Interfacial activity of 4-alkylphenylamines and the rate of palladium(II) extraction

Interfacial tension isotherms were determined in hydrocarbon-water systems for 4-alkylphenylamines containing from 6 to 16 carbon atoms in their alkyl chains, and the surface excess isotherms were computed and interpreted using various adsorption isotherms. Palladium(II) was extracted with 4-alkylphenylamines from 3 M HCI solutions. The maximum extraction rate of palladium(II) is observed for 4-decyl- and 4-dodecylphenylamines which exhibit good interfacial activity. Compounds soluble in the aqueous phase (4-hexylphenylamine) or in toluene (4-hexadecylphenylamine) extract palladium(II) slower than 4-decyl- and 4-dodecyl- phenylamines.     

Interfacial activity and rate of palladium(II) extraction with decyl pyridine monocarboxylates

Decyl isonicotiniate and decyl nicotiniate permit a rapid extraction of palladium(II) from its hydrochloride solutions. Decyl picoliniate is not a suitable extractant. 4-Octylphenylamine can act as a phase transfer catalyst when its concentration in the organic phase is at least 2·5 × 10^?4 M . It seems that the interfacial adsorption of pyridine carboxylates and of 4-octylphenylamine is not the decisive phenomenon in palladium(II) extraction. The negligible protonation of the pyridine-type extractants and the phase transfer catalysis explains well the quick extraction of palladium(II) with the commercial and highly hydrophobic extractant ACORGA CLX-50.     

Extraction chemistry of palladium I. Study on the mechanism of synergistic extraction of palladium (II) with 1-phenyl-3-methyl-4-dichloroacetopyrazolone-5-one and diphenyl sulfoxide

ABSTRACT

l-Phenyl-3-methyl-4-dichloroacetopyrazolone-5-one (HPMDCP), which is an acidic chelating β-diketone extractant, was synthesized by acylation reaction in dioxane medium. The behavior of synergistic extraction of palladium (II) with HPMDCP and diphenyl sulfoxide (DPSO) has been studied. The results show that an antagonistic effect was observed under the given conditions. To understand this phenomenon, a preliminary work was performed to explain the mechanism of this reaction. According to the theory of the corresponding solutions (TCS), the association reaction between HPMDCP and DPSO in the organic phase was discussed. The results show that the associate species HPMDCP.DPSO formed in chloroform medium is the main reason why an antagonistic extraction effect occurs. The association constant between HPMDCP and DPSO in the extraction process was calculated to be 4.2.     

Promising Anticancer Activity of [Bis(1,8-quinolato)palladium (II)] Alone and in Combination

Due to similar coordination chemistry of palladium and platinum, a large number of palladium compounds as well have been investigated for their anticancer activity. In the present study, we describe synthesis, characterization, and anticancer activity of palladium complex [Bis(1,8-quinolato)palladium (II)], coded as NH3 against seven different cancer cell lines. NH3 is found to have higher antitumor activity than cisplatin against both parent ovarian A2780 cell line and cisplatin-resistant cell lines. Also, NH3 has the lower IC₅₀ value in HT-29 colorectal cancer cell line. The higher antitumor activity of NH3 is due to the presence of bulky 8-Hydroxyquinoline ligand, thus reducing its reactivity. Proteomic study has identified significantly expressed proteins which have been validated through bioinformatics. NH3 has been found to be less toxic than cisplatin at 2.5 mg/kg and 5 mg/kg dosages on mice models. Binary combinations of NH3 with curcumin and epigallocatechin gallate (EGCG) have demonstrated dose and sequence-dependent synergism in ovarian and colorectal cancer models. All of the preclinical studies indicate promising therapeutic potential of NH3 [Bis(1,8-quinolato)palladium (II)] as an anticancer drug.     

