Surface complexation modeling of Co(II) adsorption on mixtures of hydrous ferric oxide, quartz and kaolinite

Insights into tetracycline adsorption onto kaolinite and montmorillonite: experiments and modeling

“…The equilibrium constants K (≡SOH2+) , K (≡SO−) , K (≡SOH2+ NO3−) , K (≡SO− Na+) , and K (≡X− Na+) and layer capacitance C 1 and C 2 for kaolinite and montmorillonite could be estimated through the fitting for titration data at different ionic strengths with the FITEQL program (Goldberg 2005;Landry et al 2009). Besides, the site density (N t ) is a critical parameter for TLM.…”

“…The capacitance of inner and outer Helmholtz layer for kaolinite and montmorillonite is 1.5 and 5 F m −2 a Constants from reference (Figueroa et al 2004) b logK 0 was averaged from values in the three ionic strengths which were adjusted to zero ionic strength using the Davies equation (Gu et al 2010) c Constants from reference (Goldberg 2005) d Constants from reference (Landry et al 2009) e Optimized from FITEQL in this work Fig. 3 Modeled surface speciation diagrams of TC adsorption onto kaolinite (KT, 1 g L −1 ) and montmorillonite (MT, 0.2 g L −1 ) at three ionic strengths, 25°C.…”

Adsorption of Cr(VI) on γ-alumina in the presence and absence of CO2: Comparison of three surface complexation models

“…This may be in part because the TLM does not converge when too many parameters are optimized simultaneously, as for example, observed by Lü tzenkirchen (1998). The DLM, which requires the fewest fit parameters, might be further improved by using ionicstrength dependent stability constants, as has been suggested in some prior studies (e.g., Sverjensky and Sahai, 1996;Landry et al, 2009;Reich et al, 2010), although the edges would still be too steep. It is also important to note that the CCM, DLM and TLM are very often used to fit data derived over very restricted ranges of ionic strength and pCO 2 .…”

Mathematical Formulation Requirements and Specifications for the Process Models

“…In the CA approach, it is assumed that a mineral assemblage is composed of a mixture of one or more reference phases, whose surface chemical reactions are known from independent studies of each phase (e.g. Arnold et al, 2001;Davis et al, 2004;Landry et al, 2009). Based on a measurement of the relative amounts or surface areas of each mineral present in the soil or sediment, sorption by the mixture of phases can be predicted by an equilibrium calculation, without any fitting of experimental data for the mixture.…”