The chemical synthesis of monoatomic metallic copper is unfavorable and requires inert or reductive conditions and the use of toxic reagents. Here, we report the environmental extraction and conversion of CuSO₄ ions into single-atom zero-valent copper (Cu⁰) by a copper-resistant bacterium isolated from a copper mine in Brazil. Furthermore, the biosynthetic mechanism of Cu⁰ production is proposed via proteomics analysis. This microbial conversion is carried out naturally under aerobic conditions eliminating toxic solvents. One of the most advanced commercially available transmission electron microscopy systems on the market (NeoArm) was used to demonstrate the abundant intracellular synthesis of single-atom zero-valent copper by this bacterium. This finding shows that microbes in acid mine drainages can naturally extract metal ions, such as copper, and transform them into a valuable commodity.

The Brazilian energy grid is considered as one of the cleanest in the world, because it is composed of more than 80% of renewable energy sources. This work aimed to apply the levelized costs (LCOH) and environmental cost accounting techniques to demonstrate the feasibility of producing hydrogen (H₂) by alkaline electrolysis powered by the Brazilian energy grid. A project of hydrogen production, with a lifetime of 20 years, had been evaluated by economical and sensitivity analysis. The production capacity (8.89 to 46.67 kg H₂/h), production volume (25 to 100%), hydrogen sale price (1 to 5 USD/kg H₂) and the MAR rate were varied. Results showed that at 2 USD/kg H₂, all H₂ production plant sizes are economically viable. On this condition, a payback of fewer than 4 years, an IRR greater than 31, a break-even point between 56 and 68% of the production volume and a ROI above 400% were found. The sensitivity analysis showed that the best economic condition was found at 35.56 kg H₂/h of the plant size, which generated a net present value of USD 10.4 million. The cost of hydrogen varied between 1.26 and 1.64 USD/kg and a LCOH of 37.76 to 48.71 USD/MWh. LCA analysis showed that the hydrogen production project mitigated from 26 to 131 thousand tons of CO₂, under the conditions studied.

Background: The solar photo-Fenton process has enormous potential for becoming a viable alternative to conventional processes for the treatment of industrial wastewater. However, the costs associated with the use of artificial irradiation have hindered many times industrial application of these processes. Method of Approach: In this work, the photo-Fenton remediation of various industrial wastewaters (containing silicones, pesticides, phenol and hydrocarbons, model, and real) in aqueous systems has been studied using Fe(II), $H2O2$, and UV-visible sunlight. Experiments were carried out using a concentrating parabolic trough reactor (PTR) and a nonconcentrating falling-film reactor. Results: In general, at low contaminant concentration, more than 90% of the total organic carbon content could be converted to inorganic carbon within about $2–3h$, using sunlight, in reactors of different geometry. Conclusions: Solar light can be used either as an effective complementary or alternative source of photons to the photo-Fenton degradation process of a diversity of chemical pollutants.