The main goal of wastewater treatment is to significantly reduce organic compounds, micronutrients (nitrogen and phosphorus) and heavy metals and other contaminants (pathogens, pharmaceuticals and industrial chemicals). In this work, the efficiency of removing different contaminants (COD, NO₃⁻, NO₂⁻, NH₄⁺, PO₄³⁻, SO₄²⁻, Pb²⁺, Cd²⁺) from synthetic wastewater was tested using five different yeast strains: Kluyveromyces marxianus CMGBP16 (P1), Saccharomyces cerevisiae S228C (P2), Saccharomyces cerevisiae CM6B70 (P3), Saccharomyces cerevisiae CMGB234 (P4) and Pichia anomala CMGB88 (P5). The results showed a removal efficiency of up to 70% of COD, 97% of nitrate, 80% of nitrite, 93% of phosphate and 70% of sulfate ions for synthetic wastewater contaminated with Pb²⁺ (43 mg/L) and Cd²⁺ ions (39 mg/L). In contrast, the results showed an increase in ammonium ions, especially in the presence of Pb²⁺ ions. The yeast strains showed a high capacity to reduce Pb²⁺ (up to 96%) and Cd²⁺ (up to 40%) ions compared to the initial concentrations. In presence of a crude biosurfactant, the removal efficiency increased up to 99% for Pb²⁺ and 56% for Cd²⁺ simultaneously with an increase in yeast biomass of up to 11 times. The results, which were obtained in the absence of aeration and in neutral pH conditions, proved a high potential for practical applications in the biotreatment of the wastewater and the recovery of Pb and Cd ions, with a high benefit–cost ratio.

This paper presents the obtaining and characterization of recycled polypropylene/strontium ferrite (PP/SrFe₁₂O₁₉) polymer composite materials with applications in the electromagnetic shielding of vehicle interiors (mainly automotive electronics—carcasses) from the electromagnetic radiation emitted mainly by exterior sources—electrical lines and supply sources—in terms of the development of the new electrical vehicles. With this aim, suitable polymer composite materials were developed using SrFe₁₂O₁₉ filler in two forms (powder and concentrate). The recycled PP polymer and composite materials with a PP/SrFe₁₂O₁₉ weight ratio of 75/25 and 70/30 were obtained in two stages, i.e., pellets by extrusion and samples for testing through a melt injection process. The characterization of the obtained materials took into account the requirements imposed by the desired applications. It consisted of determining the mechanical and dielectric properties, and microstructure analyses, along with the determination of the resistance to the action of a temperature of 70 °C, which is higher than the temperatures created during the summer inside vehicles. The performance of these materials as electromagnetic shields was assessed through functional tests consisting of the determination of magnetic permeability and the estimation of the electromagnetic shielding efficiency (SE). The obtained results confirmed the improvement of the mechanical, dielectric, and magnetic properties of the PP/SrFe₁₂O₁₉ composites compared to the selected PP polymers. It is also found that all the composite materials exhibited reflective shielding properties (SE_R from −71.5 dB to −56.7 dB), with very little absorption shielding. The most performant material was the composite made of PP/SrFe₁₂O₁₉ powder with a weight ratio of 70/30. The promising results recommend this composite material for potential use in automotive shielding applications against electromagnetic pollution.

Ultra-high-molecular-weight polyethylene (UHMWPE) matrices containing low-density polyethylene (LDPE), hydroxyapatite (HAp) as filler, and rosemary extract (RM) as stabilizer were investigated for their qualification for long-term applications. The significant contributions of the blend components were analyzed, and variations in mechanical properties, oxidation strength, thermal behavior, crystallinity, and wettability were discussed. SEM images of microstructural peculiarities completed the introspective survey. The stability improvement due to the presence of both additives was an increase in the total degradation period of 67% in comparison with an unmodified HDPE/UHMWPE blend when the materials were subjected to a 50 kGy γ-dose. There was growth in activation energies from 121 kJ mol⁻¹ to 139 kJ mol⁻¹ when HAp and rosemary extract delayed oxidation. The exposure of samples to the action of γ-rays was found to be a proper procedure for accomplishing accelerated oxidative degradation. The presence of rosemary extract and HAp powder significantly increased the thermal and oxidation resistances. The calculation of material lifetimes at various temperatures provided meaningful information on the wearability and integrity of the inspected composites.

