In this work, the assessment of Azadirachta indica, Tagetes erecta, Chrysanthemum morifolium, and Lentinula edodes extracts as catalysts for the green synthesis of zinc oxide nanoparticles (ZnO NPs) was performed. The photocatalytic properties of ZnO NPs were investigated by the photodegradation of methylene blue (MB) dye under sunlight irradiation. UV-visible (UV-Vis) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Thermogravimetric (TGA), and Brunauer-Emmett-Teller analysis (BET) were used for the characterization of samples. The XRD results indicate that all synthesized nanoparticles have a hexagonal wurtzite crystalline structure, which was confirmed by TEM. Further, TEM analysis proved the formation of spherical and hemispherical nanoparticles of ZnO with a size in the range of 14–32 nm, which were found in aggregate shape; such a size was well below the size of the particles synthesized with no extract (~43 nm). ZnO NPs produced with Tagetes erecta and Lentinula edodes showed the best photocatalytic activity, matching with the maximum adsorbed MB molecules (45.41 and 58.73%, respectively). MB was completely degraded in 45 min using Tagetes erecta and 120 min using Lentinula edodes when subjected to solar irradiation.

Multilayer coatings having a thickness of 18–22 μm consisting of different Ni, Ni-B alloys and Ni-B-PTFE composite layers were produced on steel by combining electroplating with electroless dynamic chemical plating (DCP). The individual Ni layers and the multilayer coatings (Ni/Ni-B and Ni/Ni-B/Ni-B-PTFE) were characterized by scanning electron microscopy (SEM), electrochemical polarization measurements and salt spray tests. The Ni coatings presenting high corrosion resistance (6000 h, ASTM-B117) were obtained by electrodeposition from a sulfamate bath containing a samarium salt, whereas Ni-B layers of high hardness (700 to 800 HV) were produced by both methods (electroplating and DCP). Composite Ni-B-PTFE coatings (≈14% volume of PTFE) of high hardness (≈600 HV) and low friction coefficient (0.4 to 0.5) were obtained by the DCP technique. A duplex Ni(10.6 μm)/Ni-B (12μm) coating produced by electrodeposition exhibited a total hardness of 618 ± 9 HV and corrosion resistance higher than 1369 h in the salt-spray test. Combining electrodeposition with DCP produced a three-layer Ni (8 μm)/Ni-B (2.5 μm)/Ni-B-PTFE (7.8 μm) with high corrosion resistance and proper hardness as well as a low coefficient of friction.

This study presents the green synthesis and comprehensive characterization of ZnO–Ag nanocomposites using an eco-friendly approach that incorporates aqueous Tagetes erecta extract via the co-precipitation method. The research systematically evaluates the effect of silver concentration (0.1–0.5%) on material properties and dual applications: solar photocatalytic degradation of methylene blue and antibacterial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. Advanced characterization techniques, including UV-Vis, XRD, TEM, FTIR, and TGA, confirmed the successful formation of crystalline nanocomposites with spherical and hemispherical morphologies, consisting of hexagonal wurtzite ZnO and face-centered cubic Ag phases. Results demonstrate that strategic silver incorporation significantly enhances ZnO photocatalytic activity by improving charge separation and reducing recombination rates, with the ZnO–Ag (0.3%) nanocomposite exhibiting optimal performance, achieving complete methylene blue degradation within 25 min under solar irradiation. Antibacterial assays showed efficacy against the bacteria used, with a significantly stronger bactericidal effect against S. aureus than E. coli, especially for ZnO–Ag (0.2%) at a 250 μg/mL concentration. This study highlights the synergistic effect between ZnO, Ag, and bioactive compounds from Tagetes erecta, offering a sustainable approach for developing multifunctional nanomaterials with significant potential in environmental remediation and antibacterial applications.

Alizarin Red S (ARS) is a persistent anthraquinone dye whose discharge into aquatic environments represents an important concern due to its chemical stability, intense coloration, and potential ecological impact. Adsorption has emerged as one of the most practical approaches for its removal from aqueous media because of its operational simplicity, adaptability, and compatibility with low-cost and regenerable materials. This review critically examines recent progress in the adsorption of Alizarin Red S using a broad spectrum of adsorbents, including biomass-derived materials, activated carbons, carbon nanotubes, graphene-based systems, polymeric sorbents, metal oxides, metal–organic frameworks, hydrogels, magnetic composites, and hybrid nanostructures. Particular attention is given to the relationship between adsorbent composition, surface chemistry, porosity, functional groups, and adsorption performance. The effects of pH, adsorbent dosage, initial dye concentration, contact time, temperature, and coexisting ions are discussed as key factors controlling dye uptake, equilibrium behavior, and removal efficiency. The reviewed studies indicate that ARS adsorption is commonly governed by electrostatic attraction; hydrogen bonding; π–π interactions; surface complexation; pore diffusion; and, in some systems, dye–metal complex formation. Langmuir and Freundlich isotherms, together with pseudo-second-order kinetics, are the most frequently reported models. Despite significant laboratory-scale advances, challenges remain regarding adsorbent regeneration, selectivity in complex matrices, long-term stability, cost-effective synthesis, and scale-up. Future research should prioritize real wastewater validation, multicomponent systems, circular adsorbent design, computational modeling, machine learning-assisted optimization, and life cycle assessment to support the transition of ARS adsorption technologies toward practical wastewater treatment applications.