Determination of cobalt(II), nickel(II) and palladium(II) Ions via fabric phase sorptive extraction in combination with high-performance liquid chromatography-UV detection

A method for the determination of Co(II), Ni(II) and Pd(II) in aqueous samples by fabric phase sorptive extraction-high-performance liquid chromatography-UV detection (FPSE-HPLC-UV) is developed. A preconcentration step was necessary due to the trace level concentrations of these elements in aqueous samples. Sol-gel polytetrahydrofuran nanocomposite was selected as the sorbent. All major FPSE parameters were optimized. The limit of detection for Co(II), Ni(II) and Pd(II) morpholino dithiocarbamate complexes were found at much lower concentration level compared with earlier reported data with excellent reproducibility. The new FPSE-HPLC-UV method can be used for routine determination of these metal species in various aqueous environmental samples and in different alloys.     

Effect of separation mechanism on the kinetics of Zn(II) flotation

ABSTRACT

In this study, the kinetics study and separation mechanism of zinc ion removal from synthetic wastewater were investigated using the foam separation process. With increasing the pH, Zn(II) recovery increased, in which foam fractionation occurred at pH 1.5, 3 and 5.5 and ion flotation at pH 8. The kinetics study was also used to determine separation mechanism. The order of Zn(II) foam fractionation was n = 1, while the order of Zn(II) ion flotation was n = 2 at the first stage and n = 0 at the second stage. Water recovery kinetics also increased with increasing ionic strength.     

Organometallic diaqua complexes of palladium(II)

The protonation of [(C₆F₅)LPd(μ-OH)₂PdL(C₆F₅)] by triflic acid (CF₃SO₃H) results in the formation of the diaqua complexes [Pd(C₆F₅)L(H₂O)₂][CF₃SO₃] (L=PPh₃ (1) or AsPh₃ (2)). The crystal structure of 2 was elucidated by X-ray diffraction analysis revealing the presence of tetrameric units involving hydrogen bonds.     

Polymerization of Methylthiirane initiated by platinum(II)- and palladium(II)-complexes

Summary Some complexes derived from platinum(II) and palladium(II) initiate stereospecific polymerization of methylthiirane in homogeneous phase.When the metal environment is chiral no stereoelective polymerization occurs. The mechanism of polymerization initiated by platinum complexes seems to be similar to those proposed for zinc or cadmium derivatives whereas analogies are apparent between palladium and some aluminum derivatives, especially in the formation of great amounts of disulfide bonds during the polymerization.     

Crystal structures of palladium(II) and copper(II) complexes of meso-phenyl tripyrrinone

Meso-phenyl tripyrrinone (2), which is derived directly from N-confused porphyrin by Cu(II)-assisted oxygenolysis, can serve as a metal coordination ligand using three nitrogens and one oxygen in the core. The crystal structures of Pd(II) and Cu(II) complexes show the similar square-planar N₃O-coordination but the mode of oligomeric chains formed in the crystals by π–π stacking interaction is different: zig–zag for Cu(II) and straight for Pd(II) complex.     

Reduction of nitroaromatics with poly(vinylpyridine) complexes of palladium(II) and platinum(II)

Palladium(II) and platinum(II) anchored to 2- and 4-vinylpyridine polymers of different molecular weights were used for the dihydrogen reduction of various nitroaromatics and benzaldehyde in ethanol at 50°C. Palladium(II) complexes were far more effective than their platinum(II) analogues and the activity decreased with increasing molecular weights of the polymers. The nitroaromatics were selectively and almost completely reduced to the corresponding anilines. During reduction, the orange palladium(II) complexes changed to voluminous green precipitates, which could be used repeatedly and preserved for a long time without any loss of activity. A rate equation of the type: rate = K[Cat] [H₂] has been derived and a reduction mechanism has been proposed on the basis of experimental results and kinetic data.     

