期刊
CARBON
卷 164, 期 -, 页码 305-316出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.carbon.2020.04.018
关键词
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资金
- National Science Foundation of China [21878144, 21838004, 91934302, 21576130]
- Foundation for Innovative Research Groups of the National Natural Science Foundation of China [21921006]
- Project of Jiangsu Natural Science Foundation of China [BK20171464]
Residual Ca2+ decreases the efficiency and increases the power consumption of the chlor-alkali industry. However, Ca2+ and Na+ sieving is challenging due to the similar ionic radii of these cations. Inspired by the presence of carbonyl oxygens in key selective filters of biological Ca2+ and Na+ channels, we used molecular dynamics to investigate the effects of carbonyl oxygen atoms in modified graphene nanopores of various sizes (characteristic diameters: 0.57-1.50 nm) on Ca2+/Na+ sieving. The results demonstrated that selectivity is closely associated with the different roles of the carbonyl oxygen atoms. In small nanopores, Ca2+ sheds increased numbers of water molecules due to the predominant steric effect of carbonyl oxygen atoms. Thus, Ca2+ must overcome a higher energy barrier than Na+ . This requirement prevents the passage of Ca2+ . In large nanopores, carbonyl oxygen atoms do preferentially substitute water molecules outside the first hydration shell of Ca2+ compared with those outside the first hydration shell of Na+, thereby hindering Na+ departure from the nanopore. These findings provide useful guidance for the further development of Ca2+ separation materials as sensors and ion separators. (C) 2020 Elsevier Ltd. All rights reserved.
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