In the present research work, the temperature effect on the corrosion inhibition process of API 5L X60 steel in 1 M H₂SO₄ by employing three vinylimidazolium poly(ionic liquid)s (PILs) was studied by means of electrochemical techniques, surface analysis and computational simulation. The results revealed that the maximal inhibition efficiency (75%) was achieved by Poly[VIMC4][Im] at 308 K and 175 ppm. The PILs showed E_corr displacements with respect to the blank from −14 mV to −31 mV, which revealed the behavior of mixed-type corrosion inhibitors (CIs). The steel micrographs, in the presence and absence of PILs, showed less surface damage in the presence of PILs, thus confirming their inhibiting effect. The computational studies of the molecular orbitals and molecular electrostatic potential of the monomers suggested that the formation of a protecting film could be mainly due to the nitrogen and oxygen heteroatoms present in each structure.

Two hydrothermal techniques under microwave irradiation were used to synthesize γ-MnO₂ from 90°C to 150°C in 10−30 min. The first technique is based on reducing KMnO₄ with MnSO₄, and the second one involves liquid-phase oxidation between MnSO₄ and (NH₄)₂S₂O₈. The structures and morphologies of the samples were analyzed using X-ray diffraction, scanning electron microscopy, and N₂ physisorption measurements. The electrochemical properties were evaluated through cyclic voltammetry and electrochemical impedance spectroscopy. The γ-MnO₂ materials obtained by the first technique mainly exhibited nanorods with diameters of 40–60 nm, and the samples obtained by the second technique showed flower-like microspheres with diameters of 1−2 µm; each flower was composed of nanosheets with a thickness of 10−20 nm. The processing time directly depends on the size of the nanorods. The sample synthesized by the first technique at 150°C and 10 min has the highest specific surface area of up to 59.08 m² g⁻¹ and mean pore diameter of 34.11 nm. Furthermore, this sample exhibits a near-rectangular cyclic voltammetry curves and high specific capacitance of 331.3 F g⁻¹ in 0.1 M Na₂SO₄ solution at 5 mV s⁻¹ scan rate. Graphic abstract

This work focuses on the recovery of lead and silver from jarosite waste by a three-stage process: drying, roasting and reduction at 100 °C, 700 °C and 1400 °C, respectively. A flux mixture with 48 mass% CaO and 52% SiO₂ was used for the reduction stage. A gas consisting of 70 vol% CO and 30 vol% CO₂ was used as a reducing agent. To select the temperatures and the amount of flux and reducing agent, a characterization of the jarosite waste was carried out using thermogravimetry and high-temperature X-ray diffraction, as well as a thermodynamic study of the effects of the process parameters. The lead-rich metallic and slag phases were characterized by chemical analysis, SEM-EDS and XRD. In addition, the jarosite residue and the final slag were leached with an aqueous acetic acid solution to estimate their chemical stability. The results show a recovery of over 95% of the lead and silver and the formation of an environmentally friendly residual slag.

In this study, bismuth titanate (Bi₄Ti₃O₁₂) was synthesized from pure solid compounds and structurally characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The electrical properties were evaluated by measuring the electrical conductivity of Bi₄Ti₃O₁₂ at various oxygen partial pressures (pO₂ = 10⁻⁵ and 10⁻⁸ atm) and temperatures (450 °C-750 °C). The electrical conductivity behavior was assessed during the heating and cooling processes. The material activation energies were determined based on the heating curve, which displayed Arrhenius-type behavior and activation energy slope changes, which could be attributed to point defects. When the temperature was increased from 450 °C to 750 °C at oxygen partial pressures pO₂ = 10⁻⁵ atm, the electrical conductivity increased by about 62.9 %, whereas when the temperature decreased from 750 °C to 450 °C, the electrical conductivity was reduced by 35.95 %. The electrical behavior of Bi₄Ti₃O₁₂ was analyzed by establishing its electrical conductivity and chemical activity under different oxygen partial pressures and heating-cooling conditions can allow the synthesis of materials with attractive characteristics for electronic applications.

Different composites of manganese oxides (Mn_xO_y) containing sodium (Na) and silver (Ag) were synthesized by the molten salt method with various MnSO₄·H₂O/NaNO₃ (M/N) molar ratios (between 0.3 and 1), and different AgNO₃ and NaOH amounts, obtaining two groups of materials: without the addition of AgNO₃ (labeled as M/N) and with AgNO₃ (labeled as M/N-A). As for the M/N group, the system with the lowest M/N ratio yielded the highest specific capacitance (160.5 F ${\mathrm{g}}^{-1}$), attributed to the formation of Mn₃O₄ and sodium birnessite. In the M/N-A group, the 1 M/N-0.5A system, produced with M/N ratio of 1 and addition of 0.5 g of AgNO₃, exhibited the highest specific capacitance (229.1 F ${\mathrm{g}}^{-1}$), associated with the presence of Mn₂O₃, silver hollandite, and metallic Ag. This enhancement is attributed to the synergistic effects of Na⁺ and Ag⁺ ions, which improve charge transfer kinetics and electrochemical performance. It was demonstrated that decreasing the MnSO₄·H₂O/NaNO₃ ratio in the M/N group and increasing AgNO₃ content in the M/N-A group enhances the electrochemically active surface area. Galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques confirmed that the 1 M/N-0.5A system exhibited the best performance, characterized by high energy retention, stable cycling behavior, and low capacitance dispersion, indicating its strong potential as an active material for pseudocapacitor applications.

In this work, the characteristic temperatures (solidus and liquidus) of selected lead blast furnace slags were investigated using in situ high-temperature optical microscopy. The effects of the basicity of the slag (CaO/SiO₂), the Fe/SiO₂ ratio, and the Zn content were investigated. The deformation temperature associated with the rounding of the sample edges and the temperature at which 75% of the sample height decreases were experimentally considered as the solidus and liquidus temperatures, respectively. The pseudoternary phase diagrams CaO-SiO₂-Fe_0.63Zn_0.37O and FeO-Ca_0.54Si_0.46O_1.46-ZnO were calculated, along with the crystallization curves, using the thermodynamic software FactSage to estimate the characteristic temperatures and phase evolution during the cooling of the slag. The difference between the calculated and experimental solidus and liquidus temperatures was about 70 °C. The results of XRD, SEM, and DSC analysis at high temperatures showed that spinel (ZnFe₂O₄), melilite (Ca₂ZnSi₂O₇), and andradite (Ca₃Fe₂Si₃O₁₂) were the base crystals for all slag samples. The liquidus temperature increases with decreasing slag basicity (CaO/SiO₂), while the liquidus temperature increases with increasing Fe/SiO₂ ratio or Zn content.