8
SUMMARY AND CONCLUSION
This study examined the effectiveness of deep eutectic sol-
vents (DESs) as reagents for extracting rare earth elements
(REE). The leaching investigation revealed that the dissolu-
tion of REEs in DES increased over time in Oxaline, Lactic
Acid-Choline Chloride, and Reline. However, the recovery
of analyzed REEs did not improve with time in Ethaline
and Glycerol-Choline Chloride DES.
In Lactic Acid-choline chloride DES, the recovery of
cerium (Ce) increased with time, while both lanthanum
and neodymium showed slight increases over the same
period, with praseodymium showing no increase. In oxa-
line DES, the recoveries of cerium (Ce), lanthanum (La),
praseodymium (Pr), and neodymium (Nd) increased con-
sistently over time.
The recovery order of the analyzed REEs is as follows: in
Oxaline, Lactic Acid-Choline Chloride, and Reline DES, it
is Cerium Lanthanum Neodymium Praseodymium,
whereas in Ethaline and Glycerol-Choline Chloride, it is
Praseodymium Neodymium Lanthanum cerium.
The best solvents for dissolving the examined REEs are
Oxaline and Lactic Acid-Choline Chloride, with cerium
recovery rates peaking at 25% and 15%, respectively. In
contrast, Ethaline and Glycerol-Choline Chloride DES
yielded a maximum recovery of only about 2% for praseo-
dymium, indicating less effective leaching. This suggests
that the success of the leaching process is influenced by the
specific chemical characteristics of each DES.
RECOMMENDATION AND
FUTURE WORKS
Further work on varying the temperature and increasing
leaching time would be done to obtain more data and bet-
ter understand the recovery of the analyzed REEs in the
selected DESs used for this research.
Further investigation is required to understand why
Reline, Glycerol-Choline Chloride, and Ethaline did not
undergo leaching, in contrast to Oxaline and Lactic Acid-
Choline Chloride.
After determining the best DES for the analyzed REEs,
in-depth assessments will be conducted, including solid
residue analysis, operating parameters, and leaching kinet-
ics, to evaluate the impact of process conditions on total
REE recovery.
All ongoing work for this research will be completed to
have complete data and information on the dissolution of
REEs in DES media.
REFERENCES
[1] S. Peelman, Z. H. I. Sun, J. Sietsma, and Y. Yang,
“Leaching of Rare Earth Elements: Review of Past
and Present Technologies,” in Rare Earths Industry:
Technological, Economic, and Environmental
Implications, Elsevier Inc., 2015, pp. 319–334. DOI:
10.1016/B978-0-12-802328-0.00021-8.
[2] T. Dutta et al., “Global demand for rare earth resources
and strategies for green mining.,” Environ Res, vol.
150, pp. 182–190, Oct. 2016, DOI: 10.1016/J.
ENVRES.2016.05.052.
[3] H. X. Mai et al., “High-quality sodium rare-earth flu-
oride nanocrystals: Controlled synthesis and optical
properties,” J Am Chem Soc, vol. 128, no. 19, pp. 6426–
6436, May 2006, DOI: 10.1021/JA060212H
/SUPPL_FILE/JA060212HSI20060414_124908
.PDF.
[4] H. Abdollahi et al., “Superadsorbent Fe3O4-coated
carbon black nanocomposite for separation of light
rare earth elements from aqueous solution: GMDH-
based Neural Network and sensitivity analysis,”
J Hazard Mater, vol. 416, Aug. 2021, DOI: 10.1016/j.
jhazmat.2021.125655.
[5] L. Omodara, S. Pitkäaho, E. M. Turpeinen, P.
Saavalainen, K. Oravisjärvi, and R. L. Keiski,
“Recycling and substitution of light rare earth ele-
ments, cerium, lanthanum, neodymium, and
praseodymium from end-of-life applications -A
review,” Nov. 2019, Elsevier Ltd. DOI: 10.1016
/j.jclepro.2019.07.048.
0 1 2 3 4 5 6 7 8 9
0
5
10
15
20
25
30
Time/ Hours
Ce- Glycerol-ChCl(80°C)
La- Glycerol-ChCl(80°C)
Nd- Glycerol-ChCl(80°C)
Pr- Glycerol-ChCl(80°C)
Figure 11. %Recovery of Cerium, Lanthanum, Neodymium,
and Praseodymium during leaching in Glycerol-Choline
Chloride DES at 80°C
%
Recovery
SUMMARY AND CONCLUSION
This study examined the effectiveness of deep eutectic sol-
vents (DESs) as reagents for extracting rare earth elements
(REE). The leaching investigation revealed that the dissolu-
tion of REEs in DES increased over time in Oxaline, Lactic
Acid-Choline Chloride, and Reline. However, the recovery
of analyzed REEs did not improve with time in Ethaline
and Glycerol-Choline Chloride DES.
