|
|
Leachability of Ba and Cr from alkali-activated matrices
Cába, Vladislav ; Hajzler, Jan (referee) ; Koplík, Jan (advisor)
The aim of this work is to determine the usability of alkaline activated matrices made from ashes to inhibition of barium and chrome. Ashes – fly ashes and ashes from fluidized bed combustion – were compared with cement used for inhibition. By using inductively coupled plasma atomic emmission spectrometer were determined concentrations of barium and chrome in leachates based on norm ČSN EN – 12457-4. In addition, images were taken on the scanning electron microscope and crystallographic spectra from X-ray crystalography were obtained to determine structure. The results show that ashes from fluidized bed combustion are suitable for inhibition of both barium and chrome, whereas fly ashes can not sustain these elements with such success.
|
|
|
Environmental Aspects of Pyrotechnic Mixtures.
Mešková, Michala ; Bednařík, Karel (referee) ; Friedl, Zdeněk (advisor)
The submitted bachelor thesis deals with the study of pyrotechnic compositions and their influence on the health and environment. It explains the nature and ingredients used in pyrotechnic compositions. During burning these compositions release different compounds, toxic or non-toxic into the atmosphere in large quantities. In this work the issue of toxicity of selected alkali, alkaline earth metals and the other harmful metals was explored. The pyrotechnic compositions containing Ba, As, Pb and Cd were investigated in more detail. When burning the pyrotechnic compositions release noxious substances into the air first. Then these substances reach due to wet or dry transport mechanism the other components of the environment and mix with them. These compounds have diverse negative effects both on humans and the environment and other animals.
|
|
|
The influence of barium and its compounds on the formation and properties of Portland clinker
Zezulová, Anežka ; Rovnaníková, Pavla (referee) ; Palou, Martin (referee) ; Ptáček, Petr (advisor)
The work deals with the study of barium cement. Barium cements are used to prepare concrete that protects against ionizing radiation. Barium can be also present in a conventional Portland cement clinker as an impurity from alternative fuels or raw materials, which are increasingly used for clinker production, and thus change the structure and properties of the product. Various methods of preparation of this cement were studied in this work. Barium cements were prepared from raw meals of different composition, but always with the same procedure and burning temperature. Using suitable analytical methods, the work describes the influence of individual admixtures of raw meal on the phase composition of the resulting clinker. Furthermore, the work deals with monitoring the form and location of barium in the prepared clinker. Several experiments are focused on the study of hydration of prepared barium clinkers, the phase transformation is monitored by XRD and supplemented by analyses of hydration products. In this way, it was possible to obtain the data needed to describe the preparation, burning, and hydration of barium cements with different compositions. The work also deals in detail with the real use of barium cements. The ability of pastes and mortars from prepared barium cements to shield various types of ionizing radiation was tested and described experimentally. The results are presented in comparison with reference samples, which were prepared from commonly used Portland cement.
|
|
|
The influence of barium and its compounds on the formation and properties of Portland clinker
Zezulová, Anežka ; Rovnaníková, Pavla (referee) ; Palou, Martin (referee) ; Ptáček, Petr (advisor)
The work deals with the study of barium cement. Barium cements are used to prepare concrete that protects against ionizing radiation. Barium can be also present in a conventional Portland cement clinker as an impurity from alternative fuels or raw materials, which are increasingly used for clinker production, and thus change the structure and properties of the product. Various methods of preparation of this cement were studied in this work. Barium cements were prepared from raw meals of different composition, but always with the same procedure and burning temperature. Using suitable analytical methods, the work describes the influence of individual admixtures of raw meal on the phase composition of the resulting clinker. Furthermore, the work deals with monitoring the form and location of barium in the prepared clinker. Several experiments are focused on the study of hydration of prepared barium clinkers, the phase transformation is monitored by XRD and supplemented by analyses of hydration products. In this way, it was possible to obtain the data needed to describe the preparation, burning, and hydration of barium cements with different compositions. The work also deals in detail with the real use of barium cements. The ability of pastes and mortars from prepared barium cements to shield various types of ionizing radiation was tested and described experimentally. The results are presented in comparison with reference samples, which were prepared from commonly used Portland cement.
|
|
|
Leachability of Ba and Cr from alkali-activated matrices
Cába, Vladislav ; Hajzler, Jan (referee) ; Koplík, Jan (advisor)
The aim of this work is to determine the usability of alkaline activated matrices made from ashes to inhibition of barium and chrome. Ashes – fly ashes and ashes from fluidized bed combustion – were compared with cement used for inhibition. By using inductively coupled plasma atomic emmission spectrometer were determined concentrations of barium and chrome in leachates based on norm ČSN EN – 12457-4. In addition, images were taken on the scanning electron microscope and crystallographic spectra from X-ray crystalography were obtained to determine structure. The results show that ashes from fluidized bed combustion are suitable for inhibition of both barium and chrome, whereas fly ashes can not sustain these elements with such success.
|
|
|
Environmental Aspects of Pyrotechnic Mixtures.
Mešková, Michala ; Bednařík, Karel (referee) ; Friedl, Zdeněk (advisor)
The submitted bachelor thesis deals with the study of pyrotechnic compositions and their influence on the health and environment. It explains the nature and ingredients used in pyrotechnic compositions. During burning these compositions release different compounds, toxic or non-toxic into the atmosphere in large quantities. In this work the issue of toxicity of selected alkali, alkaline earth metals and the other harmful metals was explored. The pyrotechnic compositions containing Ba, As, Pb and Cd were investigated in more detail. When burning the pyrotechnic compositions release noxious substances into the air first. Then these substances reach due to wet or dry transport mechanism the other components of the environment and mix with them. These compounds have diverse negative effects both on humans and the environment and other animals.
|
guest ::
