Silicate Sorption on Ankerite from a Standard Silicate Solution
This work represents the potential impact of geological deposition conditions on the durability of glass used for radioactive waste disposal. The durability of highly radioactive glass could be influenced by iron mineral compositions or other near field parameters inside the final disposal repository. In this paper, silicate sorption by natural ankerite is experimentally studied. Preliminary study using the graphite furnace atomic absorption method to measure the change in concentrations of silicon in standard solution in the presence of natural ankerite was performed. All standard solutions were diluted from a saturated silicate stock solution. Natural ankerite mineral samples which were collected from Rudabánya, Hungary, showed strong sorption of (H4SiO4) on their interface. Batch experiments containing specific masses of natural ankerite and silicate solution were carried out in order to illustrate a better understanding of silicate reduction in solution due to the sorption mechanism of ankerite, evidence that ankerite has the ability to uptake silicate was seen. The desorption of adsorbed silicate was tested and it was noticed that only very small amounts of silicate returned to the solution showed tiny reversed concentrations of silicate which may an indication of chemisorption.