张为, 杨斌, 蔡伊, 易俊年, 张杰. 水溶液中NaF缔合行为的分子动力学研究[J]. 云南大学学报(自然科学版), 2019, 41(4): 772-779. doi: 10.7540/j.ynu.20180726
引用本文: 张为, 杨斌, 蔡伊, 易俊年, 张杰. 水溶液中NaF缔合行为的分子动力学研究[J]. 云南大学学报(自然科学版), 2019, 41(4): 772-779. doi: 10.7540/j.ynu.20180726
ZHANG Wei, YANG Bin, CAI Yi, YI Jun-nian, ZHANG Jie. Molecular dynamics study on the association behavior of NaF in aqueous solution[J]. Journal of Yunnan University: Natural Sciences Edition, 2019, 41(4): 772-779. DOI: 10.7540/j.ynu.20180726
Citation: ZHANG Wei, YANG Bin, CAI Yi, YI Jun-nian, ZHANG Jie. Molecular dynamics study on the association behavior of NaF in aqueous solution[J]. Journal of Yunnan University: Natural Sciences Edition, 2019, 41(4): 772-779. DOI: 10.7540/j.ynu.20180726

水溶液中NaF缔合行为的分子动力学研究

Molecular dynamics study on the association behavior of NaF in aqueous solution

  • 摘要: 氟是自然界中广泛存在、与人体健康密切相关的元素,其在溶液中物种类型对评价地下水中氟的迁移转化和处理含氟废水具有重要的作用. 该文运用经典分子动力学,采用伞形采样方法计算了25 ℃ NaF水溶液中Na+−F离子对的平均力势,以此判断NaF的缔合类型和计算其缔合常数. 结果显示NaF溶液中同时存在直接接触型离子对(CIP)、溶剂共享型离子对(SSHIP)和溶剂分隔型离子对(SSIP)3种缔合类型,其中CIP和SSHIP是溶液中最稳定存在的2种类型. 但是就相对含量而言,NaF溶液的缔合类型以SSHIP和SSIP为主,CIP只占4.2%. 计算得到NaF的缔合反应平衡常数为2.271,与实验结果吻合较好. NaF浓度对Na+−F的径向分布函数和配位数有很大影响,但是对各缔合类型的相对含量影响不大.

     

    Abstract: Fluoride is an element closely related to the health of organisms. Sodium fluoride is the most common fluoride salt in nature. The study of its speciation in solution plays an important role in evaluating the migration and conversion of fluorine in groundwater and the treatment of fluorine−containing wastewater. In this paper, using classical molecular dynamics, the potential of mean force (PMF) of Na+−F ions pair was calculated by Umbrella Sampling. The association type and association constant at 25 ℃ were determined with the calculated PMF. The results show that there are three association types of CIP, SSHIP and SSIP in NaF solution, among which CIP and SSHIP are the two most stable types. However, in terms of relative content, the association type of sodium fluoride solution is mainly SSHIP and SSIP, and CIP only accounts for 4.2%. The calculated equilibrium constant of NaF is 2.271, which is in good agreement with the experimental results. The NaF concentration has a great influence on the radial distribution function and coordination number of Na+−F, but a little effect on the relative content.

     

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