拉曼光谱法研究Na^+,Mg^(2+)//SO_4^(2-),Cl^-,H_2O四元体系中SO_4^(2-)离子缔合结构特征及其变化规律  

Studies on the Characteristics and Behaviors of the Ion Association Structures of SO_4^(2-) in Na^+,Mg^(2+)//SO_4^(2-),Cl^-,H_2O System by Raman Spectroscopy

作　　者：阎波[1] 周桓[2] 李文轩[2] 

机构地区：[1]天津科技大学海洋与环境学院天津市海洋资源与化学重点实验室,天津300457 [2]天津科技大学化工与材料学院天津市海洋资源与化学重点实验室,天津300457

出　　处：《物理化学学报》2016年第2期405-414,共10页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(21176189;U1407204);天津市应用基础与前沿技术研究计划(15JCYBJC23200);教育部科研创新团队培育计划([2013]373);天津市高等学校创新团队培养计划(TD12-5004)资助项目~~

摘　　要：复杂水盐体系存在稳态和介稳固液相平衡以及复杂的成盐规律。为了解固液平衡状态下液相的结构特征,本文采用拉曼光谱技术并结合高斯-洛伦兹去卷积分峰拟合程序对Na^+,Mg^(2+)//SO_4^(2-),Cl^-,H_2O四元体系及其二元和三元子体系中v_1-SO_4^(2-)的离子缔合结构特征进行了分析。研究结果表明:SO_4^(2-)在Na_2SO_4-H_2O体系存在自由态SO_4^(2-)和SO_4^(2-)离子簇两种结构,在Mg_2SO_4-H_2O,MgSO_4-MgCl_2-H_2O及Na^+,Mg^(2+)//SO_4^(2-),Cl^-,H_2O等含镁体系中,还有Mg^(2+)-H_2O-SO_4^(2-)和Mg^(2+)-OSO_3^(2-)两种缔合结构。在二元和三元体系中V_1-SO_4^(2-)的离子缔合结构以自由态SO_4^(2-)为主,随着SO_4^(2-)离子总浓度的变化,上述四种结构所占比例会发生规律性变化。Na^+,Mg^(2+)//SO_4^(2-),Cl^-,H_2O四元体系在NaCl减少及等温蒸发过程中,自由态SO_4^(2-)结构比例逐步降低,Mg2+和SO_4^(2-)相结合形成Mg^(2+)-H_2O-SO_4^(2-)或Mg^(2+)-OSO_3^(2-)结构的机会增多,在复盐区还会形成SO_4^(2-)离子簇结构。由此判断溶液结构的适应性变化是导致介稳现象的重要原因。进一步的相关分析表明:SO_4^(2-)的浓度和耶涅克指数J与V_1-SO_4^(2-)峰的峰强度和峰面积存在正相关关系,Mg^(2+)浓度是影响V_1-SO_4^(2-)峰中四种缔合结构的比例发生变化的主要因素。Stable and metastable solid-liquid equilibria phenomena and complex salt-forming behaviors exist in complex salt-water systems.To realize the relationship between salt-forming behavior and liquid structure,the characteristics of ion association structures of SO4^2- in Na^＋,Mg^2＋ // SO4^2-,CI^-,H2O system and its binary,ternary subsystems were studied by Raman spectroscopy,combined with a Gauss-Lorentz peak fitting program.The spectrum experimental results show that there were two ion association structures of SO4^2- as nonassociated SO4^2- and SO4^2- groups in the Na2SO4-H2O system,while in the MgSO4-H2O,MgSO4-MgCI2-H2O,and Na^＋,Mg^2＋-//SO4^2--,Cl^-,H2O systems,there were also Mg^2＋-H2O-SO4^2- and Mg^2＋-OSO3^2- structures.Non-associated SO4^2- was the main structure in the v1-SO4^2- band of binary（MgSO4 Na2SO4） and ternary（MgSO4-MgCI2-H2O）subsystems,and with varying SO4^2- concentration,these four types of SO4^（2-） ion association structure varied regularly.Likewise,the ion association structures of SO4^（2-） in the Na~＋,Mg^（2＋） // SO4^（2-）,Cl^-,H2O system changed regularly during both the processes of NaCl crystallization and isothermal evaporation.This was evident when,during the process of decreasing NaCl concentration and increasing MgSO4,the content of non-associated SO4^2-decreased,the chance of Mg^2＋-H2O-SO4^2-and Mg^2＋-OSO3^2- structure formation increased,and the SO4^2-group structure appeared in the astrachanite region.More importantly,the adaptive changes in solution structure during the progress of evaporation can result in the appearance of metastable phenomena.Further linear analysis showed that the concentration and Janecke index（J） value of SO4^（2-） were positively related to the intensity and peak area of the V1-SO4^（2-） band,and the concentration of Mg^（2＋） affected the contents of four ion association structures in the v1-SO4^（2-） band mainly.

关 键 词：SO4^2- 离子缔合结构 拉曼光谱 固液相平衡 

分 类 号：O657.37[理学—分析化学] TS31[理学—化学]