Adsorption of Heavy Metals by Clay-Aluminum Hydroxide Complexes

Local coordination of Zn in hydroxy-interlayered minerals and implications for Zn retention in soils

“…From Znsorbed gibbsite spiked into quartz powder, about 60% of the total Zn were extracted in the first two steps of the SEP. In comparison with the data for Zn-HIS-6.9-pH5, this indicates that Zn sorbed to hydroxy-Al polymers in clays is more strongly retained than Zn sorbed to gibbsite, in agreement with previous work (Keizer and Bruggenwert, 1991). The SEP results thus suggest that Zn sorption to aluminium (hydr)oxides was not dominant in the studied soils.…”

“…1016/j.gca.2008.10.026 adsorption to pure montmorillonite at acidic pH is dominated by cation exchange (Lothenbach et al, 1997;Saha et al, 2001;Janssen et al, 2003b). Furthermore, hydroxyAl polymers bound to a clay surface have a higher affinity for metal sorption than pure Al hydroxides (Keizer and Bruggenwert, 1991). Recent studies on Zn sorption to hydroxy-interlayered minerals using extended X-ray absorption fine structure (EXAFS) spectroscopy confirmed the uptake of Ni and Zn into the vacant octahedral sites of gibbsitic hydroxy-Al interlayers in montmorillonite (Nachtegaal et al, 2005b;Schlegel and Manceau, 2007).…”

Reactions Controlling Heavy Metal Solubility in Soils

“…Heavy metals of appropriate charge and radius may be able to act as a proxy for Mg2+ in the interlayer. Evidence for this has been suggested by the strong selectivity of smectites interlayered with AI hydroxy polymers for Cu2+ and Zn2+ relative to Pb2+ and Cd 2 + (Keizer and Bruggenwert, 1986). The latter metals are too large to be accommodated in the octahedral coordination sites of hydrotalcite.…”

Adsorption of cadmium onto Al13-pillared acid-activated montmorillonite

“…Recently, adsorption of a variety of heavy metals onto pillared clays has been reported [12][13][14][15][16][17][18][19][20][21][22]. Cu adsorption was increased by the presence of hydroxyaluminum polymeric components on Wyoming montmorillonite [12] and electron spin resonance data confirmed chemisorption of Cu onto the hydroxyaluminum polymeric components of the pillared clay as well as evidence for electrostatically bound Cu 2+ .…”

“…Keizer and Bruggenwart [15] indicated that Cd adsorption by hydroxyaluminum-montmorillonite at pH 5.0 was an electrostatic process, but at pH 7.0 observed significant specific adsorption. Another research has indicated that a substantial portion of Cd is adsorbed by the interlayer material through specific adsorption [16][17][18].…”