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Title: Novel Polyethylenimine–Acrylamide/SiO 2 Hybrid Hydrogel Sorbent for Rare-Earth-Element Recycling from Aqueous Sources

Recycling rare earth elements (REEs) becomes increasingly important due to their supply vulnerability and increasing demands in industry, agriculture, and national security. Hybrid hydrogel sorbents were outstanding due to their high stability and selectivity. Organic-inorganic hybrid hydrogels were synthesized by thermo-polymerization of acrylamide onto PEI polymer chain with N,N’-methylene bisacrylamide as a crosslinker. The grafted network was evidenced by DRIFTS and XPS. The porous structure was observed by SEM. Crosslink degree, PEI grafting degree, and SiO 2 concentration were studied to optimize the REEs adsorption. The pH value of the medium greatly affected REE adsorption capacity, where the nearly neutral conditions gave the strongest bonding of REEs to active sites. Moreover, kinetic studies showed that the rate-determining step of the adsorption process was chemical sorption, and that REE diffusion within micropores was the control step for, specifically, intraparticle diffusion. The adsorbents showed excellent selectivity and recyclability for REEs through 5 adsorption-desorption cycles in contact with synthetic acid mine drainage solution. A high separation toward REEs over fouling metals was achieved by using a citrate-based buffer eluent solution. This hybrid hydrogel shows promise for the recycling of REEs from aqueous solutions.
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [2] ;  [2] ;  [3]
  1. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); AECOM, Pittsburgh, PA (United States)
  3. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)
Publication Date:
Report Number(s):
NETL-PUB-21238
Journal ID: ISSN 2168-0485
Type:
Accepted Manuscript
Journal Name:
ACS Sustainable Chemistry & Engineering
Additional Journal Information:
Journal Volume: 5; Journal Issue: 11; Journal ID: ISSN 2168-0485
Publisher:
American Chemical Society (ACS)
Research Org:
National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)
Sponsoring Org:
USDOE Office of Fossil Energy (FE)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1433646
Alternate Identifier(s):
OSTI ID: 1440525

Wang, Qiuming, Wilfong, Walter C., Kail, Brian W., Yu, Yang, and Gray, McMahan L.. Novel Polyethylenimine–Acrylamide/SiO2 Hybrid Hydrogel Sorbent for Rare-Earth-Element Recycling from Aqueous Sources. United States: N. p., Web. doi:10.1021/acssuschemeng.7b02851.
Wang, Qiuming, Wilfong, Walter C., Kail, Brian W., Yu, Yang, & Gray, McMahan L.. Novel Polyethylenimine–Acrylamide/SiO2 Hybrid Hydrogel Sorbent for Rare-Earth-Element Recycling from Aqueous Sources. United States. doi:10.1021/acssuschemeng.7b02851.
Wang, Qiuming, Wilfong, Walter C., Kail, Brian W., Yu, Yang, and Gray, McMahan L.. 2017. "Novel Polyethylenimine–Acrylamide/SiO2 Hybrid Hydrogel Sorbent for Rare-Earth-Element Recycling from Aqueous Sources". United States. doi:10.1021/acssuschemeng.7b02851. https://www.osti.gov/servlets/purl/1433646.
@article{osti_1433646,
title = {Novel Polyethylenimine–Acrylamide/SiO2 Hybrid Hydrogel Sorbent for Rare-Earth-Element Recycling from Aqueous Sources},
author = {Wang, Qiuming and Wilfong, Walter C. and Kail, Brian W. and Yu, Yang and Gray, McMahan L.},
abstractNote = {Recycling rare earth elements (REEs) becomes increasingly important due to their supply vulnerability and increasing demands in industry, agriculture, and national security. Hybrid hydrogel sorbents were outstanding due to their high stability and selectivity. Organic-inorganic hybrid hydrogels were synthesized by thermo-polymerization of acrylamide onto PEI polymer chain with N,N’-methylene bisacrylamide as a crosslinker. The grafted network was evidenced by DRIFTS and XPS. The porous structure was observed by SEM. Crosslink degree, PEI grafting degree, and SiO2 concentration were studied to optimize the REEs adsorption. The pH value of the medium greatly affected REE adsorption capacity, where the nearly neutral conditions gave the strongest bonding of REEs to active sites. Moreover, kinetic studies showed that the rate-determining step of the adsorption process was chemical sorption, and that REE diffusion within micropores was the control step for, specifically, intraparticle diffusion. The adsorbents showed excellent selectivity and recyclability for REEs through 5 adsorption-desorption cycles in contact with synthetic acid mine drainage solution. A high separation toward REEs over fouling metals was achieved by using a citrate-based buffer eluent solution. This hybrid hydrogel shows promise for the recycling of REEs from aqueous solutions.},
doi = {10.1021/acssuschemeng.7b02851},
journal = {ACS Sustainable Chemistry & Engineering},
number = 11,
volume = 5,
place = {United States},
year = {2017},
month = {9}
}