The structures and decomposition products of palladium(II) and platinum(II) terpyridine phenoxide complexes

A series of complexes of formula [Pd(OR)(terpy)]BF₄ and [Pt(OR)(terpy)]BF₄ (ROH=a substituted phenol; terpy=2,2^′:6^′,2^″-terpyridine) have been prepared by reaction of [M(OH)(terpy)]BF₄ (M=Pd, Pt) with ROH. One Pd(II) and one Pt(II) complex in this series have been structurally characterised. These compounds are very acid sensitive; decomposition products resulting from recrystallisation of two of these compounds from MeNO₂ or MeCN have been crystallographically characterised.     

Investigation of the mechanism and kinetics of dissolution of nickel(II) and nickel(III) oxides in sulfuric acid

Based on the experimental data on the effect of pH and the H₂SO₄ concentration on the dissolution rate of nickel oxides, the nature of the limiting stage is revealed, which consists in the formation of surface compounds and their subsequent transfer into the electrolyte solution. The intermediate products of dissolution of nickel(II) oxide in sulfuric acid are identified.     

On the kinetics and mechanism of the Cd(II)/Cd(Hg) system in acid media

The kinetics and mechanism have been investigated in the Cd(II)/Cd(Hg) system in 2 M NaClO₄ + 1 M HClO₄, at 25 ± 0.5°C. The galvanostatic single-pulse method has been used. The value of double-layer capacity, exchange current density, as also the α value, k_s, and the partial reaction order of each of the component which takes place in the reaction, have been determined on the grounds of different kind of anions in the solution. The two-step single-electron exchange mechanism has been suggested, as also the one-step exchange reaction in combination with the reaction of disproportionation.     

The syntheses,characterization and fluorescence spectra of novel,octakis(alkylthiophthalocyanato) nickel(II) and palladium(II) complexes

The syntheses, characterization and fluorescence studies of several {octakis(alkylthio)phthalocyanato} palladium(II) and nickel(II) complexes are presented. The absorption spectra of some of the complexes showed extra peaks which are attributable to non-planar distortion, the extent of which, was found to dependent on alkyl chain length. The fluorescence excitation spectra of the nickel(II) derivatives were not in agreement with their absorption spectra, owing to structural changes upon excitation. Fluorescence quantum yields were very low (<1%) for all complexes as a consequence of the open-shell electronic structures of nickel(II) and palladium(II).     

Sulfhydryl functionalized activated carbon for Pb(II) ions removal: kinetics,isotherms, and mechanism

ABSTRACT

The novel organic capturing agent was synthesized through the amidation of 2-amino-5-guanidinopentanoic acid anchored on activated carbon with dimercaptosuccinic acid for effective elimination of toxic Pb(II) ions originated from contaminated water. The SH@AGPA@AC was examined by FT-IR, thermo-gravimetric analysis–DTG, scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett Teller (BET), and X-ray photoelectron spectroscopy (XPS). The influence of experimental conditions like pH, adsorption time, initial Pb(II) concentration, and temperature on the performance of Pb(II) capturing was examined. The results revealed that the SH@AGPA@AC adsorbent was successfully fabricated. The kinetics data achieved a quite fit with the pseudo-second-order model. The SH@AGPA@AC obeyed the Langmuir model. The Pb(II) was fully desorbed with HCl (0.1 M) acid and then ready to reuse in the subsequent cycle after rinsing with water with the identical organic moieties of the SH@AGPA@AC. Thus, the SH@AGPA@AC was considered as an achievable and auspicious candidate for Pb(II) elimination from contaminated water with the highest adsorption capacities amount to 116.3 mg/g.     

电渗析与萃取耦合技术分离Ni(II)与Co(II)

为实现混合溶液中Ni(II)与Co(II)的分离,设计了电渗析与萃取耦合的集成分离技术,借助自行设计的设备,在选P507为萃取剂后,考察了电流密度、酸用量、体积流量、萃取剂皂化率、原料与萃取剂摩尔比、萃取方式等对分离效果的影响.结果表明:在实验范围内,电流密度3.8 mA/cm2,酸用量为理论用量的1.3倍,体积流量60 L/h、皂化率60%,原料与萃取剂摩尔比1:1.7为优取的操作条件;料液循环重复萃取,能显著提高分离效果.由此表明,电渗析与萃取耦合的分离技术,可分离混合体系中的Ni(II)、Co(II),且无需溶剂参与.     

