Table 1.
Classification of dyes and their corresponding properties, applications, and toxicities (Reproduced with permission [5]. Copyright 2015, Elsevier).
| Dyes | Properties | Applications | Toxicity | Examples |
|---|---|---|---|---|
| Acidic | Soluble in water, anionic | Nylon, wool, silk, paper, leather, ink-jet printing | Carcinogenic | Acid red 183, acid orange 10, acid orange 12, acid orange 8, acid red 73, acid red 18, sunset yellow, acid green 27, methyl orange, amido black 10B, indigo carmine |
| Cationic | Soluble in water, and liberates colored cations | Paper, PAN, treated nylons, treated polyesters, as antiseptic for biomedicine | Carcinogenic | MB, janus green, basic green 5, basic violet 10, rhodamine 6G |
| Disperse | Insoluble in water, non-ionic, for the aqueous/hydrophobic dispersions | Polyester, nylon, cellulose, cellulose acetate, acrylic fibers | Allergenic (skin), carcinogenic | Disperse orange 3, disperse red, disperse red 1, disperse yellow 1 |
| Direct | Soluble in water, anionic, promotes wash fastness in case chelated with metal salts | Cotton, regenerated cellulose, paper, leather | Bladder cancer | CR, direct red 23, direct orange 39, direct blue 86 |
| Reactive | Very high wash fastness thanks to its covalent bond with fiber, generates brighter colors compared to the direct dyes | Cotton, wool, nylon, ink-jet printing of textiles | Dermatitis, allergic conjunctivitis, rhinitis, occupational asthma | Reactive black 5, reactive green 19, reactive blue 4, reactive red 195, reactive red 198, reactive blue 19, reactive red 120 |
| Vat | employs soluble leuco salts following reduction in an alkaline bath (NaOH) | Cellulosic fibers | - | Vat blue 4, vat green 11, vat orange 15, vat orange 28, vat yellow 20 |