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The growing demand for petroleum products and the natural decline of well’s pressure during oil production turned the oil industry’s focus onto the development and improvement of enhanced oil recovery (EOR) techniques. Nanotechnology and nanomaterials may increase oil recovery rates through nanofluid flooding applications. In this scenario, a nanofluid containing Fe3O4 nanoparticles (NPs) with the ability to carry surfactants such as cetyltrimethylammonium bromide (CTAB) was synthesized; a synergistic effect was observed when used for wettability modification of calcite fragments, reaching 80% of contact angle reduction. Raman and XPS analysis revealed that Fe3O4 NPs were able to selectively remove smaller and more disordered asphaltene molecules that present a less planar aromatic core, as indicated by the D/G Raman peaks intensity ratio and consequently weaker adsorption on the calcite surface. The presence of CTAB improved nanoparticle mobility in limestone porous medium during flooding experiments and its stability in saline solutions with high concentrations of divalent cations, while the presence of nanoparticles improved the wettability modification. Furthermore, the nanofluid can slow down CaCO3 scale formation, contributing to the flow assurance during the nanoflooding process. These combined effects improve nanofluid efficiency in tertiary oil recovery as observed during the flooding tests in an unconsolidated porous medium, giving a recovery factor up to 60%.

Two-dimensional materials (2DM) have attracted much interest due to their distinct optical, electronic, and catalytic properties. These properties can be tuned by a range of methods including substitutional doping and,...

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This work examines the leaching of printed circuit boards (PCBs) from cell phones in aqueous solutions containing HF + H 2 O 2 or HF + NaClO under mild experimental conditions. The PCBs were not ground but were previously treated with 6 mol L -1 NaOH at 50 o C for 1 h to remove their soldering mask. , respectively. The processing of the solid residue is also described in detail. It was leached with water at ~90 o C followed by HNO 3aq. at 25 o C. Lead, palladium and silver were recovered in this order, leaving gold as final solid. After 1 h at [35][36][37][38][39][40] o C, 5 mol L -1 HF + 0.3 mol L -1 NaClO mixtures leached the base metals, copper, gold and palladium. Gold was recovered by liquid-liquid extraction with methyl isobutyl ketone. Silver precipitated as chloride. This salt was isolated by leaching with NH 3aq . Loss of fluoride ions (as HF) was below 0.5 wt.% after leaching and handling the solid residue.