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In this work, ordered mesoporous silica MCM-41 was prepared by hydrothermal synthesis using industrial-grade sodium silicate (Na₂SiO₃) as silica source, hexadecyltrimethyl-ammonium bromide (CTAB) as template agent and ethyl acetate as pH regulator. The influence of CTAB/SiO₂ molar ratio, reaction time, aging temperature, and co-surfactant type on the structural and morphological properties of the obtained silica was studied. The roducts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption-desorption isotherms. Ordered mesoporous MCM-41 silica was obtained at 80 °C by using a range of CTAB/SiO₂ molar ratio from 0.35 to 0.71 and reaction times up to 72 h and isopropanol (<em>i</em>-PrOH) as cosurfactant.

Beneficiation of industrial wastes, such as mine tailings (MTs), through development of alternative eco-friendly geopolymer binders for construction composites offers a twofold environmental benefit, as it reduces the demand for cement and it increases the sustainability of industrial processes by creating a value-added product from an industrial byproduct. While MTs have the requisite composition for use as a geopolymer precursor, they are often low-reactive. This study explored the effect of Class C Fly Ash (FAc) on the geopolymerization of low-reactive gold MTs. A 10 M sodium hydroxide (NaOH) solution was used as the alkaline activator with four different concentrations of FAc (5, 10, 15 and 20 wt.%). The results indicated that the combination of FAc with the low-reactive gold MTs improved the physicochemical stability of the final geopolymerized samples, with a 95–120% increase in compressive strength, compared to the geopolymer samples of only low-reactive gold MTs. Although some of the strength improvement could be attributed to geopolymerization of the FAc itself, the presence of the FAc also improved the reactivity of the MTs, increasing the geopolymer production of the MTs. This study documents the positive effects of the FAc on gold MTs with low-calcium content and their conversion into sustainable inorganic composite geopolymers for the construction field.

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Hydrophilization of carbon nanofibers (CNFs) was achieved using plasma polymerization of acrylic acid. Transmission electron microscopy (TEM) and spectroscopy techniques were used to assess the structural changes and type of chemical groups grafted on CNFs during plasma treatment. Electron energy loss spectroscopy analysis showed a decrease of sp2 bonds and an increase of sp3 bonds coming from the thin film of polyacrylic acid deposited on CNFs during the plasma treatment. X‐ray photoelectron spectroscopy (XPS) corroborated that the sp2/sp3 ratio of the treated CNFs decreased from 3.95 to 1.14. Also the presence of carbonyl and carboxyl groups were identified by XPS, whose presence promotes the hydrophilic character of CNFS and their dispersion in water. An amorphous structure on the surface of treated CNFs, which corresponds to the nanocoating of polyacrylic acid deposited by plasma, was observed by TEM.