Sorption and desorption properties of Cadmium and Copper on soil clays in relation to charge characteristics

Abstract

Sorption and desorption properties of cadmium (Cd) and copper (Cu) in 5 clay types (montmorillonite, sericite, kaolinite, halloysite and allophane), which had been selected as representatives of commonly distributed minerals in the world soil environment, were investigated, with special reference to the charge characteristics of clays. Sorption properties of both Cd and Cu in all the clays were highly pH-dependent, resembling those in oxides. When the pH value at which 50% metal sorption on clays occurred was defined as pH-sorb 50 , the pH-sorb 50 values of Cd in the five clay types ranged between pH 5 and 7. Sericite exhibited the highest affinity for Cd sorption. In montmorillonite, sorbed Cd in the high pH region was not desorbed at all by subsequent extraction. For Cu, the pH-sorb 50 values were significantly lower than those for Cd, revealing the strong adsorption ability of Cu for all clay types. Sorption behavior of heavy metals was not parallel to the overall charge characteristics of clays and could not be easily predicted from the total charge such as cation exchange capacity or zeta potential. The higher sensitivity of 2:1 type clay minerals for Cd contamination was revealed. The critical role of edge surfaces on the sorption behavior was suggested because of the high charge density. The importance of pH control for the alleviation of Cd contamination was stressed for all clay types.

Use of porous volcanic rocks for the adsorptive removal of copper

“…; Alemayehu & Lennartz ). The result was in support of the observations that bentonite clay, montmorillonite, sericite, kaolinite, halloysite and allophane clays revealed the strong adsorption ability of Cu(II) over Cd(II) (Itami & Yanai ; Helena et al . ).…”

“…This could be due to the valuable properties of VPum such as surfaceexposed ionic charge, porosity, wearability and surface area (Skoog et al 2004;Yavuz et al 2008;Alemayehu & Lennartz 2009). The result was in support of the observations that bentonite clay, montmorillonite, sericite, kaolinite, halloysite and allophane clays revealed the strong adsorption ability of Cu(II) over Cd(II) (Itami & Yanai 2006;Helena et al 2011).…”

Persistence of CaCl2washing effect for amelioration of a Cd-contaminated paddy field soil

“…1984; Kuo et al . 2006) and clay suspensions (Itami and Yanai 2006) are enhanced under acidic conditions. The efficiency of Cd extraction from soil using CaCl 2 is attributable to cation exchange reaction on the negatively charged sites, and to formation of stable dissolved complexes of Cd and Cl (Hattori et al .…”

“…The mobility of Cd in soil depends on the soil pH. The solubility and extractability of Cd in soils (Filius et al 1998;Gerritse et al 1984;Kuo et al 2006) and clay suspensions (Itami and Yanai 2006) are enhanced under acidic conditions. The efficiency of Cd extraction from soil using CaCl 2 is attributable to cation exchange reaction on the negatively charged sites, and to formation of stable dissolved complexes of Cd and Cl (Hattori et al 2006;Norvell et al 2000;Weggler et al 2004).…”

High decrease in soil metal bioavailability by metal immobilization with halloysite clay

“…Halloysite as well as other clay minerals can be used for adsorption of different harmful substances. Different clay types can be applied for sorption and desorption of cadmium and copper (Itami and Yanai 2006). A surface modified with hexadecyltrimethylammonium bromide is effective for chromium(VI) adsorption (Jinhuaa et al 2010), while chemical modification with N-2-pyridylsuccinamic acid (He et al 2013) gives a suitable sorbent for lead(II) in solid phase extraction.…”