Copper Acetate Solution Research Articles

Nanocrystalline CuO Thin Films for H<sub>2</sub>S Monitoring: Microstructural and Optoelectronic Characterization

Nanocrystalline copper oxide (CuO) thin films were deposited onto glass substrates by a spin coating technique using an aqueous solution of copper acetate. These films were characterized for their structural, mor-phological, optoelectronic properties by means of X-ray diffraction (XRD) scanning electron microscopy (SEM), UVspectroscopy and four probe method. The CuO films are oriented along (1 1 1) plane with the monoclinic crystal structure. These films were utilized in H2S sensors. The dependence of the H2S response on the operating temperature, H2S concentration of CuO film (annealed at 700。C) was investigated. The CuO film showed selectivity for H2S. The maximum H2S response of 25.2 % for the CuO film at gas concentra-tion of 100 ppm at operating temperature 200oC was achieved.

A hierarchical supra-nanostructure of HKUST-1 featuring enhanced H2 adsorption enthalpy and higher mesoporosity

A hierarchical supra-nanostructure of HKUST-1 was synthesized by directly mixing solutions of copper acetate and H3BTC (H3BTC = 1,3,5-benzenetricarboxylic acid) under ambient conditions, which exhibits enhanced H2 adsorption enthalpy and higher mesoporosity.

Crystallographic Analysis of Metal‐Ion Binding to Human Ubiquitin

The metal-binding ability of human ubiquitin (hUb) towards a selection of biologically relevant metal ions and complexes has been probed. Different techniques have been used to obtain crystals suitable for crystallographic analysis. In the first type of experiments, crystals of hUb have been soaked in solutions containing copper(II) acetate and two metallodrugs, Zeise salt (K[PtCl(3)(η(2)-C(2)H(4))]·H(2)O) and cisplatin (cis-[PtCl(2)(NH(3))(2)]). The Zeise salt is used in a test for hepatitis, whereas cisplatin is one of the most powerful anticancer drugs in clinical use. The Zeise salt readily reacts with hUb crystals to afford an adduct with three platinum residues per protein molecule, Pt(3)-hUb. In contrast, copper(II) acetate and cisplatin were found to be unreactive for contact times up to one hour and to cause degradation of the hUb crystals for longer times. In the second type of experiments, hUb was cocrystallized with a solution of copper(II) or zinc(II) acetate or cisplatin. Zinc(II) acetate gives, at low metal-to-protein molar ratios (8:1), crystals containing one metal ion per three molecules of protein, Zn-hUb(3) (already reported in previous work), whereas at high metal-to-protein ratios (70:1) gives crystals containing three Zn(II) ions per protein molecule, Zn(3)-hUb. In contrast, once again, copper(II) acetate and cisplatin, even at low metal-to-protein ratios, do not give crystalline material. In the soaking experiment, the Zeise anion leads to simultaneous platination of His68, Met1, and Lys6. Present and previous results of cocrystallization experiments performed with Zn(II) and other Group 12 metal ions allow a comprehensive understanding of the metal-ion binding properties of hUb with His68 as the main anchoring site, followed by Met1 and carboxylic groups of Glu16, Glu18, Glu64, Asp21, and Asp32, to be reached. In the case of platinum, Lys6 can also be a binding site. The amount of bound metal ion, with respect to that of the protein, appears to be a relevant parameter influencing crystal packing.

The synthesis of Ag/polypyrrole coaxial nanocables via ion adsorption method using different oxidants

