Table 6.
Recovery of REEs using CNTs and the respectively experimental conditions used as reported in the literature.
| Ref., Year |
Sorbent | Type of Water | Type of System | REEs (III) | [REEs]0 (µg/L) |
pH | T (°C) | Time of Contact (h) | m (sorbent)/ V(solution) (mg/L) |
qm (mg/g) or REEs Adsorption (%) |
|---|---|---|---|---|---|---|---|---|---|---|
| [98], 2017 |
CNTs-COOH | Ultrapure | Mono element | Sc | 300 × 103 | 2 4 |
r.t. | 4 | 50 × 102 | 37.9 mg/g 42.5 mg/g |
| [98], 2017 |
CNTs-COOH | Ultrapure | Mono element | Sc | (1–300) × 103 | 1–5.5 | r.t. | 0.02–0.5 | 50 × 102 | - |
| [106], 2013 |
MWCNTs-oxidized | Distilled | Multi elements | Ce | 20 × 103 20 × 103 10 × 103 |
5 | 30 | 2 | 12 × 102 10 × 102 10 × 102 |
~ 87% ~ 82% ~ 97% |
| [107], 2013 |
MWCNTs-oxidized | Distilled | Multi elements | Sm | 20 × 103 20 × 103 10 × 103 |
5 | 30 | 2 | 12 × 102 10 × 102 10 × 102 |
~ 98% ~ 95% ~ 100% |
| [107], 2013 |
MWCNTs-oxidized | Distilled | Multi elements | Ce, Sm |
(10, 20, 50, 75, 100, 150, 200) × 103 | 2–8 | 30, 40, 50, 60 | 0.08, 0.17, 0.25, 0.33, 0.5, 0.67, 0.83, 1, 1.25, 1.5, 2 | (2, 4, 6, 8, 10, 12) × 102 | - |
| [107], 2014 |
MWCNTs-oxidized | Distilled | Multi elements | La | 20 × 103 20 × 103 10 × 103 |
5 | 30 | 2 | 12 × 102 10 × 102 10 × 102 |
80% 80% 93% |
| [108], 2014 |
MWCNTs-oxidized | Distilled | Multi elements | Dy | 20 × 103 20 × 103 10 × 103 |
5 | 30 | 2 | 12 × 102 10 × 102 10 × 102 |
98% 97% 98% |
| [108], 2014 |
MWCNTs-oxidized | Distilled | Multi elements | La, Dy | (10–200) × 103 | 2–6 | 30, 40, 50, 60 | 0.08, 0.17, 0.25, 0.33, 0.5, 0.67, 0.83, 1, 1.25, 1.5, 2 | (2–12) ×102 |
|
| [112], 2011 |
TA-MWCNTs | Distilled | Multi elements | La Tb Lu |
40 × 103 | 5 | 20 | 1 | 50 × 102 | 5.35 mg/g, 8.55 mg/g, 3.97 mg/g |
| [113], 2011 |
TA-MWCNTs | Distilled | Mono element | La | 40 × 103 | 5 | 20 | 1 | 50 × 102
(with 0.12 × 102 being TA) |
75% |
| [113], 2011 |
TA-MWCNTs | Distilled | Multi elements | (La, Tb, Lu) | 40 × 103 | 1.5–4 | 20 | 1 | 50 × 102 | 0.4–6.0 mg/g |
| [113], 2011 |
TA-MWCNTs | Distilled | Multi elements | (La, Tb, Lu) | (5–50) × 103 | 1.5–7 | 20 | 0.08–2 | (20–200) × 102 | - |
| [110], 2009 |
MWCNTs-oxidized | Milli-Q | Mono element | Eu | 0.99 × 103 | 5 (2–8) |
25 | 96 | 6 × 102 | 90.0% |
| [109], 2009 |
MWCNTs/Fe3O4 composite | Milli-Q | Mono element | Eu a | 0.061 × 103 NaClO4 = 0.1 mol/L |
5.5 | 25 | 48 | 6 × 102 | ~ 100% |
| [110], 2009 |
MWCNTs/Fe3O4 composite | Milli-Q | Mono element | Eu a | 0.61 × 103, 6.1 × 103 |
2.5–7 | 25 | 48 | 6 × 102 | - |
| [105], 2015 |
PES/PVA/MWCNT/ D2EHPA beads | HCl (aq, 0.5 mol/L) |
Mono element | Y | 1000 × 103 | – | 30 | 8 | 1000 × 102 | 95% |
| [106], 2015 |
Y | (80–3300) × 103 | – | 30–65 | 0–8 | 1000 × 102 | 44.1 mg/g | |||
| [106], 2015 |
Multi elements | Y Sm La |
100 × 103 | – | 30 | 4 | 1000 × 102 | 94% 82% 30% |
||
| [106], 2015 |
PES/PVA/MWCNT/ D2EHPA beads | HCl (aq, 0.5 mol/L) |
Multi elements | Y, Sm, La | (150–1000) × 103 | – | 30 | 0–8 | 1000 × 102 | - |
| [111], 2008 |
MWCNTs-oxidized | Distilled | Mono element | Eu | 0.03 × 103 NaClO4 = 0.001, 0.01, 0.1 mol/L |
6 (2–7) |
25 | 48 | 6 × 102 | 98% for all the ionic strengths |
| [108], 2015 |
mIIP-CS/CNT composite | Distilled | Multi elements | Gd b | 10 × 103 | 7 | 20 33 43 |
4 | 20 × 102 c | 79.5 mg/g 109 mg/g 122 mg/g |
| [109], 2015 |
mNIP-CS/CNT composite | Distilled | Multi elements | Gd b | 10 × 103 | 7 | 33 | 4 | 20 × 102 c | 96.2 mg/g |
| [109], 2015 |
mIIP-CS/CNT and mNIP-CS/CNT composites | Distilled | Multi elements | Gd b | (2, 10, 50, 100, 200) × 103 | 2–7 | 20, 33, 43 | 0.05–8 | 20 × 102 c | - |
a Adsorptions experiments under N2 conditions. b Gd3+ adsorption experiments with two competitive ions (La3+ and/or Ce3+). c 10 mg of IIP-CS/CNT (or NIP-CS/CNT) and 30 mg of SiO2@Fe3O4 were added into a vial, which contained 20 mL of REEs. Optimal experimental conditions are represented by shading and the other conditions tested and described in the papers are represented on a white background (without shading).