravimetric analysis, field emission scanning electron microscopy and transmission electron microscopy techniques. Mechanical data indicated improvement in the tensile strength and modulus with increasing of the LDH loading until 4%.