Browsing by Subject "immobilization"

Now showing 1 - 6 of 6

Access status: Open Access ,
Aqueous cadmium removal by hydroxylapatite and fluoroapatite
(Wydawnictwa AGH, 2012) Matusik, Jakub; Bajda, Tomasz; Manecki, Maciej
Reducing the bioavailability of toxic heavy metals in groundwaters and urban soils by phosphate addition is an effective technique described in the literature. It is based on the reaction between metal ions and phosphates and results in the precipitation of metal substituted phosphate phases. The formed phosphates are highly insoluble and thermodynamically stable over almost entire pH and Eh range. In the presented study the efficiency and mechanism of cadmium uptake by synthetic hydroxylapatite and natural fluoroapatite was examined within the pH range of 3-7 for different reaction times (2—1440 hours). The solids after reactions were characterized by XRD and SEM-EDS. Percentage reduction of cadmium concentration in the experiments with fluoroapatite and hydroxylapatite, regardless of pH, did not exceed 17% and 25%, respectively. Cadmium uptake from the solution mainly resulted from the formation of cadmium phosphates and/or Ca-Cd phosphate solid solutions on the apatites surface. The release rate of phosphate ions by hydroxylapatite was relatively high. This promoted crystallization of a large number of small crystals. In turn dissolution of fluoroapatite was slower and thus the formation of large crystals was observed. There was no clear evidence for cadmium-calcium ion-exchange mechanism.
Access status: Restricted ,
Dobór optymalnej metody immobilizacji metali w osadach
(Data obrony: 2016-07-14) Wojciechowska, Paulina
Wydział Geologii, Geofizyki i Ochrony Środowiska
Proces wymywania metali ciężkich z osadów jest ściśle uzależniony od pH środowiska wodnego. Dobre właściwości buforowe osadu są cechą pożądaną, ponieważ wraz ze wzrostem zakwaszenia środowiska wodnego wzrasta stężenie uwalnianych pierwiastków. W niniejszej pracy podjęto próbę immobilizacji Cd, Zn oraz Pb w zanieczyszczonych osadach rzecznych z wykorzystaniem soli fosforanowych oraz minerałów naturalnych. Za najlepszy dodatek pozwalający na immobilizację Cd uznano diwodorofosforan sodu $(NaH_{2}PO_{4}; \; 91\%)$. Fosforan wapnia $(Ca(H_{2}PO_{4})_{2})$ okazał się najefektywniej sprzyjać immobilizacji Pb (100%), natomiast w przypadku Zn był to kaolinit (69%).
Access status: Restricted ,
Eksperymentalny model przemian cerusytu $PbCO_{3}$ w hydroksylpiromorfit $Pb_{5}(PO_{4})_{3}OH$
(Data obrony: 2012-07-16) Stożek, Katarzyna
Wydział Geologii, Geofizyki i Ochrony Środowiska
The objective of this study was characterization of the mechanism of transformation of cerrusite $PbCO_{3}$ into secondary phases in presence of phosphates $PO_{4}{^{3-}}$. The concentration of aqueous $Pb^{2+}$ and formation of secondary phases were monitored during dissolution of cerrusite $PbCO_{3}$ in the presence of $PO_{4}{^{3-}}$ at various pH. XRD and SEM/EDS analyses indicate that in acidic solutions the main product of cerrusite reaction with arsenate ions is phosphoshultenite $PbHPO_{4}$. Hydroksylpyromorphite $Pb_{5}(PO_{4})_{3}OH$ is the only reaction product at alkaline pH. Phospho-shultenite undergoes recrystalization into hydroxylpyromorphite after pH is raised to 9. Simulation of the reaction with PHREEQC model was unsuccessful probably due to poor thermodynamic data and lack of equilibrium in experimental system.
Access status: Restricted ,
Immobilizacja metali ciężkich z przemysłu cynkowo-ołowiowego
(Data obrony: 2013-07-11) Korczak, Joanna
Wydział Geologii, Geofizyki i Ochrony Środowiska
In situ immobilization of heavy metals in wastes from zinc-lead industry using phosphoric acid, ammonium phosphate, and portland cement is a prospective method to immobilize Pb, Cd, Zn. Based on the analyzes, TCLP test and leaching test was found the highest percentage reduction in the concentration of Pb, Cd, and Zn in with both the flotation tailing and steel slag has a phosphoric acid. Based on TCLP test rated effectiveness of immobilization Pb, Cd, Zn for the flotation waste is 100, 70, 60% and for steel slag 60, 30, 80% respectively. Extras such as fertilizer glassy or bog iron ore showed poor properties immobilization of heavy metals analyzed. As a result of SEM analysis showed that as a reaction product of phosphoric acid with waste phosphate, steel slag produced, primarily calcium phosphate. There are in the form of needle-like form of crystallizing the different materials present in the waste. EDS analysis showed that substitution metals present in the reaction medium such as Pb, Cd, Zn in structure calcium phosphate are possible. Isomorphic substitution in the structure of calcium phosphate is one of the possible mechanisms that occur in the test samples of flotation tailing and steel slag.
Access status: Open Access ,
The effect of Ca-Pb and P-As substitutions on the solubulity of hydroxylapatites
(Wydawnictwa AGH, 2016) Młynarska, Maria; Puzio, Bartosz; Kwaśniak-Kominek, Monika; Manecki, Maciej
Hydroxylapatites are important biomaterials. Substitutions of Pb for Ca and As for P in hydroxylapatites are recently intensively studied due to their significance in the environmental immobilization of Pb and As (Lee et al. 2009, Chlebowska et al. 2015, Motyka et al. 2015).
Access status: Restricted ,
Zastosowanie cementu portlandzkiego w rekultywacji gleb zanieczyszczonych metalami ciężkimi
(Data obrony: 2013-09-25) Cieślik, Gabriela
Wydział Geologii, Geofizyki i Ochrony Środowiska
Soil contamination with heavy metals such as lead, zinc and cadmium, is a very serious problem in the environment. One of the methods of soil remediation, such a method of stabilization/solidification (S/S) with the use of Portland cement. The study involved two samples of smelter-contaminated soil and sediment sample from the sludge landfill, in the area of the smelting complex of Bukowno. Based on the results of toxicity and bioavailability tests concluded that even 1% of Portland cement addition to samples of the soil and sludge landfill, giving the results of reducing the leachability and bioavailability of heavy metals, while 10% addition of cement is the most effective. Analysis of the influence pH has shown that 10% of the cement additive is adjusted to increase the pH of the soil to a level above 7 at which the metals are the least mobile. X-ray analysis, and SEM-EDS showed that the reaction product of samples of sludge from Portland cement hydration, or portlandite, formed hardly soluble carbonates of heavy metals. This reaction determines the process of immobilization of metals in soils.