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In order to systematize and expand knowledge about copper-containing composite materials as hybrid ion exchangers, in this study, fine metallic copper particles were dispersed within the matrix of a carboxyl cation exchanger (CCE) with a macroporous and gel-type structure thanks to the reduction of Cu2O particles precipitated within the matrix earlier. It was possible to introduce as much as 22.0 wt% Cu0 into a gel-type polymeric carrier (G/H#Cu) when an ascorbic acid solution was used to act as a reducer of Cu2O and a reagent transforming the functional groups from Na+ into the H+ form. The extremely high shrinkage of the porous skeleton containing –COOH groups (in a wet and also dry state) and its limited affinity for water protected the copper from oxidation without the use of special conditions. When macroporous CCE was used as a host material, the composite material (M/H#Cu) contained 18.5 wt% Cu, and copper particles were identified inside the resin beads, but not on their surface where Cu2+ ions appeared during drying. Thermal analysis in an air atmosphere and under N2 showed that dispersing metallic copper within the resin matrix accelerated its decomposition in both media, whereby M/H#Cu decomposed faster than G/H#Cu. It was found that G/H#Cu contained 6.0% bounded water, less than M/H#Cu (7.5%), and that the solid residue after combustion of G/H#Cu and M/H#Cu was CuO (26.28% and 22.80%), while after pyrolysis the solid residue (39.35% and 26.23%) was a mixture of carbon (50%) and metallic copper (50%). The presented composite materials thanks to the antimicrobial, catalytic, reducing, deoxygenating and hydrophobic properties of metallic copper can be used for point-of-use and column water/wastewater treatment systems. [ABSTRACT FROM AUTHOR]

The biogeochemistry of post-mining areas is important because of their impact on the environment and the possibility of remediating such areas. Such a hostile environment is also a source of acidophilic microorganisms that can dissolve minerals that might be applied in the extractive metallurgy of low-grade oxide ores. Therefore, the study used autochthonic microorganisms isolated from water and sediment samples taken from places affected by acid mine drainage. The acidophiles were isolated under aerobic and anaerobic conditions. Genomic analysis revealed low prokaryotic diversity. The genera with a relative abundance greater than 1% were Acidithiobacillus (39.8-84.2%), Ferrimicrobium (26.4-34.4%), Acidiphilium (8.31-28.8%), and Leptospirillum (9.6-32.1%). Aerobic bacteria were adapted to reduce iron(III) under a nitrogen atmosphere and the presence of elemental sulfur as an electron donor. It was shown that increasing the amount of sulfur (1-5 g) had little effect on the process kinetics. In anaerobic bottom sediments, Sulfobacillus (45.7%) and Acidisphaera (32.7%) predominated. Microorganisms showed the fastest reduction activity when glycerol was used as an electron donor. Four weeks of anaerobic-controlled bioreduction of laterites yielded nickel and magnesium at 33.3% and 77.3%, respectively, which could have potential applications in the processing of laterites. [ABSTRACT FROM AUTHOR]

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