Mol Of Copper Research Articles

URJC-1: Stable and Efficient Catalyst for O-Arylation Cross-Coupling.

The design of metal-organic frameworks (MOFs) allows the definition of properties for their final application in small-scale heterogeneous catalysis. Incorporating various catalytic centers within a single structure can produce a synergistic effect, which is particularly intriguing for cross-coupling reactions. The URJC-1 material exhibits catalytic duality: the metal centers act as Lewis acid centers, while the nitrogen atoms of the organic ligand must behave as basic centers. The impact of reaction temperature, catalyst concentration, and basic agent concentration was evaluated. Several copper-based catalysts, including homogeneous and heterogeneous MOF catalysts with and without the presence of nitrogen atoms in the organic ligand, were assessed for their catalytic effect under optimal conditions. Among the catalysts tested, URJC-1 exhibited the highest catalytic activity, achieving complete conversion of 4-nitrobenzaldehyde with only 3% mol copper concentration in one hour. Furthermore, URJC-1 maintained its crystalline structure even after five reaction cycles, demonstrating remarkable stability in the reaction medium. The study also examined the impact of various substituents of the substrate alcohol on the reaction using URJC-1. The results showed that the reaction had high activity when activating substituents were present and for most cyclic alcohols rather than linear ones.

Stoichiometry: Reaction of Iron with Copper(II) Sulfate

Students use stoichiometry to deduce the appropriate equation for the reaction between solid metallic iron and a solution of copper(II) sulfate. This reaction produces solid metallic copper, which is precipitated as a finely divided red powder in a single displacement reaction. During the reaction, atoms from a solid metal exchange with different metal ions in a salt solution. The iron produced could be either Fe2+ or Fe3+. Students use stoichiometric principles to determine which of these ions is formed in the reaction. An excess of copper(II) sulfate (to make sure that all the iron is reacted) will be added to a known mass of iron. The metallic copper produced will be weighed. The masses of the iron and copper metals will be used to calculate the moles of iron used and the moles of copper formed. This lesson plan was developed and written by Tamara Fitzgarrald at Bradley University.

An Investigation into the Extraction Behavior of Copper from Sulfate Leach Liquor Using Acorga M5640 Extractant: Mechanism, Equilibrium, and Thermodynamics

The extraction of copper from sulfate leaching liquor was investigated using Acorga M5640 commercial extractant in kerosene diluent. The effects of important factors such as the extractant concentration, contact time, liquor pH, and temperature were examined on the separation factor Cu/Fe and the extraction efficiency of copper. The results indicated that nearly 92.32% copper was extracted from the leach liquor at 10% (v/v) Acorga M5640 concentration, 1:1 aqueous/organic phase ratio, 20 min contact time, pH 2.5, and 25 °C temperature. Also, the further increase in the values determined had no positive impact on the extraction of copper. Under these conditions, the separation factor Cu/Fe was obtained about 29.64. The extraction mechanism was studied applying the plot of log(D) – 2 pH against log [extractant] and it proved the association of two moles of Acorga M5640 for the extraction of one mole of copper. McCabe–Thiele diagram was constructed and a single-step extraction process was found to obtain the maximum extraction. Additionally, thermodynamic data were investigated and the extraction process was endothermic and non-spontaneous at 298 K (ΔH = 27.05 and ΔG = 15.52 kJ mol−1). Moreover, the loaded organic phase was stripped and 80.94% copper was recovered after 20 min using 10% sulfuric acid concentration.

