Mechanistic investigation of copper sorption onto γ-Al2O3 using the relaxation technique

Ternary [Al2O3–electrolyte–Cu2+] species: EPR spectroscopy and surface complexation modeling

“…Thus, taking into account the EPR data and the analytical speciation, we suggest that in the system [cAl 2 O 3 À Cu 2+ ] the copper ions form inner-sphere complexes with one surface O-atom, plus 3 O-atoms from coordinating H 2 O molecules. This is in agreement with the findings of Chang et al [12] for pH < 6.1. On the other hand, Motschi [5] found that-at pH 10-copper coordinates to two surface O-atoms of d-Al 2 O 3 .…”

“…As shown, at pH 6.5 all EPR spectra are characterized by the same spin-Hamiltonian parameters. This is the case for our data as well as in the experiments of Chang et al [12]. On the other hand at pH ) pH PZC where the species "SO À are formed at high concentrations, therefore closer to each other, Cu 2+ may coordinate to two "SO À group.…”

“…There are three general conclusions from these previous studies [5,7,[9][10][11][12][13][14][15][16][17]: (1) Most researchers concluded that Cu 2+ forms inner-sphere complexes with oxide surfaces. (2) At sufficiently low concentrations, Cu 2+ forms mononuclear complexes, with monodentate or bidentate coordination to the surface.…”

“…Significant research effort has been devoted to study the interactions of Cu 2+ with aluminum oxide surfaces, aiming to develop predictive models of Cu 2+ concentration and speciation in natural waters [5,7,[9][10][11][12][13][14][15][16][17]. There are three general conclusions from these previous studies [5,7,[9][10][11][12][13][14][15][16][17]: (1) Most researchers concluded that Cu 2+ forms inner-sphere complexes with oxide surfaces.…”

Effect of fulvic acid on the sorption of Cu and Pb onto γ-Al2O3

“…Hohl and Stumm [14] described the Pb=g-Al 2 O 3 system as the exchange of surface proton with Pb as well as a subsequent formation of SOPb þ surface complex. The intrinsic coordination constant ðlog K int Pb Þ was calculated as À2:2: Chang et al [27] illustrated that the reactions of the Cu=g-Al 2 O 3 system were the same as the Pb=g-Al 2 O 3 system and the intrinsic coordination constant ðlog K int Cu Þ was determined as 0.09. The reactions and intrinsic conditional equilibrium constants of the Cu=g-Al 2 O 3 and Pb=g-Al 2 O 3 systems are presented as follows:…”