Table 1 Amount of Cr(VI) immobilized within the column (Cr(VI)q, µmol), total Cr(VI) removal (mg/g) and Cr(VI) removal efficiency (%) calculated for different [Cr(VI)0], flow rates an inlet solution pH. Cr(VI) removal (mg/g) is the total amount of chromate immobilized (Cr(VI)q, mg) per grams of GRSO4 (9.1 mg) or S-nZVI (2.6 mg). Cr(VI) removal efficiency (%) is calculated assuming that GRSO4 and S-nZVI amended columns have 46.7 µmol (= 46.7 µmol Fe(II)) and 114 µmol (= 3 × 38 µmol Fe0) of reducing equivalents, respectively
Reactant type | [Cr(VI)0] (mM) | [Cr(VI)0] (mg/l) | pH | Q (ml/min) | Cr(VI)q (μmol) | Cr(VI)q (mg) | Cr(VI) removal (mg/g) | Cr(VI) removal efficiency (%) |
|---|---|---|---|---|---|---|---|---|
GRSO4 | 0.125 | 6.5 | 7 | 0.25 | 12.9 | 0.67 | 74.4 | 82.7 |
7 | 1 | 13.3 | 0.69 | 76.6 | 85.2 | |||
7 | 3 | 11.8 | 0.61 | 68.0 | 75.6 | |||
GRSO4 | 0.25 | 13 | 7 | 0.25 | 10.0 ± 0.1 | 0.52 ± 0.1 | 57.8 ± 0.3 | 64.3 ± 0.6 |
7 | 1 | 10.7 ± 0.1 | 0.55 ± 0.1 | 61.6 ± 0.3 | 68.4 ± 0.5 | |||
7 | 3 | 10.3 ± 0.3 | 0.53 ± 0.3 | 59.2 ± 1.8 | 65.9 ± 2.9 | |||
GRSO4 | 0.5 | 26 | 7 | 0.25 | 11.0 ± 0.8 | 0.57 ± 0.8 | 63.4 ± 4.5 | 70.5 ± 7.1 |
4.5 | 1 | 13.5 ± 0.3 | 0.70 ± 0.3 | 77.7 ± 1.6 | 86.4 ± 2.6 | |||
7 | 1 | 10.1 ± 0.1 | 0.52 ± 0.1 | 58.2 ± 0.5 | 64.8 ± 0.8 | |||
9.5 | 1 | 8.8 ± 0.7 | 0.46 ± 0.7 | 50.8 ± 4.2 | 56.5 ± 6.6 | |||
7 | 3 | 8.7 ± 0.7 | 0.45 ± 0.7 | 50.1 ± 3.7 | 55.7 ± 5.9 | |||
GRSO4 | 1 | 52 | 7 | 0.25 | 6.8 ± 0.6 | 0.35 ± 0.6 | 39.2 ± 3.2 | 43.5 ± 5.1 |
7 | 1 | 5.1 ± 0.7 | 0.26 ± 0.7 | 29.3 ± 3.8 | 32.6 ± 6.0 | |||
7 | 3 | 3.4 ± 0.1 | 0.18 ± 0.1 | 19.6 ± 0.5 | 21.8 ± 0.7 | |||
S-nZVI | 0.25 | 13 | 4.5 | 0.25 | 2.7 ± 0.1 | 0.14 | 53.4 ± 0.8 | 7.05 ± 0.9 |
7 | 0.25 | 1.3 ± 0.1 | 0.07 | 26.2 ± 0.5 | 3.47 ± 0.8 | |||
7 | 1 | 1.0 ± 0.1 | 0.05 | 20.7 ± 0.3 | 2.73 ± 0.5 | |||
7 | 3 | 1.1 ± 0.1 | 0.06 | 22.1 ± 0.4 | 2.91 ± 0.7 |