Surface Characterization and Copper Release of a-C:H:Cu Coatings for Medical Applications

This paper focuses on the surface properties of a-C:H:Cu composite coatings for medical devices and how the release of Cu2+ ions from such coatings can be controlled. The released Cu ions have the potential to act as a bactericidal agent and inhibit bacterial colonization. A PVD–PECVD hybrid process was used to deposit a-C:H:Cu composite coatings onto Ti6Al4V substrates. We examine the layer surface properties using atomic force microscopy and static contact angle measurements. An increasing surface roughness and increasing contact angle of Ringer’s solution was measured with increasing copper mole fraction (XCu) in the coatings. The contact angle decreased when a supplementary bias voltage of −50 V was used during the a-C:H:Cu deposition. These findings are in line with earlier published results regarding these types of coatings. The release of Cu2+ ions from a-C:H:Cu coatings in Ringer’s solution was measured by anodic stripping voltammetry. Different layer structures were examined to control the time-resolved Cu release. It was found that the Cu release depends on the overall XCu in the a-C:H:Cu coatings and that an additional a-C:H barrier layer on top of the a-C:H:Cu layer effectively delays the release of Cu ions.

METHODS FOR COPPER EXTRACTION FROM PRECIPITATE AND USING OXIME MIXED WITH SODIUM CARBONATE

The paper covers experimental and theoretical studies of technical solutions for copper liquid extraction by organic extractants from sulfuric acid solutions that neutralize the negative effect of hydrogen ions released as a result of copper cations interaction with oximes on the copper extraction into the organic phase, and increase the technical and economic parameters of the process. In order to reduce the volume of processed solutions, copper extraction by the extractant solution in a diluent from the previously obtained thickened copper precipitate by sodium carbonate addition was studied. Subsequent operations for copper organic phase purification from metal impurities and re-extraction were carried out by methods known in liquid extraction. It was experimentally found that the use of copper pre-concentration in the precipitate makes it possible to increase the copper content in the extractant by 3—4 times to 1 g per 1 % (abs.) of the oxime content in the organic phase. It is required to maintain a ratio of 2 moles of oxime to 1 mole of copper in the precipitate to ensure rapid delamination and full extraction of copper. Dependencies of parameters were calculated for the stages of copper extraction from the thickened solution precipitate and extract washing. It was shown that extraction system parameters can be increased by using copper from the extractant emulsion solution obtained by mixing the oxime solution in a diluent and the aqueous solution of sodium carbonate. Based on the results of experiments, extractant emulsion with sodium carbonate added into the first stage of the extraction process makes it possible to significantly increase the copper distribution coefficient and saturate the extractant in terms of copper as much as possible. Maximum copper extraction from the solution is achieved at a molar ratio of carbonate and oxime in the emulsion equal to 1 : 2. The proposed technical solutions increase distribution coefficients and maximize the extractant working capacity during copper extraction. The lower volume of phases involved in extraction results in a substantially reduced number of extraction equipment and costs of raffinate purification from extractant and diluent destruction products. The proposed extraction methods can be used to extract copper from natural and technological sulfuric acid solutions, for example from mine waters and solutions generated when processing mineral raw materials and man-made waste.

Copper-gold nanoparticles encapsulated within surface-tethered dendrons as supported catalysts for the Click reaction

The synthesis, characterization, and catalytic testing of copper and copper:gold nanoparticles in melamine-based dendrons supported on SBA-15 is reported. It was found that by first making small gold nanoparticles using the dendrons as templates, stable copper(0) overlayers could then be successfully deposited. These samples were used as catalysts for the click reaction, with the most active samples possessing rates of 8.9 mol triazole produced/(mol copper – hour), nearly 50 times high than literature reports of copper nanoparticles in solution. In contrast, the gold nanoparticles themselves are inert for this reaction, consistent with the copper being deposited as an overlayer on the gold nanoparticles. Copper leaching was shown to be less pronounced for particles formed in the dendrons versus copper simply deposited on SBA-15. Larger dendrons lead to suppressed rates due to diffusion resistance with rates decreasing from 8.9 to 5.2 to 0.69 mol triazole produced/(mole Cu-hour) for G1, G2, and G3 respectively. Infrared spectroscopy was used to monitor the reaction in real time, and provided information about the various surface intermediates formed.

