Multifunctional materials have become an important research subject in recent years. Zinc oxide nanoparticles (ZnO NP) deposited on iron oxide (Fe₃O₄) allow to obtain material with photocatalytic and magnetic properties. The mass share of Fe₃O₄in the composite was 30%. Saturation magnetization for this sample was about 9.5 emu/g. The use of magnetic material allows to recover the photocatalyst after the photodegradation process and reuse it. The possibility of recovery of Fe₃O₄nanoparticles with a magnet was estimated at 94.80%, while the recovery of Fe₃O₄/ZnO achieved 83.91%. The effects of the type of dyes (Methylene Blue, Methyl Orange, Quinoline Yellow, Eriochromic Black T and Trypanic Blue) on their photodegradation efficiency in terms of molar mass of the dye, the solvent in which the processes were carried out and the type of dye charge were investigated. The photocatalytic material showed higher photodegradation activity of dyes while increasing their molar mass. ZnO NPs deposited on Fe₃O₄ presented 95.61% photocatalytic efficiency against Trypan Blue and 63.02% against Methylene Blue. Increasing the surface area of the catalyst to 39 m²/g and the presence of micro-, meso- and macropores had a positive effect on the sorption process of dyes, especially those of larger sizes, allowing their degradation in the photodegradation process.

Natural deep eutectic solvents (NDESs), as a new type of green solvent, are used in many fields, including industry in extraction processes, medicine, pharmaceuticals, metallurgy, electrodeposition, separations, gas capture, biocatalysis and nanotechnology. Mainly due to their properties, such as simple preparation, environmental friendliness, biocompatibility and multifunctionality, they are being used in various fields of industry. This review aims to provide insight into the applications of natural deep eutectic solvents, specifically in nanotechnology processes. It focuses on the description of NDES and how their physicochemical properties are used to obtain functional nanomaterials, including metals, metal oxides and salts. It highlights how the use of NDESs to obtain a wide range of inorganic nanoparticles enables the elimination of disadvantages of traditional methods of obtaining them, including reducing energy consumption and functionalising nanoparticles in situ. In conclusion, recent advances and future directions in the development and applications of NDESs in nanotechnology are discussed with the aim of identifying unexplained scientific questions that can be investigated in the future.

Silver and copper nanoparticles (AgNPs and CuNPs) have attracted worldwide attention due to their unique antimicrobial properties. Ethanol and water extracts of hawthorn fruit were chosen to prepare AgNPs and CuNPs. The effects of the pH, contact time, temperature of the solution, type of precursor of metal ions and type of hawthorn extract on the size distribution of particles were studied. The monodispersed and stable AgNPs and CuNPs were prepared with an average size of 60 nm and 200 nm, respectively. Total phenolic content and the anthocyanin content of extracts were determined. The antimicrobial activities of AgNPs and CuNPs were carried out with a series of microbial assays.

ZrO₂–ZnO nanoparticles with different mass concentrations of ZrO₂ (1%, 5%, 10%, 20%) were prepared using a two-stage precipitation method with microwave irradiation. The ZrO₂–ZnO with 10% of ZrO₂ had the highest photocatalytic activity. The obtained material was characterised using XRD, which confirmed a high crystal structure in the synthesised material, and transmission electron microscopy (TEM) analysis, which depicted that micro and nano needle-shaped particles had been obtained and that irregularly shaped nanoparticles were present on the surface of those particles. TEM–EDX analysis confirmed the presence of both ZnO and ZrO₂ in the product. FT-IR analyses showed that the positions of peaks related to Zn–O and Zr–O absorption bands did not change in ZrO₂–ZnO NPs. The initial concentration of Methylene Blue (MB), the pH of the solution, and the mass of the photocatalyst were investigated to determine the photocatalytic efficiency of the material and the degree of removal of the MB. The highest efficiency (97%) was obtained in the following conditions: 30 mg/dm³ of the MB solution, pH 9 and 70 mg ZrO₂–ZnO after 30 min of reaction time under UV irradiation.