Outer-sphere adsorption

Outer-sphere adsorption of Pb(ll)EDTA on goethite. Geochim. Cosmochim. Acta 63(19/20) 2957-2969 Bargar, J.R. Reitmeyer, R. Davis, J.A. (1999) Spectroscopic confirmation of uranium(Vl)-carbonato adsorption complexes on hematite. Environ. Sci. Techn. 33 2481-2483 Bargar, J.R. Reitmeyer, R. Lenhart, J.J. Davis, J.A. (2000) Characterization of U(Vl)-car-bonato ternary complexes on hematite EX-AFS and electrophoretic mobility measurements. Geochim. Cosmochim. Acta 64 ... 

Johnson, S.B. et al.. Adsorption of organic matter at mineral/water interfaces. 2. Outer-sphere adsorption of maleate and implications for dissolution processes, Langmuir, 20, 4996, 2004. 

Bargar, J.R., Persson, P, and Brown, G.E., Outer-sphere adsorption of PbfB) EDTA on goethite, Geochim. Cosmochim. Acta, 63, 2957, 1999. 

Bargar JR, Persson P, Brown GE Jr (1999b) Outer-sphere adsorption of Pb(II)EDTA on goethite. Geochim Cosmochim Acta 63 2957-2969... 

To explore this question, the adsorption of glycine on AlOOH was recently investigated at the interface with water [78, 97]. This study confirmed the occurrence of an inner sphere Al-O-C-0 bond that was predicted from calculations at the interface with vacuum, and from numerous experimental studies of carboxylic acid adsorption on alumina polymorphs (see Ref. [78] and references therein). It was found that inner sphere adsorption (shown in Fig. 5.14, right), with -161.6 and -113.6 kJ moF for the anionic and zwittetionic species, respectively is significantly more stable as compared to outer sphere adsorption (-20.5 kJ mol (Fig. 5.14, left)). Beyond the result itself, it is important to note that complex events can now he handled with ab initio methods because they are able to model aU types of forces in reasonable agreement with experiment. 

FIGURE 5.14 Supercells used for the study of glycine adsorption on AlOOH boehmite at the interface with water in the outer-sphere adsorption mode G ft), and inner sphere adsorption mode (right). With permission ftom Motta et al. [78]. 

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