Optical Signatures of Impurity-Impurity Interactions in Copper Containing II-VI Alloy Semiconductors.

We study the optical properties of copper containing II-VI alloy quantum dots (CuxZnyCd1-x-ySe). Copper mole fractions within the host are varied from 0.001 to 0.35. No impurity phases are observed over this composition range, and the formation of secondary phases of copper selenide are observed only at xCu > 0.45. The optical absorption and emission spectra of these materials are observed to be a strong function of xCu, and provide information regarding composition induced impurity-impurity interactions. In particular, the integrated cross section of optical absorption per copper atom changes sharply (from 1 × 10 -2 nm3 to 4 × 10 -2 nm3) at xCu = 0.12, suggesting a composition induced change in local electronic structure. These materials may serve as model systems to understand the electronic structure of I-III-VI2 semiconductor compounds.

Effect of annealing temperature and copper mole ratio on the morphology, structure and magnetic properties of Mg0.5−xCuxZn0.5Fe2O4 nanoparticles prepared by the modified Pechini method

In this study, magnesium copper zinc ferrite (MCZ) nanoparticles were synthesized by the modified Pechini method. In this approach, the magnesium nitrate, copper nitrate, zinc nitrate, iron nitrate, citric acid and diethylene glycol (instead of ethylene glycol in conventional Pechini method) were used as a source of Mg2+, Cu2+, Zn2+, complex and stabilizer and solvent agent, respectively. The effect of annealing temperature and copper mole ratio on the morphology, structural and magnetic properties of Mg0.5xCuxZn0.5Fe2O4 (x=0–0.5) nanoparticles were investigated. Various characterization methods, including X-ray diffraction (XRD), field emission scanning electron microscope (FeSEM), energy-dispersive spectroscopy (EDS), X-ray mapping, Fourier transforms infrared spectroscopy (FTIR), adsorption-desorption isotherm and vibrating sample magnetometer (VSM) were used to study the phase, microstructure, particle size, elemental distribution, functional group determination, porosity and magnetic properties of nanoparticles, respectively. The results showed that cubic spinel phase with various morphologies such as semi-spherical, sheet-like shapes was obtained by the modified Pechini method. Furthermore, the nanoparticles with the x value of 0.2, annealed at 700°C have the highest saturation magnetization (Ms=56.5emu/g) among the other synthesized MCZ ferrite nanoparticles.

환원-산화법을 이용한 리드프레임 에칭폐액의 정제과정 설계

리드프레임에 구리합금소재를 사용할 경우 구리이외의 고농도의 철, 니켈, 아연 등이 포함되며 여기서 발생되는 에칭폐액은 지정폐기물로 지정되어 있다. 따라서 본 연구에서는 전기도금용 산화구리(II)를 제조하기 위해 고농도 중금속을 함유한 리드프레임 에칭폐액의 맞춤형 정제과정을 설계하였다. 리드프레임 에칭폐액의 경우 중금속 함유량이 높아 이온교환수지법 단독으로는 중금속을 제거하는데 한계가 있었다. 따라서 본 연구에서는 물에 대한 용해도차를 이용한 환원-산화법을 연계하여 염화구리(I)을 제조한 후 산화제인 과황산나트륨을 이용하여 염화구리(II)로 재회수하는 방법을 사용하였다. 최적 환원제로는 하이드라진을 선택하였고, 최적 첨가량은 구리 1.0 mol당 1.4 mol이다. 환원-산화법과 이온교환수지법을 연결하여 중금속을 제거할 경우 3회 반복 시 <TEX>$Fe^{3+}$</TEX> (4.3 ppm), <TEX>$Ni^{2+}$</TEX> (2.4 ppm), <TEX>$Zn^{2+}$</TEX> (0.78 ppm)로 전기도금용 산화구리(II) 제조용 원료로 사용이 가능할 것으로 사료된다. When copper alloy is used in etching process for the production of lead frame, the high concentration of heavy metals, such as iron, nickel and zinc may be included in the etching waste. Those etching waste is classified as a specified one. Therefore a customized design was designed for the purification process of the lead frame etching waste liquid containing high concentrations of heavy metals for the production of an electroplating copper(II) oxide. Since the lead frame etching waste solution contains highly concentrated heavy metal species, an ion exchange method is difficult to remove all heavy metals. In this study, a copper(I) chloride was manufactured by using water solubility difference related to the reduction-oxidation method followed by the reunion of copper(II) chloride using sodium sulfate as an oxidant. The hydrazine was chosen as a reducing agent. The optimum added amount was 1.4 mol per 1.0 mol of copper. In the case of removal of heavy metals by using the combination of reduction-oxidation and ion exchange resin methods, 4.3 ppm of <TEX>$Fe^{3+}$</TEX>, 2.4 ppm of <TEX>$Ni^{2+}$</TEX> and 0.78 ppm of <TEX>$Zn^{2+}$</TEX> can be reused as raw materials for electroplating copper(II) oxide when repeated three times.

