The effect of particle size and sintering temperature of the mixtures of kyanite and metallic aluminum related to the thermal transformation of kyanite into primary mullite and free silica was studied. In addition, the reaction between α‐Al₂O₃ (in situ produced by aluminum oxidation) and the silica was obtained in cristobalite structure from kyanite to obtain secondary mullite. The kyanite powders were milled by 0.5, 3, 6, and 12 hours and then were mixed with aluminum powder, which were previously milled by 3 hours. After that, the powders were characterized by X‐ray diffraction technique (XRD), scanning electronic microscopy (SEM), differential thermal analysis (DTA), and thermogravimetric analysis (TGA), and the particle size was determined in a centrifugal analyzer particle size Shimadzu model SA‐CP4. The mixed powders were pressed uniaxially into cylindrical samples (compacts), and then sintering was conducted at 1100, 1200, 1300, 1400, 1500, and 1600°C; these samples were characterized by XRD, SEM, and thermodilatometry analysis (TD); density and open porosity measurements were performed by the Archimedes method. The samples were thermally etched to observe the microstructure, which consisted of mullite equiaxial grains contained in a glassy phase. It was observed that the nonmilled kyanite mineral becomes into mullite plus silica at temperatures between 1400 and 1500°C. When the particle size was reduced at sizes less than 1 µm, the transformation temperature was low until 200°C; the X‐ray patterns of the sintered samples at 1400°C, ground for 6 hours, showed mullite peaks with small reflections of cristobalite and α‐Al₂O₃, and these samples exhibited high density and low open porosity.

The global problem of water scarcity is exacerbated by the continued contamination of potable water sources. This preliminary study investigates the potential of a hazardous industrial jarosite waste to adsorb As(V) and Cr(III) from contaminated waters. The results showed that this mining waste effectively adsorbed both As(V) and Cr(III), demonstrating its potential as a low-cost and sustainable solution for water remediation along with the use of a hazardous waste that also contaminates. The adsorption process was optimized, and the effects of various parameters on the adsorption capacity were investigated. The findings of this study suggest that the use of toxic mining residues in porous concrete could provide a promising approach for the removal of toxic heavy metals from polluted water sources, contributing to the development of more sustainable and environmentally friendly water treatment technologies. A maximum adsorption of 90.6% of As(V) and 96.3% of Cr(III) was achieved, and it was verified that the industrial jarosite initially contained about 0.44% As, which was later leached during decomposition; again, the industrial jarosite was able to re-adsorb both As(V) and Cr(III).

In this study, the synthesis and structural evolution of pure BaTiO₃ and BaTiO₃ co-doped with La³⁺ and Bi³⁺, produced using the ball milling method and heat treatment, were analyzed. The starting materials included chemically pure precursor powders of BaCO₃, TiO₂, La₂O_3, and Bi₂O₃. Stoichiometric calculations were performed using the Ba_1-3xLa_2xTi_1-3xBi_4xO₃ mechanism with concentrations x = 0.0, 0.0025, 0.0045, 0.006, 0.01, and 0.05 (mol %). The structural and morphological evolution of the samples was characterized by x-ray diffraction (XRD), Rietveld refinement, and high-resolution scanning electron microscopy (HRSEM-EDS). XRD and Rietveld refinement results indicated a tetragonal ferroelectric phase for samples with x ≤ 0.006. As doping levels increased, a peak disappearance was observed, corresponding to a phase transformation from tetragonal to cubic at x = 0.01. Additionally, a cubic secondary phase, BaBiO₃, was detected at x = 0.05, indicating that the maximum solubility of La³⁺ and Bi³⁺ ions in BaTiO₃ was exceeded at this concentration. The concentration x = 0.0025 was found to exhibit the maximum tetragonality among the samples studied, with a value of 1.0087, greater than the tetragonality for pure BaTiO₃, 1.0083. The HRSEM-EDS analysis revealed that for samples with x ≤ 0.006, the microstructure consisted of faceted shape grains with mean grain size in the range of 362.5 nm–488.3 nm. Punctual microanalysis and elemental distribution mapping of the doped samples showed that the grains were composed of Ba, Ti, O, Bi, and La, which were homogeneously distributed, confirming the incorporation of the dopant elements into the BaTiO₃ structure.

