Although their exceptional re-passivation ability, Al-alloys are susceptible to corrosion due to the amphoteric nature of the alumina passivation films. This issue is exacerbated by the disruption of these films by intermetallics on the surfaces of highly doped ones, like AA2024-T3 aircraft alloy. The combination of anodized aluminium oxide (AAO) and cerium conversion coatings (CeCC) shows promise as a coating primer. However, the defective structures of CeO2 and Al2O3 require additional sealing. This research proposes sealing the CeCC/AAO layer by boiling it for 10 minutes in two relatively neutral Lourier buffers, adjusted to pH 7.75, and in a mixture of them. The samples underwent a series of analyses to compare the impact of the sealing procedure on surface topology, properties (e.g., colour and wettability on two samples from each set), and corrosion protective ability. It was assessed after 24 hours of exposure to 3.5 % NaCl model corrosive medium on six samples from each set. The assessments included electrochemical impedance spectroscopy (EIS) and potentiodynamic scanning (PDS) techniques. The results indicate that the borate buffer improves the corrosion protection of the coating primers more effectively than the phosphate and mixed ones.

The dependence of the reaction rate on the solution layer thickness discovered in a previous work could be a powerful tool for investigating photocatalytic reactions. A reduction of the apparent rate constant with the growth of the dye concentration was found using this dependence. This decrement follows a hyperbolic law. This dependence is explained based on the observed increment of the solution conductivity. In addition, it is confirmed experimentally that the reaction rate decreases with the solution depth growth. The possibility of independent determination of the reaction rate constant and the adsorption equilibrium constant has been discussed. Additionally, it is demonstrated that the vessel’s reflective bottom could increase the chemical reaction rate. The reason why other authors have not yet reported this effect is also discussed.

The model for photodegradation with a modified rate constant that was developed and presented in previous study, was generalized for the application of ZnO-based photocatalyst in both thin film and powder form. The applicability of the model was proved on methylene blue discoloration on both types of photocatalysts. The photocatalytic reaction rate was found to be dependent on the depth of the solution in case of small depths for this photocatalyst. This correlataion was valid in both high and low transparency. In addition, the impact of the solution pH on the model pollutant decomposition rate was defined.

The present research is dedicated to the systematic characterization of the surface characteristics of AA2024-T3 specimens, after the formation of Anodic Aluminium Oxide (AAO) layer, deposition of a Ceruim Conversion Coating (CeCC) and combination of these methods. The latter procedure was performed at two temperatures (20°C and 50°C). The investigations comprised combined AAO/CeCC coating primers, as well. All the obtained protective layers were subjected to systematic evaluations for determination of their colour characteristics, wettability and topology. The latter, including the layer thickness, was observed by both Optical Metallographic (OMM) and Scanning Electron (SEM) Microscopy. The outcome analysis of this study provides an additional contribution to the contemporary discussion on the formation of combined AAO/CeCC coating primers.

New bulk chalcogenides from the system (GeTe6)1-xCux, where x=5, 10, 15 и 20 mol %, has been synthesized. The structure and composition of the materials was studied using X-ray powder diffraction (XRD) and energy dispersive spectroscopy (EDS). Scanning electron microscopy (SEM) has been applied to analyze the surface morphology of the samples. Some thermal characteristics as glass transition, crystallization and melting temperature and some physicochemical properties as density, compactness, molar and free volume were also determined. The XRD pattern shows sharp diffraction peaks indicating that the synthesized new bulk materials are crystalline. The following four crystal phases were determined: Te, Cu, CuTe и Cu2GeTe3. The results from the EDS confirm the presence of Ge, Te and Cu in the bulk samples in a concentration in good correspondence with those theoretically determined. A layered thin film material based on the synthesized new Ge14Te81Cu5 chalcogenide, which has the most flexible structure, and the azo polymer PAZO has been fabricated, and the kinetic of the photoinduced birefringence at 444 nm has been measured. The results indicate an increase in the maximal induced birefringence for the layered structure in comparison to the non-doped azo polymer film.

The influence of suspension depth and pollutant concentration on the rate and efficiency of photocatalytic degradation was investigated in aqueous TiO₂ suspensions using methyl orange (MO) as a model pollutant. Both the reaction rate and the efficiency increased by more than one order of magnitude upon a relatively small decrease in suspension layer thickness. The reaction rate exhibited a complex N-shaped dependence on dye concentration, deviating from the monotonic behavior predicted by the Eley–Rideal and Langmuir–Hinshelwood mechanisms, as well as from the relationship derived in our previous study. To elucidate the origin of this behavior, nanoparticle aggregation was examined by sedimentation kinetics, low-acceleration centrifugation, and scanning electron microscopy (SEM). The results suggest that the interplay between enhanced dye adsorption and the reduction in the available photocatalyst surface area due to aggregation leads to the appearance of a maximum in the concentration dependence of the reaction rate. The relationship between reaction rate and photocatalytic efficiency was also analyzed. Although both parameters are correlated, efficiency values strongly depend on the selected reaction time interval, which complicates direct comparison between studies employing different experimental protocols. Consequently, the reaction rate appears to be a more reliable parameter for describing photocatalytic kinetics.