Thermodynamic and experimental analysis of copper sulfide precipitation in copper-cyanide solutions

Most of the gold produced worldwide is still obtained by cyanidation, in spite of the difficulties encountered in the processing of some gold ores such as the dissolution of copper-bearing minerals in cyanide solutions. The leached copper forms complexes with cyanide and causes several operating problems, which have led to the development of copper removal/recovery processes, among them the industrially accepted SART process (sulfidization, acidification, recycling and thickening). Although the SART process is in use in gold production plants around the world, new challenges are appearing with the continuous varying of the mineralogy of ores (such as higher copper grades, changing the solution composition and complexity). The optimal SART operating conditions for a specific solution are not the same when the composition of the solution changes; consequently, the efficiency of this process can decrease. The present study is a thermodynamic approach, corroborated by laboratory experiments, to explain how the main variables of the process affect the efficiency of copper precipitation as cuprous sulfide (Cu2S). The variables considered were pH value, copper concentration, cyanide/copper molar ratio and sulfur/copper molar ratio, all of which were varied within the limits encountered in typical cyanidation solutions presenting the problem of copper. It was found that the variable that most affects the efficiency of the process was the pH value, since poor or no control of it can cause cuprous sulfide redissolution. The S/Cu molar ratio is also important: raising this ratio increases copper removal, but high ratios will also cause sulfide and cyanide losses. The effect of changing the CN/Cu molar ratio was negligible between 4 and 8. For a solution containing 300 mg/L copper and 490 mg/L cyanide, copper removal as high as 98.8% can be obtained with the addition of 0.6 moles of sulfide per mole of copper at pH = 6.

Calculation of combined diffusion coefficients in SF6-Cu mixtures

Diffusion coefficients play an important role in the description of the transport of metal vapours in gas mixtures. This paper is devoted to the calculation of four combined diffusion coefficients, namely, the combined ordinary diffusion coefficient, combined electric field diffusion coefficient, combined temperature diffusion coefficient, and combined pressure diffusion coefficient in SF6-Cu mixtures at temperatures up to 30 000 K. These four coefficients describe diffusion due to composition gradients, applied electric fields, temperature gradients, and pressure gradients, respectively. The influence of copper fluoride and sulfide species on the diffusion coefficients is shown to be negligible. The effect of copper proportion and gas pressures on these diffusion coefficients is investigated. It is shown that increasing the proportion of copper generally increases the magnitude of the four diffusion coefficients, except for copper mole fractions of 90% or more. It is further found that increasing the pressure reduces the magnitude of the coefficients, except for the combined temperature diffusion coefficient, and shifts the maximum of all four coefficients towards higher temperatures. The results presented in this paper can be applied to the simulation of high-voltage circuit breaker arcs.

