Iron doped zircon – phase composition and environmental aspects

W artykule zawarto wyniki badań składu chemicznego i fazowego pigmentu cyrkonowo-żelazowego otrzymanego z zastosowaniem różnych surowców żelazowych i dodatków mineralizujących. Do badań zastosowano dyfrakcję rentgenowską (XRD), fluorescencyjną spektrometrię rentgenowską (XRF-WD) oraz skaningową mikroskopię elektronową wraz z analizą składu pierwiastkowego w mikroobszarach (SEM-EDS). Stwierdzono występowanie faz krystalicznych (neighborytu, gryceitu i egirynu litowego), które dotychczas nie były opisywane dla omawianych pigmentów cyrkonowo-żelazowych. W dyskusji odniesiono się również do znaczenia powstających faz dla efektów środowiskowych mających miejsce podczas wytwarzania pigmentów cyrkonowych.The chemical and phase composition of irondoped ZrSiO4 ceramic pigments synthesized from different iron raw materials and mineralizing agents were studied. The results were obtained using X-rays powder diffaction, X-rays fluorescence spectroscopy and scanning electron microscopy techniques. It was revealed for the first time for this pigment that fluorine forms its own stable phases (neighborite and gryceite) accompanied by lithium aegirine. The environmental meaning of the presence of these phases in ceramic pigment was discussed

Dawsonite as an indicator of multistage deformation and fluid pathways within fault zones: Insights from the Fore-Dukla Thrust Sheet, Outer Carpathians, Poland

The structural pattern developed within metre to microscopic scale thrust and strike-slip fault zones exposed in the Palaeogene flysch rocks of the Fore-Dukla Thrust Sheet in the south-eastern part of the Silesian Nappe, Outer Carpathians, Poland, reveals evidence for upper crustal deformation and fluid flow. Syntectonic dawsonite [NaAlCO3(OH)2] indicates the following series of deformational events within the fault zones: i) detachment and buckle folding resulting from movement along thrust faults; ii) faulting as a compensation of the shortening, resulting in the fault propagation folding, breakthrough thrust faulting and imbrications; and iii) strike-slip faulting. The microstructural pattern coupled with the growth of a related sequence of carbonate minerals within the fault zones, followed by present-day dawsonite precipitation and tufa formation, indicate a continuing influence of fluids within the Silesian Nappe up to and including modern time. Structural observations at metre to microscopic scales coupled with EDS mapping of rocks indicate that dawsonite is a unique tool for the reconstruction of subsequent deformation in the Fore-Dukla Thrust Sheet

Synthesis of SiC/Ag/Cellulose Nanocomposite and Its Antibacterial Activity by Reactive Oxygen Species Generation

We describe the synthesis of nanocomposites, based on nanofibers of silicon carbide, silver nanoparticles, and cellulose. Silver nanoparticle synthesis was achieved with chemical reduction using hydrazine by adding two different surfactants to obtain a nanocomposite with silver nanoparticles of different diameters. Determination of antibacterial activity was based on respiration tests. Enzymatic analysis indicates oxidative stress, and viability testing was conducted using an epifluorescence microscope. Strong bactericidal activity of nanocomposites was found against bacteria Escherichia coli and Bacillus cereus, which were used in the study as typical Gram-negative and Gram-positive bacteria, respectively. It is assumed that reactive oxygen species generation was responsible for the observed antibacterial effect of the investigated materials. Due to the properties of silicon carbide nanofiber, the obtained nanocomposite may have potential use in technology related to water and air purification. Cellulose addition prevented silver nanoparticle release and probably enhanced bacterial adsorption onto aggregates of the nanocomposite material

Technogenic soils (Technosols) developed from fly ash and bottom ash from thermal power stations combusting bituminous coal and lignite : part II : mineral transformations and soil evolution

Fly ash and bottom ash from thermal power stations are industrial wastes which are susceptible to weathering in the environment. First manifestations of transformations occur immediately after deposition of ashes in a disposal site and they continue in technogenic soils (Technosols) developing from the ashes on surfaces of such sites. Technosols developed from bituminous coal and lignite ashes in Poland were studied in order (a) to identify the most important mineral transformations during the first several decades of soil development, and (b) to discuss the evolution of these soils. Mineral transformations can serve as good indicators of pedogenesis in the studied Technosols. Quantitative X-ray diffraction analyses, Fourier transform infrared spectroscopy, optical microscopy, and scanning electron microscope-energy dispersive spectroscopy studies showed that the mineral transformations proceeded more dynamically in Technosols developed from lignite ashes, whereas they were less expressed in soils formed from bituminous coal ashes. Technosols developed from bituminous coal ashes contained mineral phases inherited from ashes (aluminosilicate glass, mullite, quartz, magnetite, hematite, and traces of maghemite and barite) as predominating constituents. Small contents of pedogenic calcite, iron oxyhydroxides, and most likely short-range order Si- and Al-containing phases originated within ~ 60 years of pedogenesis. Technosols developed from lignite ashes contained aluminosilicate glass, quartz, hematite inherited from fly ash, as well as a variety of secondary minerals (vaterite, calcite, bassanite, gypsum, ettringite, hydrotalcite, and brucite) which were formed as an effect of rapid mineral transformations after ash deposition. After about 40 years, pedogenesis (accelerated by reclamation and a few years of intense cultivation) led to the formation of a new mineral assemblage with the predomination of calcite, gypsum, and hydrotalcite. A concept of evolution of the studied Technosols comprising four stages of evolution was proposed: I - formation of ash during combustion of fuel (coal or lignite) in a thermal power station, II - transport and deposition of ash in a disposal site accompanied by the first weathering alterations, III - early pedogenesis, and IV - further (predicted) evolution

Air Purification Performance of Photocatalytic Concrete Paving Blocks after Seven Years of Service

This paper presents the results of laboratory tests on photocatalytic pavement blocks from a bicycle lane in Poland after seven years of service. Air purification performance was tested on dusty and clean samples using different light sources and setups, with non-laminar gas circulation. Secondary Electrons Secondary Ions (SESI) and InLens detectors combined with SEM−EDS and X-ray analyses were applied to confirm the presence of TiO2 in the studied blocks. The obtained results show that TiO2 was present in the form of agglomerates with a diameter of 0.25−5 µm and was bonded to the cement matrix components. The tested samples still maintained nitric oxide (NO) removal capability with a NO reduction rate of 4−45%, depending on light source and surface cleanliness