“…The adsorption of Co as a function of pH has been studied using macroscopic laboratory methods on simple solids including hydrous ferric oxide (Kurbatov et al 1951a,b;Kurbatov and Wood, 1952;Duval and Kurbatov, 1952;Benjamin and Bloom, 1981;Benjamin, 1983;Dzombak and Morel, 1990;Ainsworth et al, 1994), kaolinite (Angove et al, 1998;Benyahya and Garnier, 1999;Chen and Hayes, 1999;Ikhsan et al, 1999) and quartz or silica (James and Healy, 1972;O'Day et al 1996;Chen and Hayes, 1999;Berka and Banyai, 2001;Chen et al, 2006). X-ray absorption spectroscopy has been used to characterize the nature of Co surface complexes on quartz (Charlet and Manceau, 1994;O'Day et al, 1996;Manceau et al, 1999;Chen et al, 2006) and several clay minerals (Chisholm-Brause et al, 1990;O'Day et al, 1994;Charlet and Manceau, 1994;Chen and Hayes, 1999;Schlegel et al, 1999a,b;Thompson et al, 1999Thompson et al, , 2000.…”