The main objective of this study was to develop a high-entropy alloy (HEA) derived from the Co_xCrFeNiTi HEA system (x = 0.5, 1) for protective coatings using the magnetron sputtering method. In order to produce the high-entropy alloy targets required for the magnetron sputtering process, mechanically alloyed metallic powders were consolidated via spark plasma sintering (SPS). The microstructural analysis results of the HEA mixture presented morphology changes after 30 h of alloying, with the particles presenting uniform polygonal shapes and dimensions. Subsequently, 316L stainless steel (SS) specimens were coated via magnetron sputtering, comparing their composition with that of the sputtering targets used for deposition to establish stoichiometry. Microstructural analyses of the SPSed HEAs revealed no defects and indicated a uniform elemental distribution across the surface. Furthermore, the CoCrFeNiTi equiatomic alloy exhibited a nearly stoichiometric composition, both in the coating and the sputtering target. The XRD analysis results indicated that amorphous coatings were obtained for both Co_0.5CrFeNiTi and the CoCrFeNiTi HEA, and nanoindentation tests indicated that the CoCrFeNiTi HEA coating presented a hardness of 596 ± 22 HV, compared to the 570 ± 19 HV measured for Co_0.5CrFeNiTi, suggesting an improved wear resistance.

Steel surface protection with hard coatings is essential in metalworking, yet developing high-performance coatings is challenging. TiAlSiN coatings grown on various substrates using commercial targets have been extensively studied, but consistent data on their properties are lacking. This study focused on TiAlSiN single layers (SL) and TiAlSiN/TiN bilayers (BL), with an 800 nm thick TiAlSiN top layer and a 100 nm thick TiN mid layer. These coatings were grown on C120 tool steel discs via reactive DC magnetron sputtering using TiAlSi 75–20–5 at.% and Ti targets fabricated in-house through spark plasma sintering. The stability of coatings was assessed after thermal treatment (TT) in air at 800 °C for 1 h. SEM analysis revealed a columnar microstructure with pyramidal grains in the SL and BL coatings, and coarser pyramidal and prismatic grains in both TT coatings. EDS analysis showed a decrease in Ti, Al, Si, and N content after annealing, while O content increased due to oxide formation. High indentation hardness (9.19 ± 0.09 GPa) and low effective elastic modulus (148 ± 6 GPa) were displayed by the BL TT coating, indicating good resistance to plastic deformation and better load distribution. The highest fracture toughness was noted in the BL TT coating (0.0354 GPa), which was 16.4 times greater than the steel substrate. Better scratch resistance and low coefficient of friction (COF ≤ 0.35) were exhibited by both TT coatings. Tribological tests showed a mean COF of 0.616–0.773, comparable to the steel substrate (0.670). The lowest corrosion current density (0.1298 µA/cm²), highest polarization resistance (46.34 kΩ cm²), and a reduced corrosion rate (1.51 µm/year) in a 3.5 wt.% NaCl solution was also exhibited by the BL TT coating. These findings indicate TiAlSiN/TiN films as effective protective coatings for tool steel surfaces.

The European methodology for plastics, as a feature of the EU’s circular economy activity plan, ought to support the decrease in plastic waste. The improvement of recycled plastics’ economics and quality is one important part of this action plan. Additionally, achieving the requirement that all plastic packaging sold in the EU by 2030 be recyclable or reusable is an important objective. This means that food packaging materials should be recycled in a closed loop at the end. One of the most significant engineering polymers is polyethylene terephthalate (PET), which is widely used. Due to its numerous crucial qualities, it has a wide variety of applications, from packaging to fibers. The thermoplastic polyolefin, primarily polyethylene and polypropylene (PP), is a popular choice utilized globally in a wide range of applications. In the first phase of the current experiment, the materials were obtained by hot pressing with the press machine. The reinforcer is made of Al nanopowder 800 nm and Fe nanopowder 790 nm and the quality of the recycled polymer was examined using Fourier transform infrared spectroscopy (FTIR), a scanning electron microscope (SEM), and differential scanning calorimetry (DSC). From DSC variation curves as a function of temperature, the values from the transformation processes (glass transition, crystallization, and melting) are obtained. SEM measurements revealed that the polymer composites with Al have smooth spherical particles while the ones with Fe have bigger rough spherical particles.