Ag/polypyrrole (PPy) coaxial nanocables (NCs) were synthesized by an ion adsorption method. In this method, the pre-made Ag nanowires (NWs) were dispersed in the aqueous solution of copper acetate (Cu(Ac)2), and the Cu2+ ions adsorbed onto the surface of Ag NWs can oxidize pyrrole monomers to polymerize into uniform PPy sheath outside Ag NWs after the Cu(Ac)2-treated Ag NWs were re-dispersed in the aqueous solution of pyrrole. The morphology of NCs was characterized by transmission electron microscope (TEM) and scanning electron microscope (SEM). The relationship between the thickness of polymer sheath and the concentration of Cu(Ac)2 was established. As Cu(Ac)2 which served as the oxidant can also be replaced by AgNO3 in this synthesis, the differences on the structure of polymer sheath caused by different oxidants were studied by surface-enhanced Raman scattering (SERS), high-resolution transmission electron microscope (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Comparing with the characterization results of Ag/PPy NCs synthesized using AgNO3 as the oxidant which indicates the random arrangement of PPy chains at the interface between polymer sheath and Ag NWs, PPy chain oxidized by Cu2+ tends to show a relatively ordered conformation at the interface with the pyrrole rings identically taking the plane vertical to the surface of Ag NWs. In addition, although the main part of the polymer sheath was composed of PPy whatever kind of oxidant was used, the sheath of the NCs oxidized by Cu2+ is typical for the existence of Cu(I)–pyrrole coordinate structures with strong Cu(I)–N bond signal shown in XPS characterization.

Sonochemical synthesis, characterization and thermal and optical analysis of CuO nanoparticles

Nanoparticles of CuO were prepared by a novel sonochemistry route from copper acetate and sodium hydroxide in the presence of polyethylene glycol (PEG), polypropylene glycol (PPG) and polyvinyl alcohol (PVA). Variations in several parameters and their effects on the structural properties of nanoparticles (particle size and morphology) were investigated. 0.05 M solution of copper acetate in the presence of PEG gave the best results. The characterizations were carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), IR spectroscopy, thermal gravimetry analysis and differential thermal analysis (TGA/DTA).

Utilization of Poly(N-vinyl-2-pyrrolidone) to Enhance the Performance Properties as well as UV Protection of Ester Crosslinked Cotton Fabrics

Poly( N-vinyl-2-pyrrolidone) (PVP) was used as an additive in polycarboxylic acids finishing bathes. It was found that treating cotton fabric with aqueous solution containing 4% PVP, 8% citric acid, and 8% sodium hypophosphite monohydrate, followed by drying at 100°C for 3 minutes and then curing at 180°C for 90 seconds enhance the wrinkle recovery angle and tensile strength of the finished fabrics, as compared with fabrics treated under the same conditions but in the absence of PVP. The finished fabrics were post-treated separately with aqueous solutions of copper acetate and zinc acetate with the aim of improving the UV protection of these fabrics. According to the obtained data, copper acetate was found to have higher extent of UV protection than zinc acetate.

Facile synthesis of fluorescent quantum dot‐polymer nanocomposites via frontal polymerization

AbstractWe report an available approach for quickly fabricating CdS QD‐polymer nanocomposites via frontal polymerization (FP). First, we synthesized (3‐mercaptopropyl)‐1‐trimethoxysilane (MPS)‐capped CdS quantum dots (QDs). With these MPS‐capped CdS QDs containing mercapto groups, MPS‐capped CdS QDs can be easily incorporated into a poly(N‐methylolacrylamide) (PNMA) matrix via FP. A variety of features for preparing QD‐polymer nanocomposites, such as initiator concentration and CdS concentration, were thoroughly investigated. The fluorescence properties of QD‐polymer nanocomposites prepared via FP are comparatively investigated on the basis of ultraviolet–visible (UV–vis) spectra and photoluminescence (PL) spectra. Results show that the PL intensity of QD‐polymer nanocomposites prepared via the FP method is superior to that obtained by the traditional batch polymerization (BP) method. In addition, by measuring the changes of PL intensity of the samples immersed in different concentrations of copper acetate solution, we found the QD‐polymer nanocomposites can be ultrasensitive to copper ions. This FP process can be exploited as a facile and rapid way for synthesis QD‐polymer nanocomposites on a large scale, avoiding the fluorescence quenching of nanocrystals during incorporation nanocrystals into polymer matrices. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2170–2177, 2010

Adsorption of Copper Acetate onto Pretreated Activated Carbons over a Wide Concentration Range

The commercially available microporous activated carbon Kuraray GC was pretreated in two different ways: one was heated to 950 °C in 5% hydrogen and the other boiled in nitric acid for 5 h. BET surface area measurements and Boehm titrations were done to find the surface area and the numbers of surface functional groups for each carbon. A large range of linearly varying concentrations of aqueous copper acetate solutions was made and stirred with each sample of pretreated carbon. Atomic absorption spectroscopy, titrations, and weight measurements were employed to measure the amount of copper acetate actually adsorbed onto the respective carbon samples. The number of acidic functional groups on the carbon surface as determined by Boehm titrations in the case of the hydrogen treated sample and the nitric acid treated sample do not match with the usual Langmuir parameters both at low and high concentrations. Two distinct isotherm fittings have been obtained for both carbons; double Langmuir isotherms for the hydrogen-treated sample, and a low concentration Langmuir isotherm combined with a high concentration Freundlich isotherm for the nitric acid treated sample. The results have also been compared with the results for untreated Kuraray GC.

