Reaction rates of heavy metal ions at goethite: relaxation experiments and modeling

Eigen Kinetics in Surface Complexation of Aqueous Metal Ions

“…On the whole, the surface has an appreciable positive charge density, giving rise to a local potential of approximately +110 mV at the position of the Cu 2+ ion in its outer-sphere ion pair with the surface site . The goethite dispersions studied had an area-to-volume ratio, A / V , of 5 × 10 5 m −1 , and the characteristic adsorption time τ ad was found to be in the range of 20 to 40 ms, with solid evidence that diffusion of Cu 2+ in solution is fast on this time scale . Since the experimental data were obtained for a large excess of sites over Cu(II), the surface complexation reaction rate R a s (cf.…”

Kinetic research on the sorption of aqueous lead by synthetic carbonate hydroxyapatite

“…Environmental mineralogy is a new, interdisciplinary subject that investigates not only how minerals cause environmental problems, but also how they resolve them. As far as the latter is concerned, such minerals as zeolite (Chlopecka and Adriano, 1997;Chang et al, 2004a, b;Pitcher et al, 2004;Ö ren and Kaya, 2006), goethite (Trivedi and Axe, 2001;Mustafa et al, 2004;Pohlmeier and Lustfeld, 2004;Lackovic et al, 2004), magnetite (Stipp et al, 2002;Chang et al, 2004a, b;Martı´nez et al, 2004), perlite (Alkan and Dogan, 2001;Dog˘an et al, 2004;Acemiog˘lu, 2005) and so forth, are used to resolve various environmental pollutions. Apatites have been the object of considerable attention (Miyake et al, 1990;Jeanjean et al, 1996;Chen et al, 1997a, b;Fuerstenau et al, 1997;Admassu and Breese, 1999;Manecki et al, 2000;Mavropoulos et al, 2002;Arnich et al, 2003;Mavropoulos et al, 2004;Go´mez del Rı´o et al, 2004;Peld et al, 2004;Lee et al, 2005;Raicevic et al, 2005;Knox et al, 2006) because of their peculiar crystal-chemistry characteristics, and it has been proposed that they can be used to remove heavy metal ions, including lead, from contaminated wastewaters (Mavropoulos et al, 2004).…”

Copper and zinc removal from aqueous solution by mixed mineral systems

“…This is based on the reasoning that where sorption involves both electrostatic and specific attraction, sorption of sorbing ions could exceed the number of net proton surface sites; otherwise, sorption could be less or near equal to the number of available reactive surface sites [16]. Speciation of the solutions with respect to complexes of Cu(OH) 2 and Zn(OH) 2 was found to be undersaturated at pH 6.5 and the range of Cu or Zn concentration used in this study.…”

“…For successful treatment of wastewater containing Cu and Zn ions, a full understanding of the reactivity and the transport of reaction partners to the reactive sites of mixed mineral particles is required for environmental fate and managerial decisions [1,2].The removal of Cu and Zn ions from wastewater is controlled by the mobility and ionic size of the sorbing ions, sorbate composition, sorbent solubility, sorbent particle size, sorbent surface charge, external surface area of the sorbent, solution dilution and H + /M 2+ , exchange stoichiometry [2,3].…”