Effects of crosslinking degree of poly(vinyl alcohol) hydrogel in aqueous solution: kinetics and mechanism of copper(II) adsorption

Recently, a renewed interest in hydrogels for heavy metal removal of wastewater has been growing because of embarking opportunities in industrial applications. One of the most interesting hydrogels potentially used as absorbent is poly(vinyl alcohol) (PVA), owing to its biocompatibility. In this study, the adsorption capacity of copper(II) ion onto PVA hydrogel (PVAH) adsorbents with different crosslinking degrees of 1, 3 and 5 % from aqueous solution was investigated. The PVAH adsorbents were prepared from PVA, using glutaraldehyde as a crosslinking agent. Their properties were determined by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and water absorption measurement. The results showed that PVA was crosslinked with glutaraldehyde. It exhibited an equilibrium swelling ratio in the range of 195–250 %, depending on the crosslinking degree with different PVAH structures defined from SEM micrographs. The adsorption capacity of copper(II) ion onto PVAH adsorbents was investigated and found that higher crosslinking degree decreased the absorption capacity. This behavior is due to the decrease in reactive sites, resulting in the decrease of interaction between copper(II) ion and PVA. Besides, the adsorption capacity also depended on contact time, pH and temperature. The adsorption process followed pseudo-second-order kinetic, having a 0.99 correlation coefficient. Intraparticle diffusion was confirmed by the adsorption mechanism controlled by particle and film diffusions.     

Adsorption capacity,kinetics, and mechanism of copper(II) uptake on gelatin‐based hydrogels

Gelatin‐based hydrogels were synthesized and characterized for use as Cu²⁺‐ion sorbents. Gelatin was crosslinked in the presence of two different monomers, that is, acrylamide (AAm) and/or 2‐hydroxypropyl methacrylate, with N,N‐methylenebisacrylamide, ammonium persulfate, and sodium bicarbonate. The as‐prepared hydrogels were further characterized by scanning electron microscopy, Fourier transform spectroscopy, and the study of their swelling behavior as a function of temperature, time, and pH to evaluate their structure–property relationships. The hydrogels were observed to be good sorbents of Cu²⁺, and a maximum uptake of 84.8% was observed within 2 h at 37°C and with 10 ppm of the Cu²⁺‐ion solution for the gelatin and polyacrylamide hydrogel, which also exhibited the maximum retention capacity at 14.9 mg/g after four feeds. All of the experimental data exhibited good matches with the Langmuir isotherm and followed pseudo‐second‐order kinetics. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Polymer‐supported palladium(II) complexes and their catalytic study

Chloromethylated poly(styrene–divinylbenzene) copolymers with 8 and 14% crosslinking was functionalized to a Schiff‐base‐bearing polymer by the sequential oxidation of the chloromethyl group to an aldehydic group and subsequent condensation with a base. The anchoring of the metal ion to the liganded polymer beads was carried out by its reaction with an ethanolic solution of palladium(II) chloride. The physicochemical properties of the supported catalyst, including surface area, bulk density, and the swelling of the polymer in polar and nonpolar solvents, were studied. The catalysts were characterized by various techniques, including elemental analysis, DTA–thermogravimetric analysis, Fourier transform infrared spectroscopy, and diffuse reflectance spectroscopy. The surface morphology of the catalyst was studied by scanning electron microscopy. The catalytic hydrogenation of cis‐cyclooctene was investigated with the immobilized catalysts. The effects of various reaction parameters, including catalyst concentration, temperature, and hydrogen pressure on the reduction of olefin, were studied. The rate of the reaction was determined from hydrogen uptake measurements. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 370–378, 2003