Browsing by Subject "dissolution"

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Eksperymentalny model przemian cerusytu $PbCO_{3}$ w hydroksylmimetyt $Pb_{5}(AsO_{4})_{3}OH$
(Data obrony: 2012-07-16) Kosobudzka, Anna
Wydział Geologii, Geofizyki i Ochrony Środowiska
Bioavailability of $Pb$ and $A$s depends strongly on thermodynamic stability of crystalline species controlling their concentration in solutions. However, the mechanisms of transformation of more soluble cerrusite $PbCO_{3}$ into less soluble lead apatites are not well understood. In this study, the concentration of aqueous $Pb^{2+}$ and formation of secondary phases were monitored during dissolution of cerrusite $PbCO_{3}$ in the presence of $AsO_{4}{ ^{3-}}$ at various pH. XRD and SEM/EDS analyses indicate that hydroksylmimetite $Pb_{5}(AsO_{4})_{3}OH$ is the only reaction product at alkaline pH. In acidic solutions the main product of cerrusite reaction with arsenate ions is more soluble and less stable shultenite $PbHAsO_{4}$. Control reaction with lead ions from $Pb(NO_{3})_{2}$ allows to determine a $CO_{3}{^{2-}}$ substitution in the structure of lead apatites precipitating in the presence of cerrusite.
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Stabilność hydrocynkitu w roztworach wodnych zawierających jony fosforanowe
(Data obrony: 2012-12-20) Zemanek, Adriana
Wydział Geologii, Geofizyki i Ochrony Środowiska
The solubility of hydrozincite in aqueous solutions containing phosphate ions was determined by examining the process and products of dissolution reaction of the mineral in the presence of phosphate ions. In order to determine the effect of pH on the reaction, experiment was carried out in the pH range 2–7. The results of analysis show that the concentration of soluble Zn depended upon the pH. The dissolution rates of hydrozincite decreased with increasing pH. The characteristics of the formed precipitate were investigated by powder X-ray diffraction analysis and FTIR analysis. The product of the reaction is hydrated zinc phosphate - hopeite. The data show that the formation of hopeite may influence both the availability of zinc in soils and the zinc levels in natural water systems.
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Wpływ kwasu glukonowego na rozpuszczalność piromorfitu
(Data obrony: 2013-09-13) Borowicz, Paweł
Wydział Geologii, Geofizyki i Ochrony Środowiska
Phosphate-induced lead immobilization method is based on the fact that newly formed mineral, pyromorphite, is a highly insoluble phase. However, there is a number of factors capable of decreasing stability of pyromorphite. Among them are low-molecular-weight organic acids (LMWOA) secreted to the soil by numerous species of microorganisms and plants. Presented studies investigate the relation between pyromorphite and gluconic acid (GA), one of the most common LMWOA in the soil. The conducted experiments includes dissolution of pyromorphite in the presence of GA, having regard to the pH of the solution or concentration of GA, and formation of pyromorphite in the presence of GA (homogeneous and heterogeneous transformations). The studies indicate that GA increase the dissolution of pyromorphite through decreasing pH of the solution, Pb-organic complexation and increasing the ionic strength of the solution. GA inhibits growth of pyromorphite crystals through formation of complexes with crystal seeds and reducing activity coefficient of lead cations.
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Wpływ metody roztwarzania próbek osadów na jakość zawartości metali
(Data obrony: 2012-09-28) Olearczyk, Monika
Wydział Geologii, Geofizyki i Ochrony Środowiska
In this study were carried out laboratory tests to find the best dissolution method for chemical elements. The research was conducted on certified reference materials (IAEA 405, 2704 River Sediment, LKSD 4, SRM 1646). CRM were dissolution in mineralizator and microwave oven in acid like H2SO4, HNO3,HCl and acid mixtures like Aqua regi. Determination of metals such as Zn, Pb, Mn, Cr and Fe was done by Atomic Absorption Spectroscopy.