Effect of Polyvinyl Alcohol on Copper Leaching from Treated Wood

The new copper-based preservative systems leach a relatively high level of copper and, thus, generate some environmental concerns. Polyvinyl alcohol (PVOH) is known to complex with copper(II) and is water soluble. The effect of co-addition of fully hydrolyzed PVOH on the leaching of copper from wood treated with three different copper salts was examined. Southern pine sapwood wafers were treated with copper sulfate, copper acetate, and ammoniacal copper carbonate, all with 1 percent elemental copper in the waterborne solution, with and without 2 percent PVOH. The wafers were then dried and water leached for 2 weeks. PVOH co-addition greatly reduced the copper leached from wood treated with alkaline ammoniacal copper carbonate but not from wood treated with a slightly acidic solution of copper acetate or highly acidic copper sulfate.

Seed-Mediated Synthesis of Palladium Nanorods and Branched Nanocrystals and Their Use as Recyclable Suzuki Coupling Reaction Catalysts

In this study, we have used a simple seed-mediated synthesis process to prepare uniform Pd nanorods with average lengths of approximately 200 and 300 nm through the addition of 50-100 microL of 0.004 M copper acetate solution into the growth solution for the first time. Because of their long lengths, they nicely settled to the bottom of the reaction vial and can easily be separated from the suspended faceted particles. The nanorods have an average diameter of approximately 20 nm, so they have high aspect ratios of 10-15 or more. They can readily self-assemble into high-density packing structures on substrates. By increasing the volume of the copper acetate solution added to 250 microL, extensively branched Pd nanocrystals were obtained. The crystal structures of both particle morphologies have been examined. The nanorods possess a penta-twinned structure. Different growth directions have been found for the branched nanocrystals. The growth mechanism of these nanostructures was studied in great detail. A mixture of short Pd rods and faceted particles was formed first and elongated into long rods or branched nanocrystals with the assistance of copper atom deposition. A reduction potential of copper lower than that of palladium leads to periodic deposition and reoxidation of copper atoms on the growing rods and faceted particles. Use of other metal ions did not form long nanorods and branched nanocrystals. UV-vis spectra of the 200 nm Pd nanorods showed a significant absorption band in the near-infrared region with band maximum at approximately 1800 nm, while the 300 nm rods have band maxima of 2000-2100 nm. Both the nanorods and branched nanocrystals were found to serve as highly efficient and recyclable catalysts for catalyzing a Suzuki coupling reaction between phenylboronic acid and iodobenzene. They are also thermally stable under the reflux condition and can be easily removed from the product solution. These novel Pd nanostructures should find use in other palladium-catalyzed reactions.

How to suppress the spontaneous oscillatory in-vitro chiral conversion of α-substituted propionic acids? A thin-layer chromatographic, polarimetric, and circular dichroism study of complexation of the Cu(II) cation withl-lactic acid

