and at adjusted pHs were transferred into 250 mL
Erlenmeyer flasks. Pre-defined amounts of the sorbent were added
to these solutions. After 24 h, solutions were filtered and metal ion
concentrations in the filtrate were determined. Concentrations of
metal ions in samples were determined by atomic absorption
spectroscopy (AAS). Concentration of metal retained in the sorbent
phase (qe, mg/g) was calculated from the expression: