Sorption of Me3+ on K-feldspar
Sorption edges of Eu, La, Lu, Nd, and Y on K-feldspar are plotted in Fig. 1. Constant, low sorption is detected for pH<5. The amount of sorption in this pH range depends on ionic strength, indicating outer sphere sorption. A steep increase in sorption was observed between pH 6 and 7, leading to complete sorption at pH ≥ 7.5. At higher pH, sorption remains constant at ~100 %. For high metal concentrations (100 µM), surface precipitation cannot be excluded at high pH.
Fig. 1: Sorption edge of Me3+ onto K-feldspar. For detailed information please see Neumann et al. (2020).
Sorption of Eu3+ on mica, K-feldspar, and quartz
Further information on Eu3+ sorption on ubiquitously present minerals can be found in Britz (2018). The thesis illustrates the stepwise approach to reactive transport simulations of Eu under artificial and close to nature geochemical boundary conditions: In a first step, the measurement of surface charge development and the modeling of the acid base behaviour (mechanistic surface charge models) is addressed. The results of this preliminary step are mandatory to describe Eu surface complexation based on sorption experiments coupled with mechanistic surface complexation models (SCMs) in a second step. The third part of this approach combines surface charge models and SCMs to develop reactive transport models (RTMs) which are used to predict Eu reactive transport processes. The main objective was the development of RTMs for muscovite, orthoclase, quartz, and a synthetic sediment to predict the reactive transport of the trivalent lanthanide under different geochemical conditions.
Neumann, J., Brinkmann, H., Britz, S., Lützenkirchen, J., Bok, F., Stockmann, M., Brendler, V., Stumpf, T., Schmidt, M., 2020: A comprehensive study of the sorption mechanism and thermodynamics of f-element sorption onto K-feldspar, J. Colloid Interface Sci. 2020. https://doi.org/10.1016/j.jcis.2020.11.041.
Britz, S.: Europium sorption experiments with muscovite, orthoclase, and quartz: Modeling of surface complexation and reactive transport, PhD thesis, DOI 10.24355/dbbs.084-201806051207-0, GRS Braunschweig, Theodor-Heuss-Sr. 4, Abt. 401, 38122 Braunschweig (2018).
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