Summary In our earlier investigations we showed, for the first time, with numerous practical examples that α-substituted propionic acids dissolved in the low-molecular-weight solvents are able to undergo spontaneous oscillatory in-vitro chiral conversion. In this study, we focused on attempting to suppress the spontaneous oscillatory in-vitro chiral conversion of α-substituted propionic acids using, as example, l-lactic acid dissolved in water in the presence of copper(II) cations. Our intention was to check whether the coordinate covalent bonds between copper(II) and l-lactic acid ligands prevented the latter species from oscillatory chiral conversion. To do this we stored aqueous solutions of copper(II) acetate and lactic acid in the molar ratios 1:1, 1:2, and 1:3 for a long period of time. Scrutiny of possible chiral conversion of l-lactic acid was carried out by thin-layer chromatography (TLC), polarimetry, and circular dichroism (CD) spectroscopy. Seemingly contradictory results were obtained from our investigations. From the TLC data it was apparent that chelating of copper(II) cations with l-lactic acid molecules did not result in suppression of the spontaneous oscillatory in-vitro chiral conversion of the acid. It was also established that different molar proportions of copper(II) cation and l-lactic acid molecules had somewhat different effects on the dynamics of conversion. In contrast, from polarimetric and circular dichroism studies it was apparent that when l-lactic acid is dissolved in water in the presence of copper(II) cations almost no chiral conversion is observed. Hence a final conclusion was drawn that chelating of copper(II) cations with l-lactic acid stabilizes the chiral structure of the acid in solution. Intermolecular interactions between the copper(II)-l-lactic acid complex and the silica gel stationary phase evidently affects the structure of the complex, however, most probably resulting in partial “liberation” of l-lactic acid ligands. Thus the chiral structure-stabilizing effect of copper(II) cations is apparently weakened by the TLC system and the freed l-lactic acid molecules can undergo chiral conversion.

Conditions and Mechanism for the Anodic Deposition of Cupric Oxide Films in Slightly Acidic Aqueous Media

An electrodeposition condition to anodically prepare CuO films using slightly acidic solutions of copper acetate (pH 5.5–6.4) is established. The plating solution and solutions with related compositions were investigated using cyclic and linear sweep voltammetry to elucidate the deposition mechanism. The key oxidation reaction that provides for CuO deposition appears to be the oxidation of Cu(II) ions to a Cu(III) species, which subsequently oxidizes water while being reduced to CuO. The solution pH appeared to be critical for these reactions as CuO forms only in solutions with pHs higher than 5.5. The use of acetate ions made it possible to elevate solution pHs to a proper range without chemically precipitating before the initiation of electro- deposition. The resulting films are translucent black and possess smooth surfaces on the microlevel. The as-deposited films are highly crystalline and showed well-defined optical and p-type photoelectrochemical properties that do not improve upon annealing at 300 and . The bandgap and flatband potential are estimated to be and in a solution , respectively.

Preparation of Cu2O Hollow Nanospheres under Reflux Conditions

AbstractCuprous oxide hollow nanospheres were prepared by heating a solution of copper acetate and hydrazine as a reductant in 2‐propanol at reflux. The size distribution of the nanospheres is mainly in the range 100–200 nm. The products were characterized by X‐ray diffraction, UV/Vis diffuse reflectance spectroscopy, SEM, and TEM. The results indicated that the Cu2O hollow nanospheres aggregated from small nanoparticles with an average size of ca. 6.6 nm. The UV/Vis diffuse reflectance spectrum indicated that the optical absorption edge of the hollow Cu2O nanospheres is redshifted relative to their solid counterparts. The influence of the reaction conditions, such as reaction temperature, reaction time, and the amount of water, on the formation of the nanospheres as well as their morphology were studied. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Layer-by-Layer Assembled Membranes of Protonated 18-Azacrown-6 and Polyvinylsulfate and Their Application for Highly Efficient Anion Separation

Ultrathin separation membranes were prepared upon alternating electrostatic adsorption of 1,4,7,10,13,16-hexaazacyclooctadecane (18-azacrown-6, hexacyclen, aza6) and polyvinylsulfate on porous polyacrylonitrile/polyethylene terephthalate (PAN/PET) substrates. The resulting composite membranes were highly permeable for electrolyte solutions, but the selectivity in ion transport was poor (alpha(Cl-/SO42-) = 2). However, after a treatment of the membrane with 0.1 M aqueous copper(II) acetate solution, the rejection of divalent anions was strongly enhanced. Separation factors alpha(Cl-/SO42-) = 110 and alpha(Cl-/SO32-) = 1420 were found. Spectroscopic studies indicate a highly specific complex formation of aza6 and copper acetate in the membrane. Treatment of the membranes with cobalt(II) and nickel(II) acetate also led to an enhancement of the separation factors, but the effect was much smaller. Detailed studies of the influence of the pH of the dipping solutions and number of deposited bilayers are also reported. A model is presented describing the origin of the high transport selectivity.