Copper Exchanged Nanotitanate for High Temperature H2S Adsorption

The H2S breakthrough capacity of copper-exchanged Engelhard Titanosilicate-2 (ETS-2) was measured at temperatures up to 950 °C and it was found that the adsorbent efficiency remains unchanged across the entire temperature range. Below 750 °C, the adsorption capacity at breakthrough is 0.7 mol of H2S per mole of copper while above 750 °C the capacity of the adsorbent is halved. The change in H2S capacity is due to Cu2+ reduction by the H2 which is formed through the thermal dissociation of H2S. The adsorbent shows good potential for use over a wide range of operating temperatures in H2S scrubbing processes.

Structure, Optical Properties, and Magnetism of the Full Zn1–xCuxWO4 (0 ≤ x ≤ 1) Composition Range

Microcrystalline and submicrometer powders of Zn(1-x)Cu(x)WO(4) (0 ≤ x ≤ 1) have been prepared by a solid-state synthesis from stoichiometric quantities of the constituent d-block metal oxide and tungsten oxide as well as from a Pechini sol-gel synthesis starting from the d-block metal nitrate and ammonium metatungstate. The stoichiometry of the product is confirmed by inductively coupled plasma-atomic emission spectrometry (ICP-AES) analysis. X-ray diffraction shows that for the entire range of compositions, a single-phase product crystallizes in the wolframite structure, with a symmetry-lowering transition from P2/c to P1[overline] at x = 0.20, concomitant with the first-order Jahn-Teller distortion of Cu(2+). Far-IR spectroscopy corroborates that symmetry lowering is directly related to the tetragonal distortion within the CuO(6) octahedra, with the Zn-O A(u) symmetry mode at 320 cm(-1) (x = 0) splitting into two stretches at 295 and 338 cm(-1) (x = 0.3). UV-vis-NIR spectroscopy shows an optical absorption edge characteristic of an indirect band gap that linearly decreases in energy from 3.0 eV (x = 0) to 2.25 eV (x = 1). SQUID magnetometry shows that Zn(1-x)Cu(x)WO(4) (0.1 ≤ x ≤ 1) has an effective moment of 2.30 ± 0.19 μ(B) per mol copper, typical of Cu(2+) in extended solids. For high concentrations of copper (x ≥ 0.8), two transitions are observed: one at high-temperature, 82 K (x = 1.0) that decreases to 59 K (x = 0.8), and the Néel temperature, 23.5 K (x = 1.0) that decreases to 5.5 K (x = 0.8). For x < 0.8, no long-range order is observed. A physical 1:1 mixture of both CuWO(4):ZnWO(4) shows magnetic ordering identical to that of CuWO(4).

TiO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;/CuO Films Obtained by Citrate Precursor Method for Photocatalytic Application

In the present work, the hybrid catalyst films of TiO2/CuO containing up to 10% in mol of copper were deposited onto glass surface. Precursor solutions were obtained by citrate precursor method. Films were porous and the average particle size was 20 nm determined by FEG-SEM analysis. The photocatalytic activities of these films were studied using Rhodamine B as a target compound in a fixed bed reactor developed in our laboratory and UV lamp. It was observed that the addition of copper to TiO2 increased significantly its photocatalytic activity during the oxidation of Rhodamine B. The degradation exceeded 90% within 48 hours of irradiation compared to 38% when pure TiO2 was used. Moreover, there was a reduction in the particles band gap energy when compared to that of pure TiO2. These results indicate that the TiO2/CuO films are promising catalysts for the development of fixed bed reactors to be used to treat effluents containing azo dyes.

