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The use of nanofluids in enhanced oil recovery processes has gained attention due to the possibility to intensify oil recovery from mature oil fields. When nanofluids are injected into oil wells, different mechanisms are involved such as wettability alteration, reduction of interfacial surface tension, increase in the viscosity of the aqueous solution, and decrease in oil viscosity. Silica nanoparticles are extensively used for nanofluid formulations but there are important obstacles to the use of nanofluids in enhanced oil recovery. Stability is the most evident, in addition to environmental and economic aspects, and the need to design suitable large-scale production processes for nanoparticle synthesis with the required characteristics. Thus, the present study aims to evaluate oil recovery using silica-based nanofluids from various sources (natural rice husk ash, sol-gel synthesis, and commercial nanosilica) under different operational conditions. Silica nanoparticles were characterized by XRF, XRD, TEM, FTIR, specific surface area, and XPS. Nanofluids with different nanoparticles concentration were characterized by their viscosity, surface tension, zeta potential, and stability. Oil recovery from an oil-saturated sand-packed bed increased due to the nanofluid injection after secondary recovery. An additional 5–10% oil recovery is achieved after flooding due to the injection of nanofluids, proving that silica from rice husk ash has comparable efficiency to other synthetic silica nanoparticles that are used in enhanced oil recovery.

The aim of this study is to investigate the thermal behavior of Pinus wood pellets during torrefaction under different operational conditions, as well as to evaluate the potential application of the torrefied product in metallurgical processes. Torrefaction tests were carried out in an oxidizing atmosphere (245 °C) and in an inert atmosphere (270 and 290 °C) at residence times of 15 and 60 min. The results of torrefaction in inert atmosphere were also statistically evaluated. To evaluate the potential application of torrefied biomass in metallurgical processes, reactivity tests with CO2 were performed in the temperature range of 200–1000 °C. The results showed that high torrefaction temperature and residence time decreased the mass yield. Statistical analysis showed the possibility of combining high temperatures with low residence times, or vice versa, to obtain satisfactory mass yields. The experimental results showed the highest reactivity for the torrefied biomass obtained in an inert atmosphere, at 290 °C and 60 min. However, considering the mass yield and reactivity with CO2, the best torrefaction conditions for biomass with potential application in metallurgical processes were in an inert atmosphere, at 290 °C and a residence time of 15 min.

In this study, porous microspheres of TiO2 (µTiO2) were synthesized, characterized and incorporated into an acrylic paint formulation to obtain a photocatalytically active paint. In a novel approach, the antifungal properties of the µTiO2 paint were evaluated using Monascus ruber as the representative microorganism and compared to those of a photocatalyst-free paint. The photocatalytic activity of paint films was determined by methylene blue (MB) degradation under real conditions of application. High photocatalytic and antifungal activity was observed, with the microorganism culture showing the formation of growth inhibition halos, typical of materials that produce biocides that diffuse into the culture medium.

The aim of this work was to investigate the carbonation kinetics of lithium orthosilicate (Li4SiO4) by thermogravimetry and via thermodynamic simulations, using CO2 concentrations of 15 vol.% (typical of combustion gases) and 100 vol.%. Tests were performed in a thermogravimetric analyzer, in two sequential steps: (1) pre-treatment at 750 ºC with N2 and (2) thermal analysis, non-isothermal (at 10 ºC min-1 up to 1000 ºC) or isothermal (at 550 ºC, 600 ºC and 650 ºC). According to the non-isothermal results, the carbonation of Li4SiO4 occurs in the range of 450-746 ºC and the decarbonation above it. Also, it was possible to capture up to 24.9 wt.%CO2. The isothermal kinetics showed that an increase in temperature promotes an increase in the reaction rate. Yet, the adsorption capacity is limited by the thermodynamics at higher temperatures and the kinetics is slow at low CO2 concentrations.