Otěrové částice z frikčních kompozitů brzdových obložení automobilů a jejich vliv na biosystémy.

Abstract

The road traffic represents a major source of gaseous and particulate emissions, which could negatively affect the environment. This dissertation thesis focuses on studying the automotive brake wear particles as one of the traffic pollution components and due to minimization of exhaust emissions, this source is gaining more attention of industry and researchers as well. The main goal of the dissertation thesis is a complex characterization of the brake wear debris, which were generated by „full-scale“ brake dynamometer under laboratory conditions. Three samples of the suspended fraction (AP1-3) and three samples of the sedimented fraction (NAP1-3) were studied by the scanning and transmission electron microscopy, X-ray fluorescence analysis and X-ray powder diffraction, FTIR spectroscopy and Raman microspectroscopy and particle size distribution was evaluated. The studied particles mainly consist of iron and its oxides and of carbon. The median size of AP particles is around 11-16 µm, NAP is around 72-81 µm. A significant amount of nanoscale particles was detected in both studied fractions. The electron paramagnetic resonance, aqueous extract analysis and determination of present organic substances by gass chromatography was performed on the selected samples. The second goal of the dissertation is studying the brake wear debris impact on the biosystems in vitro. The methods of lipid peroxidation and protein carbonylation determination were used for the assessment of the samples capability to cause oxidative stress. Also the acute aquatic toxicity for freshwater green algae Raphidocelis subcapitata was studied. Effect of brake wear debris suspension and extract on the germination, root elongation and the early growth of higher plants of Hordeum vulgare and Sinapis alba was also studied. The tests results show the potential of negative impact of break wear particles on the environment and living organisms.