Table 3. Adsorption Performance of Different Adsorbents toward Azo-Dyes as Characterized by the Maximum Adsorption Capacity (mg dye/g Substrate).
| adsorbent | dye adsorbate | maximum capacity (mg/g) | references |
|---|---|---|---|
| granular activated carbon | Congo red | 9.1 | (55) |
| zeolite | DB 71 | 13.7 | (6) |
| graphene oxide | acid orange 8 | 29.0 | (11) |
| chitosan halloysite nanotubes | Congo red | 41.5 | (56) |
| multiwalled carbon nanotube | tartrazine | 84.0 | (57) |
| Mn0.4Zn0.6Fe2O4 nanoparticles | tartrazine | 90.8 | (58) |
| Mn0.4Zn0.6Fe2O4 nanoparticles | Ponceau 4R | 101.4 | (58) |
| SEG-modified starch | direct red 23 | 129.9 | (59) |
| SEG-modified starch | acid blue 92 | 147.1 | (59) |
| lignin amine-coated Fe3O4 | acid scarlet GR | 176.5 | (54) |
| chitosan | tartrazine | 350 | (60) |
| multiwalled carbon nanotube | DB 53 | 409.4 | (53) |
| graphene oxide sponge | direct red 80 | 501.3 | (5) |
| aminated CELF lignin | DB 1 | 502.7 | present |
| chitosan-based hydrogel | erichrome black T | 520 | (61) |
| carbon nanospheres | acid red 88 | 555.6 | (62) |
| Fe(OH)3@cellulose hybrid fibers | Congo red | 689.7 | (63) |