Ca2+/Na+ separation is a common problem in industrial applications,biological and medical fields.However,Ca2+ and Na+ have similar ionic radii and hydration radii,thus Ca2+/Na+ separation is challeng-ing.Inspired by biological channels,group modification is one of the effective methods to improve the separation performance.In this work,molecular dynamics simulations were performed to investigate the effects of different functional groups (COO-,NH3+) on the separation performance of Ca2+ and Na+through graphene nanopores under an electric field.The pristine graphene nanopore was used for com-parison.Results showed that three types of nanopores preferred Ca2+ to Na+,and Ca2+/Na+ selectivity fol-lowed the order of GE-COO (4.06) ＞ GE (1.85) ＞ GE-NH3+ (1.63).Detailed analysis of ionic hydration microstructure shows that different nanopores result in different hydration factors for the second hydra-tion layer of Ca2+ and the first layer of Na+.Such different hydration factors corresponding to the dehy-dration ability can effectively evaluate the separation performance.In addition,the breaking of hydrogen bonds between water molecules due to electrostatic effects can directly affect the dehydration ability.Therefore,the electrostatic effect generated by group modification will affect the ionic hydration microstructure,thus reflecting the differences in dehydration ability.This in turn affects the permeable and separation performance of cations.The results of this work provide perceptive guidelines for the application of graphene-based membranes in ion separation.

Yumeng Zhang;Yingying Zhang;Xueling Pan;Yao Qin;Jiawei Deng;Shanshan Wang;Qingwei Gao;Yudan Zhu;Zhuhong Yang;Xiaohua Lu

College of Chemical Engineering,State Key Laboratory of Materials-oriented Chemical Engineering,Nanjing Tech University,Nanjing 211816,China;College of Chemical Engineering,Nanjing Forestry University,Nanjing 210037,China;School of Chemical Engineering,State Key Laboratory of Chemical Engineering,East China University of Science and Technology,Shanghai 200237,China

中国化学工程学报（英文版）

[1]Yumeng Zhang;Yingying Zhang;Xueling Pan;Yao Qin;Jiawei Deng;Shanshan Wang;Qingwei Gao;Yudan Zhu;Zhuhong Yang;Xiaohua Lu-.Molecular insights on Ca2+/Na+ separation via graphene-based nanopores:The role of electrostatic interactions to ionic dehydration)[J].中国化学工程学报（英文版）,2022(01):220-229

Na+through,dration

Molecular,insights,Ca2+,separation,via,graphene,nanopores,role,electrostatic,interactions,ionic,dehydration,common,problem,industrial,applications,biological,medical,fields,However,have,similar,radii,thus,challeng,Inspired,by,channels,modification,one,methods,improve,performance,this,work,molecular,dynamics,simulations,were,performed,investigate,effects,different,functional,groups,COO,NH3+,under,electric,pristine,was,used,parison,Results,showed,that,three,types,preferred,selectivity,fol,lowed,order,GE,Detailed,analysis,microstructure,shows,factors,second,layer,first,Such,corresponding,ability,can,effectively,evaluate,addition,breaking,hydrogen,bonds,between,water,molecules,due,directly,Therefore,generated,will,reflecting,differences,This,turn,affects,permeable,results,provide,perceptive,guidelines,membranes

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