Gas-phase carbonylation of methanol to dimethyl carbonate on chloride-free Cu-precipitated zeolite Y at normal pressure

Chloride-free Cu/zeolite Y catalysts with Cu loading of 2–14% were prepared by precipitation from aqueous copper(II) acetate solutions and inert activation with an Ar flow at 700–750 °C for 15 h. This inert activation resulted in a considerable activity of the catalyst for the oxidative carbonylation of methanol (MeOH) to dimethyl carbonate (DMC) under normal pressure at 140–160 °C at 10–12 wt% Cu loading. Space-time yields (STY) of DMC up to 100 g DMC l −1 Cat h −1 were achieved with a feed composed of 36% MeOH, 48% CO, 6% O 2, and balance He at a gaseous hourly space velocity (GHSV) of 3000 h −1. A threshold of copper loading (5–6 wt%) was found to exist before catalysts became active. This is associated with the preferential location of copper at ion-exchange positions of the zeolite structure Y not accessible for the reactants. After saturation of these sites, the placement of copper ions within the supercage led to active catalysts. Characterization of samples at various stages of preparation by N 2 adsorption, XRD, XPS, ESR, 27Al-MAS-NMR, and TPR analysis revealed that the solid-state ion exchange during inert activation is accompanied by reduction of Cu 2+ to Cu +. Copper ions exert a stabilizing effect on the crystallinity of the zeolite (in situ XRD, 27Al-MAS-NMR). No crystalline metallic copper, cuprous oxide, or cupric oxide were formed (XRD), but melting occurred at 750 °C for catalysts with 14% copper loading, resulting in the formation of a glassy amorphous copper silicate/aluminate phase. The latter effect can be prevented by applying lower activation temperatures. The catalysts were prepared without using chloride, and the reaction did not require co-feeding of HCl for maintaining activity, as is needed for CuCl/zeolite catalyst formulations.

Synthesis and Characterization of Copper Hydroxide Acetate With a Layered Discoid Crystal

Titration of copper acetate solution with a dilute NaOH solution to pH 6.5 and subsequent aging at 313 K yielded copper hydroxide acetate with an analytical composition of Cu2(OH)3.1(OCOCH3)0.9nH2O (n ∼ 0.7) and layered discoid crystals. The chemical composition, structure, and holistic trend in thermal behavior are similar to those of the previously known Cu2(OH)3(OCOCH3)H2O phase with layered rectangular crystals. The most obvious difference between the two compounds is morphology of the crystals. The other major differences are found in stability of bonding of the interlayer acetate ions to solid phase and behavior in anion-containing solutions. The interlayer acetate ions in the present compound begin to be dissociated from the solid phase at ∼343 K while those in the previous compound are not dissociated below 383 K. The reaction of the present compound is topotactic in Cl− and NO3− aqueous solutions but reconstructive in a SO42− aqueous solution while the reaction of the previous compound in those solutions is topotactic.

A Cu/Al-MCM-41 mesoporous molecular sieve: application in the abatement of no in exhaust gases

Propane oxidation and reduction of NO to N2 with propane under oxidative conditions on a Cu-Al-MCM-41 mesoporous molecular sieve and Cu-ZSM-5 zeolites were studied. Both types of catalysts were prepared by ion exchange in aqueous solutions of copper acetate and characterised by X-ray diffraction (XRD), nitrogen sorption measurement, diffuse reflectance ultra-violet spectroscopy (DRS-UV), diffuse reflectance infra-red Fourier transform spectroscopy (DRIFTS) of the adsorption of CO on Cu+ and temperature-programmed reduction with hydrogen (H2-TPR). The NO reduction was performed between 200 and 500 oC using a GHSV = 42,000 h-1. H2-TPR data showed that in the prepared Cu-Al-MCM-41 all the Cu atoms are on the surface of the mesopores as highly dispersed CuO, which results in a decrease in specific surface area and in mesopore volume. H2-TPR together with DRIFTS data provided evidence that in Cu/ZSM-5 catalysts, Cu atoms are found as two different Cu2+ cations: Cua2+ and Cub2+, which are located on charge compensation sites, and their thermo-redox properties were different from those of Cu atoms in Cu-Al-MCM-41. The specific activity of the Cu2+ exchangeable cations in Cu-ZSM-5, irrespective of their nature, was much greater than that of the Cu2+ in Cu-Al-MCM-41, where they are found as CuO.

