Dissolution of mercury from amalgams and some intermetallic compounds found in the amalgam structure, such as gamma 1, gamma 2, and beta 1, was examined during one week of aging in 0.9% NaCl solution at 37 degrees C. The amount of mercury released from gamma 1 (30.2 micrograms/cm2) was at least 13 times that released from amalgam (0.5-2.2 micrograms/cm2) and five times that released from beta 1(5.7 micrograms/cm2). Gamma 2 released the least amount of mercury (0.46 micrograms/cm2). The study revealed that as high as 55% of the mercury ions liberated from the amalgams and the amalgam phases was adsorbed onto the walls of the vials in which the specimens were aged.
This paper assesses the potential of modified montmorillonite clays as low-cost adsorbents/ion-exchangers for the removal of trace level heavy metals (Cd, Cu, Ni, Pb and Zn) from potable water. Modification of the montmorillonites resulted in the exchange of the interlayer calcium ions for the polymeric species. One unmodified montmorillonite and three polymeric Fe- and Al-modified montmorillonites have been evaluated with respect to their selectivity and uptake performance. All of the clays are selective for Pb and Cu adsorption from aqueous solutions at the mildly acidic pH range in which the experiments were performed (pH 5.5–6). Polymeric iron- and polymeric Al/Fe-modified clays had comparatively great affinities for all the metals studied, whilst the original and polymeric Al modified clays had relatively lower affinities. Only the uptake of Pb and Cu could be correlated with physical properties such as clay surface area. The metal selectivity could be correlated to the type of intercalated polymeric Fe and Al species of the modified clays
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