| Adsorbent/metal ion | Qmax (mg/g) | Reference |
| C. vulgaris/Fe(Ill) | 24.491 | [30] |
| R. arrhizus/Fe(Ill) | 34.733 | [30] |
| Raw clinoptilolite/Fe(III) | 98.00 | [31] |
| Geobacillus thermodenitrificans/Fe(III) | 79.9 | [32] |
| SCB/Fe(III) | 331.1 | [33] |
| Orange peel/Fe(III) | 9.4308 | [34] |
| Date-pit/Al(III) | 5.831 | [35] |
| BDH activated carbon/Al(III) | 6.562 | [35] |
| R. opacus/Al(III) at 25˚C | 41.584 | [36] |
| RHAC/Fe(III) | 45.45 | Present study |
| RHAC/Al(III) | 34.48 | Present study |