Correlation between the Cu/Al Value and Activity of Cu-ZSM-5 Catalysts and the Chemical Nature of the Starting Copper Salt

Cu-ZSM-5 catalysts for the selective reduction of NO with propane were obtained by ion exchange between H-ZSM-5 zeolite and an aqueous or aqueous ammonia solution of a copper salt (acetate or nitrate). Their Cu/Al values (%) defined as 2 × 100 (Cu : Al), where Cu : Al is the copper-to-aluminum atomic ratio, were determined as a function of ion exchange pH, which was varied by changing the copper salt and solution concentration. Cu/Al is primarily determined by the chemical nature of the starting copper salt. For a given salt, it is governed by the salt concentration in the solution. At a fixed salt concentration, Cu/Al is always larger for copper acetate than for copper nitrate. It can be raised to ≫100% by using an aqueous ammonia solution of a copper salt. Furthermore, it increases with increasing Si/Al in the starting zeolite if the other ion exchange conditions are equal. Irrespective of preparation conditions, the catalytic activity of Cu-ZSM-5 grows in proportion to Cu/Al. It peaks at Cu/Al ∼ 100% and then remains constant up to Cu/Al ∼ 400%. In order to achieve Cu/Al ∼ 100%, it is most appropriate to use a copper acetate solution.

Proper finishing treatments for sun‐protective cotton‐containing fabrics

AbstractTo enhance both the performance and ultraviolet‐protection properties of cotton‐containing fabrics, attempts have been made to use poly(carboxylic acid)s as non‐formaldehyde durable‐press finishing agents alone or in combination with certain additives followed by posttreatment with metal salt solutions. Furthermore, simultaneous dyeing and resin finishing in the presence of triethanolamine hydrochloride (TEA · HCl) or citric acid (CA) as a reactive additive along with different anionic or cationic dyestuffs have been examined. The results reveal that the ester crosslinking of cotton‐containing fabrics in the absence or presence of chitosan (5 g/L), β‐cyclodextrin (20 g/L), or choline chloride (20 g/L) as an additive results in an improvement in the fabric resiliency as well as the ultraviolet‐protection properties. The extent of the improvement is determined by the type of poly(carboxylic acid), type of additive, type of substrate (i.e., cotton or cotton/polyester blend), and pretreatment history (i.e., grey, bleached, or bleached and mercerized). The posttreatment of easy‐care finished fabric samples with a copper acetate solution (5 g/L) results in a dramatic improvement in the ultraviolet‐protection factor, especially with bleached cotton, grey cotton/polyester blend, and bleached cotton/polyester fabric samples, regardless of the additive. Simultaneous dyeing and resin finishing with Reactive Black 5 and Direct Violet 31, in the presence of TEA · HCL as a reactive additive, or with Basilene Red PB, in the presence of CA as a reactive additive, result in a sharp increase in both the depth of shade and the ultraviolet‐protection values, regardless of the substrate. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1024–1032, 2005

Use of low-temperature nanostructured CuO thin films deposited by spray-pyrolysis in lithium cells

Nanostructured CuO thin films were prepared by spray pyrolysis of aqueous copper acetate solutions at temperatures over 200–300 °C range. The textural and structural properties of the films were determined by scanning electron microscopy, atomic force microscopy, X-ray diffraction spectroscopy and X-ray photoelectron spectroscopy (XPS). Although the sole crystalline phase detected in the film was CuO, XPS spectra revealed a more complex surface structure due to the presence of undecomposed copper acetate that can be easily removed by Ar+ ion sputtering. The heating temperature was found to have little limited effect on the particle size and thickness of the films, which, however, increased significantly increasing deposition time. The film with the smallest grain size exhibited an excellent electrochemical response in Li battery electrodes and was capable of supplying sustained specific capacity as high as 625 A h kg−1 (50% greater than that delivered by bulk CuO and close to the theoretical capacity for the CuO⇔Cu reaction) upon extensive cycling.