La³⁺/Bi³⁺ co-doped BaTiO₃ ceramics were synthesized via ball milling followed by heat treatment at 1200 °C according to the Ba_1−3xLa_2xTi_1−3xBi_4xO₃ formula, with dopant levels ranging from x = 0.0 to 0.006. X-ray diffraction and Rietveld refinement confirmed a ferroelectric tetragonal phase for all compositions, with the highest tetragonality (c/a = 1.009) observed for x = 0.001 exceeding that of pure BaTiO₃ (1.0083). High-resolution electron microscopy analysis revealed faceted particles with mean sizes between 362.5 nm and 488.3 nm. Low-doped samples (x = 0.001 and 0.002) exhibited higher permittivity than undoped BaTiO₃, with the maximum dielectric constant (ε_r = 2469.0 at room temperature and 7499.7 at the Curie temperature) recorded for x = 0.001 at 1 kHz. At x = 0.006, minimal permittivity variation indicated a stable dielectric response. A decrease in the Curie temperature was observed with increasing doping levels, indicating a progressive tendency toward the cubic phase. Critical exponent γ values (0.94–1.56) indicated a sharp phase transition for low-doped samples and a diffuse transition for highly doped BaTiO₃. These results showed that La³⁺/Bi³⁺ co-doping effectively tunes the structural and dielectric properties of BaTiO₃ ceramics.

Extractive metallurgy has recently turned its attention to waste treatment for the recovery of precious metals through innovative metallurgical processes, such as ion flotation. This work studied the influence of several chemical and physical factors, such as the concentration of xanthate [x], frother agent [e], dithiophosphate [xl], pH, superficial gas velocity Jg, percentage of gas holdup Eg, bubble diameter (Db) calculated with the drift flux model, and the type of sparger, in the efficiency of silver(I) recovery by the ion flotation technique in sub-aerated cells. The results obtained indicate a 90.7% v/v recovery of silver(I) under conditions of 3.77 × 10⁻⁴ M [x], 1.25 × 10⁻⁴ M [e], Jg 0.5 cm/s, Jl 0.19 cm/s, Eg of 4.1% v/v, and Optimal Db of 0.11 cm, with a rigid bubble generator, achieving an apparent flotation kinetics of 4.16 1/min. The use of combinations [x]–[xl] achieve a silver(I) recovery of 86.9% with a Jg of 1.0 cm/s. The best recovery efficiencies achieved 93% w/w silver(I) are with pH 8.0, [e] of 1.25 × 10⁻⁴, Jl of 0.19 (cm/s) and a rigid sparger compared to a flexible one.

The results of the effect of the three Ba:Ti molar ratios (MR) (1:1, 2:1, 4:1) and four sintering temperatures (1250, 1275, 1300, 1325 °C) on the structural and electrical properties of BaTiO₃ (BT)-type ceramics synthesized by the hydrothermal method are shown. The BT phase formed was analyzed by x-ray diffraction (XRD), Raman spectroscopy (RS), dielectric and ferroelectric measurements and high-resolution scanning electron microscopy (HRSEM). For the samples synthesized using a Ba:Ti MR of 4:1 and at all sintering temperatures analyzed, XRD results confirmed the presence of the tetragonal ferroelectric phase, BT. In the same way, these results corroborated the results obtained by the RS technique. Dielectric properties measured at 100 kHz and 1 MHz over a temperature range of 30 °C–200 °C indicated a relative permittivity value of 4280 at 1 MHz and 4200 at 100 KHz at a Curie temperature of 110 °C in both cases for the sample synthesized at with a Ba:Ti MR ratio of 4:1 and sintered at 1300 °C. Ferroelectric measurements for the samples showed a best remnant polarization (Pr) of 3.5 µC/cm² for the sample synthesized with a Ba:Ti MR ratio of 4:1 and sintered at 1325 °C. The HRSEM results showed grains composed of Ba, Ti, and O homogeneously distributed in the BT structure, and a trend of increasing average grain size with increasing sintering temperature was observed.