In Erlenmeyer flask (125 mL) containing the adsorbent
material were added 50 mL of aqueous solution enriched
with heavy metals in the following concentrations: Cd
(0.05 mg mL-1), Pb (0.10 mg mL-1), Cr (0.50 mg m-1). The
concentration chosen for each metal studied in this stage was
10 times the maximum allowed value in accordance with
Ordinance No. 518 from the Brazilian Health Ministry, which
establishes procedures and responsibilities relating to control
and surveillance of water quality for human drinking and its
potability standards (Brasil, 2004).