Determination of pore water composition during long term interaction of bentonite substrates with water media: Comparative study
|Článek v odborném periodiku
|Časopis / Zdroj
|Applied Clay Science
|Fakulta / Pracoviště MU
|Bentonite; Pore water extraction; Mock-Up-Cz experiment; Centrifugation; Leaching
|This paper reports validation results of two frequently used extraction methods centrifugation and leaching for determination of bentonite porewater chemistry. Three types of bentonite materials were used in our study. All the bentonite samples were placed into pressure vessels and interacted with natural water during a one-year experiment. Free water, obtained during these interactions, was used as a comparative pore water composition for both of the extraction methods. Concentrations of Mg2+, Ca2+, K+ and Na+ in water were determined. Centrifugation could be generally considered as a more suitable method because of the smaller differences between free water composition and concentrations obtained from extracted pore water compared to the leaching method. However, actual differences depend on the type of bentonite and on the composition of the water media. In some cases, the leaching method yields better results. Leaching usually leads to higher concentrations of alkali metals and lower concentrations of alkaline earth metals. This indicates that bentonite substrates are sensitive to the change of external conditions and quickly interact with the water media.