In this process, 1.5 g of powder were weighed to fill different
100 mm high, 10 mm i.d. glass columns. Then 25 ml of the heavy
metal solution were added keeping the column close until complete
matrix humidification. After that, the column was open to allow
water flow and pressure was applied on the top of the column
using a syringe. From the elution, a sample (1.0 ml) was obtained,
labeled and stored for analysis and the rest was reloaded into the
column to test the amount of metal adsorbed after more than
one elution, all the experiments were done by triplicate.