In the present study we have analyzed effects of Ag + ions doping on energetic profiles of nanophosphors materials based on fluorapatite crystal system. The UV radiation absorption and luminescence properties of monophase fluorapatite (FAP) and Ag + doped fluorapatite (AgFAP) nanomaterials obtained by neutralization method were investigated using the photoluminescence spectrophotometry. The excitation-emission profiles of nanomaterials were analyzed statistically by MCR-ALS method and number of fluorophores was extracted. FAP lattice absorbed light at 350 nm in the UVA part of spectrum, and with increasing concentration of Ag + ions new absorption maximum appeared at 270 nm in the UVC part. Fluorescence of FAP nanoparticles was in violet region of visible part of the spectrum, with a red shift to the green region when Ag + was doped in lattice. MCR-ALS analyses of fluorescence spectra confirm formation of two maxima, at 484 and 505 nm, as a consequence of Ag + ions doping in FAP lattice at Ca1 (4f) sites. The results of quantum chemical calculations showed that an Ag + ion is stronger bonded to the binding site 1 (−1352.6 kcal/mol) than to the binding site 2 (−1249.0 kcal/mol). Considering that AgFAP1 nanopowder absorbs photons over all part of UV radiation spectrum, this material might be used as potential radiation protective nanomaterial.
Coupled substitution of fluorapatite (FAP) crystal lattice plays an important role in the engineering of optically active nanomaterials. Uniform fluorapatite nanopowders doped with praseodymium (Pr3+) and carbonate (CO32−) ions have been successfully synthesized by precipitation method under room temperature (25 °C). The structural, morphological, chemical and optical properties of monophase material were characterized by X-ray diffraction (XRD), Fourier Transform Infrared and Far Infrared Spectroscopy (FTIR and FIR, respectively), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS), Transmission Electron Microscopy (TEM) and Photoluminescence Spectroscopy (PL). Coupled substitution of FAP crystal lattice with Pr3+ and CO32− reduces the crystallite size with a constant c/a ratio of 1.72. FTIR study showed that synthesized nanopowders were AB-type CO32− substitution, and FIR study revealed new Pr–O vibrations. TEM analysis was found that synthesized nanopowders were composed of irregular spheres in the nanometer range. The fluorescence of FAP nanoparticles was in the violet-blue region of the visible part of the spectrum. When Pr3+ was doped in a lattice, the violet-blue emission becomes sharper due to reabsorption. MCR–ALS analyses of fluorescence spectra indicated the shift of the maximum to the blue color with the increase in the concentration of Pr3+ ions. Additionally, luminescent nanopowders demonstrated significant antibacterial activity against Escherichia coli. As the obtained nanoparticles showed a good absorption of ultraviolet A light and reabsorption of blue-green luminescence, they are suitable for further development of optically active nanomaterials for light filtering. Optically active PrCFAP nanopowders with antibacterial properties may be promising additives for the development of multifunctional cosmetic and health care products.
Scientists discovered plastic in the early 1900s, but didn't realize the detrimental effects its fragmentation could have on the environment 100 years later. In particular, nanoplastics (NPs) particles ranging in size from 1 to 100 nm can cause major problems in the living world due to their high specific surface area for the adsorption other polluting substances from water, and their further bioaccumulation through the food chain. There is no distinctive method to identify, characterize, and quantify nanoplastics in aquatic environments. Although many of the methods developed to study microplastics are not directly applicable to nanoplastics, conventional methods of characterizing nanoplastics are usually tedious because they study individual nanoparticles in isolation. Since nanoplastics resulting from the decomposition of microplastics have different properties than engineering plastic nanoparticles, new techniques need to be developed to help us better understand the seriousness of the nanoplastic problem. Nanoplastic can be isolated from the water environment by a combination of filters and ultracentrifugation. A recent publications states that combining microscopy and spectroscopy, supported by chemometric techniques, will alow a better understand he behavior of nanoplastic particles in the environment and organisms. High hopes are placed on microscopies combined with neural networks for the quantification and characterization of nanoplastics in complex systems. This article describes the degradation pathways of plastics and the formation of nanoplastics in aquatic environments, and possible methods for separation and characterization of nanoplastics in relation to recent publications.
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