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Title: Influence of hydrophilic groups and metal-ion adsorption on polymer-chain conformation of amidoxime-based uranium adsorbents

Abstract

In this study, we focus on the influence of hydrophilic groups and metal-ion loading on adsorbent polymer conformation, which controls access to adsorption sites and may limit adsorption capacity. Gaining a better understanding of the factors that influence conformation may yield higher-capacity adsorbents. Polyamidoxime (PAO), deuterated-PAO polyacrylic acid diblock copolymers (d-PAO-b-PAA), and randomly configured copolymers (PAO-co-PAA) were synthesized and characterized by neutron reflectometry in air and D 2O. For d-PAO-b-PAA, characterization was also performed after alkali conditioning and in simulated seawater. PAO and PAO-co-PAA, with similar molecular weight and grafting density, extended from 95-Å thickness in air to 180 and 280-Å in D 2O, respectively. This result suggests that polymer swelling may cause the additional adsorption capacity observed when polymer hydrophilicity increases. Two d-PAO-b-PAA samples, A and B, with a d-PAO thickness of 55-Å swelled to 110-Å and 140-Å, respectively, with an overall thickness increase of ~160% in D 2O. After alkali conditioning, molecular interactions increased the density of PAA near the PAO-PAA interface, while the d-PAO thickness only decreased by ~10 Å. The d-PAO thickness of both samples declined to ~90-Å after adsorption in simulated seawater due to polymer-chain crosslinking. In conclusion, these results are expected to aid inmore » improving adsorbent synthesis to increase uranium capacity.« less

Authors:
 [1];  [2]; ORCiD logo [2];  [2];  [1]; ORCiD logo [2]; ORCiD logo [2]
  1. Georgia Inst. of Technology, Atlanta, GA (United States). School of Civil and Environmental Engineering
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Nuclear Energy (NE)
OSTI Identifier:
1439934
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Colloid and Interface Science
Additional Journal Information:
Journal Volume: 524; Journal Issue: C; Journal ID: ISSN 0021-9797
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; Neutron reflectometry; Amidoxime; Polymer conformation; Uranium; Seawater

Citation Formats

Wiechert, Alexander I., Liao, Wei-Po, Hong, Eunice K., Halbert, Candice E., Yiacoumi, Sotira, Saito, Tomonori, and Tsouris, Costas. Influence of hydrophilic groups and metal-ion adsorption on polymer-chain conformation of amidoxime-based uranium adsorbents. United States: N. p., 2018. Web. doi:10.1016/j.jcis.2018.04.021.
Wiechert, Alexander I., Liao, Wei-Po, Hong, Eunice K., Halbert, Candice E., Yiacoumi, Sotira, Saito, Tomonori, & Tsouris, Costas. Influence of hydrophilic groups and metal-ion adsorption on polymer-chain conformation of amidoxime-based uranium adsorbents. United States. doi:10.1016/j.jcis.2018.04.021.
Wiechert, Alexander I., Liao, Wei-Po, Hong, Eunice K., Halbert, Candice E., Yiacoumi, Sotira, Saito, Tomonori, and Tsouris, Costas. Fri . "Influence of hydrophilic groups and metal-ion adsorption on polymer-chain conformation of amidoxime-based uranium adsorbents". United States. doi:10.1016/j.jcis.2018.04.021.
@article{osti_1439934,
title = {Influence of hydrophilic groups and metal-ion adsorption on polymer-chain conformation of amidoxime-based uranium adsorbents},
author = {Wiechert, Alexander I. and Liao, Wei-Po and Hong, Eunice K. and Halbert, Candice E. and Yiacoumi, Sotira and Saito, Tomonori and Tsouris, Costas},
abstractNote = {In this study, we focus on the influence of hydrophilic groups and metal-ion loading on adsorbent polymer conformation, which controls access to adsorption sites and may limit adsorption capacity. Gaining a better understanding of the factors that influence conformation may yield higher-capacity adsorbents. Polyamidoxime (PAO), deuterated-PAO polyacrylic acid diblock copolymers (d-PAO-b-PAA), and randomly configured copolymers (PAO-co-PAA) were synthesized and characterized by neutron reflectometry in air and D2O. For d-PAO-b-PAA, characterization was also performed after alkali conditioning and in simulated seawater. PAO and PAO-co-PAA, with similar molecular weight and grafting density, extended from 95-Å thickness in air to 180 and 280-Å in D2O, respectively. This result suggests that polymer swelling may cause the additional adsorption capacity observed when polymer hydrophilicity increases. Two d-PAO-b-PAA samples, A and B, with a d-PAO thickness of 55-Å swelled to 110-Å and 140-Å, respectively, with an overall thickness increase of ~160% in D2O. After alkali conditioning, molecular interactions increased the density of PAA near the PAO-PAA interface, while the d-PAO thickness only decreased by ~10 Å. The d-PAO thickness of both samples declined to ~90-Å after adsorption in simulated seawater due to polymer-chain crosslinking. In conclusion, these results are expected to aid in improving adsorbent synthesis to increase uranium capacity.},
doi = {10.1016/j.jcis.2018.04.021},
journal = {Journal of Colloid and Interface Science},
number = C,
volume = 524,
place = {United States},
year = {Fri Apr 06 00:00:00 EDT 2018},
month = {Fri Apr 06 00:00:00 EDT 2018}
}

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