Figure 4

Adsorption percentage of Cr(III), Cu(II), Cd(II), and Pb(II) by CO (a), CL (b), ZO (c), ZL (d), FO (e) and FL (f) from the multiple-metal system at different contact times. Initial metal ions concentration of 0.18 mmol/L of metal, pH 4.0, and 25 mg of adsorbent.