Research Article
Interaction of Natural Dye (Allium cepa) with Ionic Surfactants
Table 3
Surface parameters for interaction of dyes with surfactants at 25°C by surface tension measurement.
| | Surfactant | [Dye]
added
(g/L) | CMC
(mol dm−3) | Surface excess concentration
× 1010
(mol cm−2) | Area per molecule at interface
(A°)2 | pC
20 | −Δ
(kJ mol−1) | Δ
(JK−1 mol−1) | Δ
(J mol−1) | CMC/C 20 |
| CTAB
(0.02 g/L) | Nil | 9.6 × 10−4 | 2.19 | 75.8 | 3.07 | 36.59 | 122.78 | +1.07 | 1.12 | | 0.1 | 9.1 × 10−4 | 1.97 | 84.3 | 3.17 | 38.18 | 128.12 | −2.10 | 1.34 | | 0.2 | 8.6 × 10−4 | 1.75 | 94.3 | 3.35 | 40.49 | 135.85 | −2.49 | 1.92 | | 0.3 | 7.5 × 10−4 | 1.53 | 108.5 | 3.57 | 43.37 | 145.50 | −2.91 | 2.78 |
| NaLS
(0.20 g/L) | Nil | 8.1 × 10−3 | 1.97 | 84.3 | 2.17 | 32.47 | 108.97 | −2.96 | 1.19 | | 0.1 | 7.5 × 10−3 | 1.75 | 94.9 | 2.35 | 34.78 | 116.70 | −3.35 | 1.68 | | 0.2 | 6.5 × 10−3 | 1.53 | 108.5 | 2.49 | 37.22 | 124.80 | −3.85 | 2.01 | | 0.3 | 6.0 × 10−3 | 1.31 | 126.7 | 2.60 | 40.02 | 134.30 | −4.22 | 2.39 |
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