Considerable amount of waste in the form of polyethylene terephthalate (PET) bottles could be utilized in the form of dispersed microreinforcement in concrete. PET fibres, however, have poor wettability and adhesion to cement paste, which can be modified by alkaline hydrolysis with sodium hydroxide at elevated temperature. The alkaline treatment was used to increase fibre surface, which was followed by changes in the structure of the interfacial transition zone (ITZ) and interfacial bond between fibre and cementitious matrix. Raman microspectroscopy mapping was employed to study microstructural changes of ITZ within the distance 0 - 250 μm from a PET fibre. The band at 357 cm-1 corresponding to the Ca-O bond vibration in portlandite was used to determine its distribution. For determination of the relative abundance of ettringite, the SO42- stretching vibration at 987 cm-1 was used. The most intensive bands of portlandite and ettringite were found within the distance 0 - 50 μm from an unmodified PET fibre. Besides the elevated concentration of these minerals, abundant pores occur in this region. In the case of alkaline modified PET fibres the ITZ zone was not found., Vladimír Machovič, Ladislav Lapčák, Lenka Borecká, Miloslav Lhotka, Jana Andertová, Lubomír Kopecký and Linda Mišková., and Obsahuje bibliografii
A combined sorbent was prepared by impregnation of lignite mined in the South Moravian Coalfield, Czech Republic, with chitosan. Sorption performance of the combined sorbent and the untreated lignite was tested for Co(II), Cu(II), and Cd(II) in equilibrium sorption experiments with respect to pH and metal concentration. The amount of metal retained by the sorbent was determined by instrumental neutron activation analysis in the short time irradiation mode with epithermal neutrons. For pH~5, sorption isotherms were determined and fitted using the Langmuir and Freundlich models. The results have been compared with those obtained previously for similar combined sorbent based on naturally oxidized coal mined in the Sokolov Basin, Czech Republic. It has been shown that the effect of chitosan on sorption efficiency of the chitosan-doped coal sorbents strongly depends on solution pH, and type of coal and metal., Martina Havelcová, Jiří Mizera, Vladimír Machovič, Lenka Borecká, Oldřich Přibyl and Ivana Krausová., and Obsahuje bibliografii