Magnetostructural correlations in the antiferromagnetic Co2−x Cux(OH)AsO4 (x=0 and 0.3) phases

Electrodialytic treatment of secondary mining resources for raw materials extraction: Reactor design assessment

The sustainability of mining activities is compromised due to the high amounts of mining residues generated that have to be disposed of, often in open dams, that may cause environmental deterioration, e.g. release of toxic elements to water supplies. These residues are, however, secondary resources of raw materials. In the case of Panasqueira mine, they even are a source of tungsten, considered a critical raw material. The present work aims to assess the electrodialytic process efficiency for raw materials extraction from Panasqueira mine residues. Experiments were performed with 2 and 3-compartment electrodialytic reactors, applying current intensities between 50 and 100 mA, from 4 to 14 days, and sample suspensions enhanced with NaCl or effluent. Additionally, control experiments with no current application were carried out. The results showed that a 3-compartment reactor operating at 100 mA, with NaCl as supporting electrolyte, presented the highest extraction of copper (13%), tin (10%), tungsten (13%) and arsenic (63%).

Twinned olivenite from Cap Garonne, Mine du Pradet – structure and magnetic behavior

Systematically twinned olivenite (Cu2(AsO4)OH) single crystals from Cap Garonne, Mine du Pradet, France, were studied by X-ray diffraction: P 21/n, a = 822.69(6) pm, b = 861.88(9) pm, c = 594.06(9) pm, β = 90.000(6)°, wR = 0.0224, 1621 F 2 values, 79 variables and a domain ratio of 0.501(1)/0.499(1). The temperature dependence of the magnetic susceptibility was well reproduced with a square-spin cluster model and an antiferromagnetic spin-exchange parameter of J/k B = 157(3) K.

Multiple heating rate kinetic parameters, thermal, X-ray diffraction studies of newly synthesized octahedral copper complexes based on bromo-coumarins along with their antioxidant, anti-tubercular and antimicrobial activity evaluation

Series of new Cu(II) complexes were synthesized by classical thermal technique. The biologically potent ligands (L) were prepared by refluxing 6-brom 3-acetyl coumarin with aldehydes in the presence of piperidine in ethanol. The Cu(II) complexes have been synthesized by mixing an aqueous solution of Cu(NO(3))(2) in 1:1 molar ratios with ethanolic bidentate ligands and Clioquinol. The structures of the ligands and their copper complexes were investigated and confirmed by the elemental analysis, FT-IR, (1)H NMR, (13)C NMR, mass spectral and powder X-ray diffraction studies respectively. Thermal behaviour of newly synthesized mixed ligand Cu(II) complexes were investigated by means of thermogravimetry, differential thermogravimetry, differential scanning calorimetry, electronic spectra and magnetic measurements. Dynamic scan of DSC experiments for Cu(II) complexes were taken at different heating rates (2.5-20 °C min(-1)). Kinetic parameters for second step degradation of all complexes obtained by Kissinger's and Ozawa's methods were in good agreement. On the basis of these studies it is clear that ligands coordinated to metal atom in a monobasic bidentate mode, by OO and ON donor system. Thus, suitable octahedral geometry for hexa-coordinated state has been suggested for the metal complexes. Both the ligands as well as its complexes have been screened for their in vitro antioxidant, anti-tubercular and antimicrobial activities. All were found to be significant potent compared to parent ligands employed for complexation.