Attachment of 2,2-bipyridine onto a silica gel for application as a sequestering agent for copper, cadmium and lead ions from an aqueous medium

Attachment of 2,2-bipyridine onto a silica gel for application as a sequestering agent for copper, cadmium and lead ions from an aqueous medium A method was developed to attach 2,2-bipyridine (BP) onto a silica gel surface by a two-step reaction. The first step consisted of a reaction between the matrix and a silylating agent, 3-chloropropyltrimethoxysilane. In the second step of the reaction, a ligand molecule was attached onto Si-CPTS, yielding the product Si-BP. The modified material contained 0.431±0.01 mmol of 2,2-bipyridine per gram of modified silica, as confirmed by FT-IR spectra of the proposed structure. The surface modification was characterized by the BET technique, which revealed a decrease in the surface area from 614 to 450 m2 g-1. The series of adsorption isotherms for the metal ions were adjusted to fit a modified Langmuir equation. The maximum number of moles of copper, cadmium and lead ions adsorbed was 0.64, 0.53, and 0.54 mmol g-1, respectively. The surface saturation was calculated as φ fraction and the values obtained, Cu(II) = 1.160, Cd(II) = 1.044 and Pb(II) = 0.997, suggest a type 1:1 metal-ligand complex.

WALNUT BLIGHT SUSTAINABLE MANAGEMENT RESEARCH IN NEW ZEALAND

Walnut blight Xanthomonas arboricola pathovar juglandis is the most significant pest or disease issue in New Zealand commercial walnut (Juglans regia) production. Typical management has involved selection of less humid regions and copper based sprays. Research in New Zealand has included determining cultivars that show a promise of lower blight susceptibility and investigation of the effect of timing and form of copper sprays. There has been no clear success in the use of adjuvants to improve the efficacy of copper based sprays and no effective alternatives to copper sprays elucidated in research to date. Mankocide had previously demonstrated improved efficacy over Kocide even at lower copper levels. In this research, there was no apparent benefit in incorporating extra Mancozeb with Mankocide to match the copper mole for mole with dithiocarbamate. The use of copper methionine as an alternative form of copper yielded low efficacy on walnut blight. Efficacy of copper sprays was reduced by using copper methionine as a form of copper. Bacteriophages of X. arboricola pv. juglandis have a demonstrated capability of lysing all New Zealand isolates of the pathogen that have been collected in preliminary work. The potential of bacteriophages as a biological control agent is discussed but there is a need for a reliable bioassay to progress research further.

Indirect Determination of Trace Tetraborate by Differential Pulse Polarography Using Its Copper Complex and Application to Waste and Drinking Water

AbstractA new differential pulse polarographic (DPP) method has been developed for the trace determination of boron. Its most stable copper complex is used in 0.5 M KNO3 electrolyte since boron is not electroactive. By continuous addition of tetraborate to copper solution, the copper peak decreased first but then the peak became very small and nearly constant. This point was used for the boron determination. It was found that one mole of copper used two moles of tetraborate. Using this relationship, 1×10−5 M tetraborate could be determined. The quantification limit was 2.5×10−6 M and detection limit was 8×10−7 M. In the presence of complex forming ions such as Pb, Zn, and Cd, the borate found in sample was somewhat smaller because of their reaction with borate. But since their complexes were not as strong as copper, only a few percent of borate were used. No interference was observed in the presence of calcium, chloride and sulfate. This method is applied for the determination of B in borax ore, waste water of borax industries and tap water of Ankara city.

Knudsen effusion mass spectrometric determination of mixing thermodynamic data of liquid Al–Cu–Sn alloy

