The capacity of CC and CS powders to remove metals (Hg2+ or
Hg2+and Cd2+) from spiked ultra-pure water was evaluated under
batch conditions, for different contamination scenarios. The
sorption kinetic experiments were carried out using as reaction
vessel a 2 L volumetric
flask, and by contacting a certain amount of
sorbent with the solution for a required period of time, under
constant magnetic stirring at room temperature (21
1 C) and
neutral pH (ca. 7). The scenarios studied were: (a) Hg concentrations
that equal the maximum legal limit allowed for
wastewater discharges that corresponds to 50 mg/L of Hg; (b) Hg
concentrations of 10 fold its maximum legal limit (500 mg/L); and
(c) Hg and Cd in concentrations that equal their maximum legal
limit allowed for wastewater discharges (respectively, 50 mg/L and
200 mg/L) [26]. A sorbent-free trial was run as a control, in order to
check metal losses that occurred by other means (e.g. adsorption
on the vessel walls, volatilization and/or retention by the Millipore
membrane during the
filtration step), rather than the sorption onto
the sorbents. To minimize metal adsorption to the containers and
avoid possible contaminations, all glassware used in the experi-
ments was acid-washed prior to use.