Fermentation at high temperatures may be a viable alternative for ethanol production, especially in tropical climate regions. This work describes the evaluation of ethanol production through extractive fermentation at high temperatures using thermotolerant Kluyveromyces marxianus. An experimental design was applied to assess the effect of temperature on the ethanol removal process by CO₂ stripping. Subsequently, kinetic modeling of conventional batch ethanol fermentation at high temperatures was performed, and the hybrid Andrews−Levenspiel model was found to be suitable for describing the kinetics of this process. Experiments were conducted to evaluate ethanol production at high temperatures using thermotolerant yeast, specifically evaluating the effects of different specific CO₂ flow rates (ϕ = 1.0, 1.5, and 2.0 vvm) on ethanol stripping. The results indicated that in all the extractive fermentations conducted with K. marxianus, there was faster substrate uptake and earlier substrate exhaustion compared to conventional fermentation. Significant ethanol removal by stripping was achieved using a CO₂ flow rate of 1.0 vvm (EF_HT1), and complete substrate consumption was observed by the end of 12 h of fermentation. This result highlights the positive effect of temperature on ethanol entrainment. In addition, integrating the CO₂ stripping technique with high-temperature fermentation (T = 40 °C) improves process efficiency with a lower gas flow rate. This is advantageous, especially for industrial-scale applications, as it can reduce equipment costs associated with the CO₂ feed.

Candiota city, in the south of Brazil, is located near the largest reserves of mineral coal of the country. This coal is used for thermoelectric power generation. The extraction of coal from open-cut mines involves operations may generate at least some particulate matter into the atmosphere. These particles retained on the surface of metallic structures exposed to the atmosphere, may adsorb gases such as CO, CO2, SO2 and NO, which, in combination with humid air form corrosive substances, such as HNO3and H2SO4. This paper aims to evaluate the influence of Candiota coal on the corrosion of buried steel structures and exposed to atmosphere containing particulate matter from coal combustion. The coal sample was characterized by SEM (scanning electron microscopy), thermogravimetric analysis (TGA), surface area analysis (BET method), electrical conductivity (EC) analysis, FTIR and Raman spectroscopy. Corrosion was simulated by exposure of steel samples to coal particles and thermoelectric industrial atmosphere. Electrochemical tests of solutions leached from the coal were conducted by voltammetry to evaluate the soluble compounds corrosiveness. The corrosion rate was determining following the technical standard ASTM G1-90. Localized attacks and corrosion products formations were detected in API 5L Grade B steel exposure to coal. The average corrosion rate for the samples in direct contact to the pulverized coal was 0.15 mm/year, while in samples exposed to the atmosphere from industrial power plant was 0.30 mm/year. It is concluded that API 5L Grade B steel metal structures, exposed to atmospheres rich in Candiota coal and its derivatives, must be properly protected and monitored to avoid future damage caused by corrosion.