Immobilization of Cr(VI) by sulphate green rust and sulphidized nanoscale zerovalent iron in sand media: batch and column studies

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 GR_SO4 (9.1 mg) or S-nZVI (2.6 mg). Cr(VI) removal efficiency (%) is calculated assuming that GR_SO4 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 (%)
GR_SO4	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
GR_SO4	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
GR_SO4	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
GR_SO4	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

ISSN: 1467-4866