Table 3.
Adsorption capacity of select MNPs and their hybrids for select metalloids (As) and metal ions (i: initial; e: equilibrium; RT: room temperature; rpm: revolutions per minute of shaking; qe: equilibrium adsorption; qm: maximum adsorption capacity calculated using Langmuir isotherm; qm(L): maximum adsorption capacity calculated using Freundlich isotherm).
| Adsorbents | Reaction conditions | Adsorption capacity (mg g−1) |
Ref. |
|---|---|---|---|
| Fe3O4, 11.72 nm, 20 nm, 300 nm, 0.011–2.5 g L−1 | pH 4.8–8.0, [As]i 0–34 mg L−1, RT, 4 rpm, 24 h | qm As(V): 0.75–172 qm As(III): 1.6–135 | [280] |
| Fe3O4–γ-Fe2O3, 0.4 g L−1 | pH 2, [As(V)]i and [As(III)]i 1.5 mg L−1, [Cr(VI)]i 1.0 mg L−1, RT, 28 rpm, 24 h | Without phosphate qe As(V): 3.7 qe As(III): 3.7 qe Cr(VI): 2.4 With Phosphate at 3–5 mg L−1, adsorption decreased by 40–50% | [281] |
| Fe3O4–CTAB, Fe3O4, 0.1 g L−1 | pH 6.0, [As(V)]i 0.1–7 mg L−1, 25 °C, 200 rpm, 2 h | qm: 23 for Fe3O4–CTAB, qm: 7.6 for Fe3O4 only | [282] |
| Fe3O4–graphene-LDH, LDH, 0.5 g L−1 | pH 6.0, [As(V)]i 0–160 mg L−1, RT, shaking, 24 h | qm: 73 for Fe3O4–graphene-LDH qm: 38 for LDH | [283] |
| Fe3O4–GO, Fe3O4–rGO 0.1 g L−1 | pH 7, [Asi] 0–600 mg L−1, 25 °C, shaking but no rpm reported, 24 h | Fe3O4–GO qm As(V): 18.8 qm As(III): 42.9 Fe3O4–rGO qm As(V): 8.42 qm As(III): 29.8 | [284] |
| Fe3O4–starch, 1.0 g L−1 as Fe | pH 5.0, pH 6.9, [As(V)]i 38–617 mg L−1, RT, 200 rpm, 48 h | qe: 248 at pH 5.0 qe: 198 at pH 6.9 | [285] |
| AC–MnFe2O4 | Optimum pH 4.0 for As(V), pH 7.0 for As(III), 30 °C, 70 min | qm As(V): 1314 qm As(III): 1253 | [293] |
| Mesoporous Fe3O4, 2.0 g L−1 | pH 4.0 for Cr(VI), pH 5.0 for Pb2+, [M]i 0–100 mg L−1, 25 °C, 35 °C, 45 °C, | qm Pb2+: 13.4, 14.1, 18.5 qm Cr(VI): 6.64, 7.31, 8.90 | [318] |
| Fe3O4/Mg–Al–CO3–LDH, Mg–Al–CO3–LDH, 4.0 g L−1 | No pH adjusting, [Cd2+]e 0–200 mg L−1, 30–50 °C, 1–5 h, | qm Cd2+: 45.6–54.7 for Fe3O4/Mg–Al–CO3–LDH, qm Cd2+: 61.4–70.2 for Mg–Al–CO3–LDH | [82] |
| Fe3O4–humic acid, 0.01 g L−1 | pH 6.0, [M]i 0.01–5 mg L−1, 20 °C, stirring, 0.5 h | qm Cu2+: 46.3 qm Cd2+: 50.4 qm Pb2+: 92.4 qm Hg2+: 97.7 | [277] |
| DSMA–Fe3O4, 0.002 g L−1 | pH 8.1, [Hg2+]e 0–2 mg L−1 | qm Hg2+: 227 | [288] |
| SH–Fe3O4–NMPs, 0.5 g L−1 | pH 3.0, [Hg2+]i 20–500 mg L−1 | qm(L) Hg2+: 523 | [326] |
| Fe3O4–polyethylenimine, 1.0 g L−1 | pH 6, [M]i 0–5 mmol L−1, 23–25 °C, 150 rpm, 12 h | qm Zn2+: 68 qm Pb2+: 168 | [327] |
| N–MSU–F–S/Fe3O4, NN–MSU–F–S/Fe3O4, NNN–MSU–F–S/Fe3O4 | pH 5.75, pH 5.7, [M]i 10–200 mg L−1, RT, 10 rpm, 24 h | qm Pb2+: 222, 219, 191 qm Cu2+: 57.9, 50.6, 53.3 | [328] |
| Fe3O4–Si–N = Gelatin | pH 4.0 for Cd2+, pH 7.0 for Pb2+, RT, shaking but no rpm reported, 0.5 h | qe Cd2+: 49.5 qe Pb2+: 82.9 | [329] |
| MHC/OMCNTs | pH 5.0, [Pb2+]i 10–200 mg L−1 2h | qm Pb2+: 116 | [336] |
| ZnO/ZnFe2O4/C | qm Pb2+: 345 | [338] | |
| MnFe2O4–MoS2–CD, CoFe2O4–MoS2–CD, | pH 1–6, 25 °C | qm Pb2+: 588 qm Pb2+: 661 | [342] |
| Fe3O4@SiO2@chitosan | pH 5.4–8.5, [M]i 10 mg L−1, 25 °C, 4 h | qe Hg2+: 8.5–8.9 qe Pb2+: 6.0–6.9 qe Cu2+: 3.4–7.0 | [79] |