In Lactic Acid-choline chloride DES, the recovery of
cerium (Ce) increased with time, while both lanthanum
and neodymium showed slight increases over the same
period, with praseodymium showing no increase. In oxa-
line DES, the recoveries of cerium (Ce), lanthanum (La),
praseodymium (Pr), and neodymium (Nd) increased con-
sistently over time.
The recovery order of the analyzed REEs is as follows: in
Oxaline, Lactic Acid-Choline Chloride, and Reline DES, it
is Cerium Lanthanum Neodymium Praseodymium,
whereas in Ethaline and Glycerol-Choline Chloride, it is
Praseodymium Neodymium Lanthanum cerium.
The best solvents for dissolving the examined REEs are
Oxaline and Lactic Acid-Choline Chloride, with cerium
recovery rates peaking at 25% and 15%, respectively. In
contrast, Ethaline and Glycerol-Choline Chloride DES
yielded a maximum recovery of only about 2% for praseo-
dymium, indicating less effective leaching. This suggests
that the success of the leaching process is influenced by the
specific chemical characteristics of each DES.
RECOMMENDATION AND
FUTURE WORKS
Further work on varying the temperature and increasing
leaching time would be done to obtain more data and bet-
ter understand the recovery of the analyzed REEs in the
selected DESs used for this research.
Further investigation is required to understand why
Reline, Glycerol-Choline Chloride, and Ethaline did not
undergo leaching, in contrast to Oxaline and Lactic Acid-
Choline Chloride.
After determining the best DES for the analyzed REEs,
in-depth assessments will be conducted, including solid
residue analysis, operating parameters, and leaching kinet-
ics, to evaluate the impact of process conditions on total
REE recovery.
All ongoing work for this research will be completed to
have complete data and information on the dissolution of
REEs in DES media.
REFERENCES
[1] S. Peelman, Z. H. I. Sun, J. Sietsma, and Y. Yang,
“Leaching of Rare Earth Elements: Review of Past
and Present Technologies,” in Rare Earths Industry:
Technological, Economic, and Environmental
Implications, Elsevier Inc., 2015, pp. 319–334. DOI:
10.1016/B978-0-12-802328-0.00021-8.
[2] T. Dutta et al., “Global demand for rare earth resources
and strategies for green mining.,” Environ Res, vol.
150, pp. 182–190, Oct. 2016, DOI: 10.1016/J.
ENVRES.2016.05.052.
[3] H. X. Mai et al., “High-quality sodium rare-earth flu-
oride nanocrystals: Controlled synthesis and optical
properties,” J Am Chem Soc, vol. 128, no. 19, pp. 6426–
6436, May 2006, DOI: 10.1021/JA060212H
/SUPPL_FILE/JA060212HSI20060414_124908
.PDF.
[4] H. Abdollahi et al., “Superadsorbent Fe3O4-coated
carbon black nanocomposite for separation of light
rare earth elements from aqueous solution: GMDH-
based Neural Network and sensitivity analysis,”
J Hazard Mater, vol. 416, Aug. 2021, DOI: 10.1016/j.
jhazmat.2021.125655.
[5] L. Omodara, S. Pitkäaho, E. M. Turpeinen, P.
Saavalainen, K. Oravisjärvi, and R. L. Keiski,
“Recycling and substitution of light rare earth ele-
ments, cerium, lanthanum, neodymium, and
praseodymium from end-of-life applications -A
review,” Nov. 2019, Elsevier Ltd. DOI: 10.1016
/j.jclepro.2019.07.048.
0 1 2 3 4 5 6 7 8 9
0
5
10
15
20
25
30
Time/ Hours
Ce- Glycerol-ChCl(80°C)
La- Glycerol-ChCl(80°C)
Nd- Glycerol-ChCl(80°C)
Pr- Glycerol-ChCl(80°C)
Figure 11. %Recovery of Cerium, Lanthanum, Neodymium,
and Praseodymium during leaching in Glycerol-Choline
Chloride DES at 80°C
%
Recovery