Mg^(2+)//CO_3^(2-)、HCO_3^-、OH^--H_2O体系相平衡研究  

On phase equilibrium of Mg^(2+)//CO_3^(2-),HCO_3^-,OH^--H_2O system

作　　者：赵颖颖 史婧祎[1] 李丹 吴梦凡 谢英惠 袁俊生 ZHAO Yingying;SHI Jingyi;LI Dan;WU Mengfan;XIE Yinghui;YUAN Junsheng(School of Marine Science and Engineering, Hebei University of Technology, Tianjin 300130, China;Engineering Research Center of Seawater Utilization Technology, Ministry of Education, Tianjin 300130, China;Modern Marine Chemical Collaborative Innovation Center in Hebei Province, Tianjin 300130, China)

机构地区：[1]河北工业大学海洋科学与工程学院,天津300130 [2]海水资源高效利用化工技术教育部工程研究中心,天津300130 [3]河北省现代海洋化工协同创新中心,天津300130

出　　处：《河北工业大学学报》2018年第1期53-58,共6页Journal of Hebei University of Technology

基　　金：国家自然科学基金(21306037);国家科技支撑计划(2015BAB09B00);天津市自然科学基金(13JCQNJC05600,14JCYBJC20700);河北省高层次人才资助项目(C2013003041);河北省科技计划项目(14273105D,16273602D,17273101D);中国博士后科学基金(2017M611142)

摘　　要：新型碱源脱钙固碳之后的海水中存在的大量镁离子和碳酸氢根,提取其中的镁离子可以实现海水镁资源利用并将海水进一步软化;分离碳酸氢根使固碳彻底,有利于后续海水资源利用.镁和碳酸氢根的提取需要在碱性条件下进行,因此,本实验将CO_2脱钙之后的海水体系简化为Mg^(2+)//CO_3^(2-)、HCO_3-、OH^--H_2O体系.并利用等温溶解平衡法,研究该体系在10℃条件下的相平衡,探索体系的析盐规律.液相组成通过溶液滴定法获得,由X射线衍射分析技术测出固相物质组成得出,并利用origin9.0软件绘制出四元体系相图.相图中得到1个三相共饱点,固相物组成是MgCO_3·3H_2O、Mg(OH)_2和Mg_5(CO_3)4(OH)_2·8H_2O;3条共饱和曲线分别为MgCO_3·3H_2O、Mg(OH)_2的共饱线,Mg_5(CO_3)4(OH)_2·8H_2O、Mg(OH)_2的共饱线,Mg_5(CO_3)4(OH)_2·8H_2O、MgCO_3·3H_2O的共饱线;2个明显的结晶区,MgCO_3·3H_2O结晶区和Mg(OH)_2结晶区,1个Mg_5(CO_3)4(OH)_2·8H_2O的部分结晶区.以上实验数据可为盐化工生产及结晶分离提纯提供参考依据.A large number of magnesium ions and bicarbonate radical in the seawater after decalcification and carbon fixation of the new alkaline source.The extraction of magnesium ions can realize the utilization of seawater magnesium resources and further soften seawater.Meanwhile separation of bicarbonate is conducive to the subsequent use of seawater resources.The extraction of magnesium and bicarbonate need to be carried out under alkaline condition.Therefore,in this experiment,the seawater system after CO2decalcification is simplifi ed as Mg2+//CO2-3,HCO-3,OH--H2O system.In order to explore the law of salt deposition in explosive system,the isothermal dissolution equilibrium method is used to study the phase equilibrium of the seawater system which is the phase equilibrium system at10℃.The liquid phase composition is obtained with solution titration method,the composition of the solid phase material is determined by X-ray diffraction analysis technology,and the phase diagram of the quaternary system is drawn by using the software of origin9.0.We obtain a three-phasetotal saturation which comprises MgCO3·3H2O,Mg(O H)2and Mg5(CO3)4(OH)2·8H2O.The three co-saturated curves are respectively as follows:MgCO3.·3H2O and Mg(OH)2co-saturated line,Mg5(CO3)4(OH)2·8H2O and Mg(OH)2co-saturated line,Mg5(CO3)4(O H)2·8H2O and MgCO3·3H2O co-saturated line;the two distinct crystalline regions are MgC〇3·3H2O crystalline region and Mg(OH)2crystalline region;a partial crystalline region of Mg5(CO3)4(OH)2·8H2O.The experiment provides a reference for salt chemical production and crystallization separation and purification.

关 键 词：平衡 热力学 四元体系 水盐体系 溶解度 

分 类 号：O642.42[理学—物理化学]