In this study, we present a pre-feasibility analysis that examines the viability of implementing autonomous green hydrogen production plants in two strategic regions of Chile. With abundant renewable energy resources and growing interest in decarbonization in Chile, this study aims to provide a comprehensive financial analysis from the perspective of project initiators. The assessment includes determining the optimal sizing of an alkaline electrolyzer stack, seawater desalination system, and solar and wind renewable energy farms and the focus is on conducting a comprehensive financial analysis from the perspective of project initiators to assess project profitability using key economic indicators such as net present value (NPV). The analyses involve determining appropriate sizing of an alkaline electrolyzer stack, a seawater desalination system, and solar and wind renewable energy farms. Assuming a base case production of 1 kiloton per year of hydrogen, the capital expenditures (CAPEX) and operating expenses (OPEX) are determined. Then, the manufacturing and production costs per kilogram of green hydrogen are calculated, resulting in values of USD 3.53 kg⁻¹ (utilizing wind energy) and USD 5.29 kg⁻¹ (utilizing photovoltaic solar energy). Cash flows are established by adjusting the sale price of hydrogen to achieve a minimum expected return on investment of 4% per year, yielding minimum prices of USD 7.84 kg⁻¹ (with wind energy) and USD 11.10 kg⁻¹ (with photovoltaic solar energy). Additionally, a sensitivity analysis is conducted to assess the impact of variations in investment and operational costs. This research provides valuable insights into the financial feasibility of green hydrogen production in Chile, contributing to understanding renewable energy-based hydrogen projects and their potential economic benefits. These results can provide a reference for future investment decisions and the global development of green hydrogen production plants.

In copper smelting processes, acidic effluents are generated that contain inorganic contaminants such as arsenic and copper. Nowadays, the treatment of wastewater is done by physicochemical methods without copper recovery. Electrodialysis is an alternative process that can recover copper. Moreover, when electrocoagulation is applied to remove arsenic from wastewater, a more stable final sludge of less volume is obtained. The present research studies the application of a combined electrodialysis and electrocoagulation process to (1) recover Cu and (2) precipitate and remove arsenic simultaneously in the same batch reactor, using synthetic wastewater that simulates wastewater from a copper smelter. Copper and arsenic could be removed and separated by the electrodialysis part, and the electrocoagulation of arsenic was verified. With electrodialysis, the arsenic and copper removals were 67% and 100%, respectively, while 82% of the arsenic arriving at the electrocoagulation part of the cell could be precipitated and removed by this process. Initial concentrations were around 815 mg L⁻¹ Cu and 7700 mg L⁻¹ As. The optimal current was found to be 1.36 A due to the shorter treatment times necessary to get removal percentages, recovery percentages and energy/removed copper mass ratios in the same ranges as the values achieved with a current of 1.02 A. In summary, the combined process is a promising tool for simultaneous copper recovery and arsenic removal.

This study analyses pyrite (FeS₂) roasting in a temperature range of 400–500°C, with partial oxygen pressure from 1·01 to 28·60 kPa and particle size between 12·3 and 33·0 μm, using thermogravimetric methods. The pyrite oxidation rate was significantly influenced by temperature, partial oxygen pressure and particle size. Pyrite oxidation kinetics was also analysed, and the model X=kt gave a good description of the reaction kinetics. The dependency of pyrite oxidation on partial oxygen pressure was in the order of 3/5. The intrinsic oxidation rate constants were also determined and an activation energy value of 60·5 kJ mol⁻¹ was obtained for the temperature range used in the study. The results indicate that the rate of pyrite oxidation was controlled by chemical reactions under the conditions of the experiments.

Mining activities have been a part of the history of Chile since time immemorial, generating pollution and environmental liabilities. Due to the lack of regulation, many tailings are deposited close to rivers or/and on unstable ground, near which towns have been built, generally in locations with no budget for their treatment. This study tested three plant species from Northern and Central Chile to remove total chromium, nickel, and zinc from tailings: Solidago chilensis, Haplopappus foliosus, and Lycium chilense, which complements the few existing studies on heavy metals removal with native or endemic Chilean shrubs. The experiments were conducted ex situ, and the initial and final concentrations of metals were determined in tailings and plants to obtain the removal efficiency, translocation and bioconcentration factors. Among these species, the best performance was obtained using Solidago chilensis, achieving removal efficiencies of 24% for Cr, 19% for Ni, and 17% for Zn, showing the ability to phytostabilize chromium and the higher resistance concerning the toxicity threshold. Haplopappus foliosus and Lycium chilense presented a slight tendency to stabilize chromium. Only Solidago chilensis showed little ability to extract Zn.

The volumetric mass transfer coefficients (k_La) of oxygen during sorption and desorption were analyzed using nanobubbles (NBs) of air and pure oxygen under various experimental conditions. The results showed that oxygen NBs achieved an increase in dissolved oxygen (DO) levels during absorption, reaching peaks of 30–34 mg∙L⁻¹ and stabilizing at 31.3 ± 0.2 mg∙L⁻¹, with a volumetric mass transfer coefficient of 0.105 ± 0.002 min⁻¹. In comparison, air NBs showed a lower efficiency, with peak DOs of 8∙10 mg∙L⁻¹ and k_La of 0.048 ± 0.001 min⁻¹. In desorption studies, oxygen NBs had higher DO retention, reducing from 30.0 mg∙L⁻¹ to 15.0 mg∙L⁻¹ in 300 min, with a k_La of 0.042 ± 0.003 min⁻¹, while air NBs decreased more rapidly, with a k_La of 0.028 ± 0.002 min⁻¹. When oxygen was used, k_La outperformed air in both absorption and desorption, with a higher k_La during absorption, a lower k_La during desorption, and higher stability. In addition, the results show that the residence time has an important impact on the performance of NBs, showing that the direct influence of the flow dynamics and surface/to/volume ratio influences the value of k_La. The results highlight the superior performance of oxygen NBs versus air NBs in terms of mass transfer efficiency and stability and highlight the effect of residence time and NB composition in applications requiring efficient oxygen transfer, given the promising prospects for the development of advanced aeration technologies in industrial and environmental contexts.