2.2. Batch adsorption
Batch adsorption tests were conducted in 250mL continuously
stirred tank reactors at room temperature. One hundred
milliliter of the metal solution with 2 g of dry resins
were agitated at 120 rpm in an incubator shaker for 24 h.
This period was sufficient to achieve adsorption equilibrium.
Initial and equilibrium concentrations of metal solutions
were determined using a Varian SpectroAA atomic absorption
spectrophotometer using standard procedures. The amount
of metal adsorbed per unit mass of resin was calculated
from:
Qe = Ci − Ce
m
V (1)
where Ci and Ce are the initial and equilibrium metal concentrations
(mg/L), m the mass of resins (g) and V is the
volume of the metal-organic complex solutions (L). The
metals adsorbed on the resins were desorbed using 2M nitric
acid for 3 h under similar conditions used in the adsorption
tests. Regeneration efficiencies were determined from the
mass ratio of metal desorbed to that adsorbed by the resin at
equilibrium.