Table 3. Parameters of the Pseudo-Second-Order Model for the Adsorption of Zn(II), Pb(II), Cd(II), and Hg(II) on PSPa.
| metal ion | ionic radius (Å) | hydrated radius (Å) | qe (cal) (mmol/g) | K2 (g/mg min) | qe (exp) (mmol/g) | R2 |
|---|---|---|---|---|---|---|
| Zn(II) | 0.74 | 4.30 | 1.73 | 7.2 × 10–3 | 1.71 | 0.997 |
| Pb(II) | 1.19 | 4.01 | 0.44 | 8.4 × 10–3 | 0.43 | 0.993 |
| Cd(II) | 0.95 | 4.26 | 0.69 | 6.9 × 10–3 | 0.66 | 0.990 |
| Hg(II) | 1.02 | 4.22 | 0.24 | 7.3 × 10–3 | 0.22 | 0.984 |
a
Batch conditions: initial metal concentration: 100 mg/L; temperature: 298 K; pH: 6.5; adsorbent dose: 25 mg; solution volume: 40 mL.