The vaporisation of a liquid Al–Cu–Sn system has been investigated at 1273–1473 K by Knudsen effusion mass spectrometry (KEMS) and the data fitted to a Redlich–Kister–Muggianu (RKM) sub-regular solution model. Thirty-one different compositions (41 samples) have been examined at eight fixed copper mole fractions, X Cu = 0.10, 0.20, 0.30, 0.333, 0.40, 0.50, 0.60 and 0.70. The ternary L-parameters, the thermodynamic activities and the thermodynamic functions of mixing have been evaluated using standard KEMS procedures. In addition, the same quantities were obtained from the measured ion intensity ratios of Al + to Cu +, Al + to Sn + and Cu + to Sn + using a mathematical regression technique. The intermediate data obtained directly are the RKM ternary L-parameters that are, as a function of temperature, as follows: L ( 0 ) = ( 14270 ± 1270 ) + ( 100.1 ± 7.6 ) T − ( 11.77 ± 0.93 ) T ln ( T ) ; L ( 1 ) = ( 145600 ± 9780 ) + ( 101.6 ± 58.7 ) T − ( 15.56 ± 7.14 ) T ln ( T ) ; L ( 2 ) = ( 76730 ± 1240 ) + ( 79.2 ± 7.4 ) T − ( 15.69 ± 0.91 ) T ln ( T ) . From the obtained ternary L-parameters the integral molar excess Gibbs energy, the excess chemical potentials, the activity coefficients and the activities have been evaluated. Using the temperature dependence of the activities, the integral and partial molar excess enthalpies and entropies can be also determined. In addition, for comparison, for some compositions, the Knudsen effusion isothermal evaporation method (IEM) and the Gibbs–Duhem ion intensity ratio method (GD-IIR) were used to determine activities and good agreement was obtained from the RKM model.

The oxidation of thiosulfates with copper sulfate. Application to an industrial fixing bath

This paper presents the transformation of thiosulfate using Cu(II) salts, such as copper sulfate, at pH between 4 and 5. The nature and kinetics of this process were determined. In the experimental conditions employed, the reaction between thiosulfates and Cu(II) ions produces a precipitate of CuS and the remaining sulfur is oxidized to sulfate, according to the following stoichiometry: 1 mol thiosulfate reacts with 1 mol Cu 2+ and 3 mol H 2O, generating 1 mol copper(II), 1 mol sulfate and 2 mol H 3O +. In the kinetic study, the apparent reaction order was ≈ 0 with respect to H 3O + concentration, in the interval 1.0 · 10 − 4 –1.0 · 10 − 5 M H 3O +; of order 0.4 with respect to Cu 2+ in the interval 0.21–0.85 g L − 1 Cu 2+; and of order 0 with respect to S 2O 3 2− in the interval 0.88–2 g L −1 S 2O 3 2−. The apparent activation energy was 98 kJ mol − 1 in the interval 15–40 °C. On the basis of this behavior an empirical mathematical model was established, that fits well with the experimental results. The thiosulfate transformation process using copper(II) sulfate was applied to an industrial fixing bath that proceeded from the photographic industry; after this, the resulting effluent contained less than 10 mg L − 1 of thiosulfates.

Purification and Characterization of a Copper-Containing Amine Oxidase from Mycobacterium Sp. Strain JC1 DSM 3803 Grown on Benzylamine

A bacterial semicarbazide-sensitive amine oxidase (SSAO) was purified and characterized from Mycobacterium sp. strain JC1 DSM 3803 grown on benzylamine. During the purification procedures, the enzyme was tending to aggregate and exhibited heterogeneity in native PAGE. The heterogeneous forms having amine oxidase (AO) activity could be separated by their native molecular weights using gel-filtration chromatography. Most of the AOs behaved as dimers (M(r) 150,000) composed of a 75-kDa subunit, but some aggregated to form tetramers (M(r) 300,000). Besides their native molecular weight, subunit composition and V(max) value, both forms (dimer and tetramer) have almost identical biochemical properties (e.g. subunit size, optimum pH and temperature, activation energy, K(m) value on benzylamine, substrate and inhibitor specificities). When AO activity was observed by activity staining, the best-oxidized substrate was benzylamine, although the AO also oxidized tyramine and histamine. The AO was strongly inhibited by semicarbazide and isoniazid, but KCN did not affect its activity. The purified enzyme was shown to contain 2.39 mol of copper per mole of subunit, but there were no evidences of topaquinone co-factor involvement, when tested by absorption spectrum analysis and redox-cycling staining for quinoprotein detection.