利用小角度X射线散射测定八水氧氯化锆中锆结构

Zr(Ⅳ) structure in aqueous zirconium chloride octahydrate solution from small-angle X-ray scattering analysis

利用小角度X射线散射(SAXS)测量八水氧氯化锆溶液中锆的存在形式,结果表明锆在溶液中大部分是以多聚体形式存在,尤其是酸度极易对锆的聚合度产生影响。研究了八水氧氯化锆浓度、加热处理、放置时间及HCl浓度等因素对锆在溶液中存在形式的不同影响:以0.0~5.0 mol·L^(-1)HCl为溶剂,配制10~300 g·L^(-1)的氧氯化锆溶液,并考虑对溶液分别进行加热和长时间放置处理。对所配溶液进行了SAXS测试,利用Guinier方程计算了溶液中粒子的回转半径(Rg),同时利用求解最小封闭圆柱体问题的CYLview软件对溶液中锆的不同多聚体结构进行模拟计算,得到不同结构的理论Rg;通过比较Rg的实验值和计算值,确认不同条件锆液中锆粒子存在的主要形式。结果表明锆存在形式受酸度、浓度等多个因素的影响,尤其HCl的浓度是影响锆液中锆多聚体聚合度的关键;当不添加HCl时,低锆浓度溶液中锆的聚合度相对较高。

In this work,the dominant structures of Zr(Ⅳ) in zirconium oxychloride octahydrate solution were measured by using small‑angle X‑ray scattering(SAXS).The results show that the dominant structures of Zr(Ⅳ) are in the form of polymers in the solution,and the degrees of polymerization are susceptible to acidity.The different effects of the concentration,heating treatment,standing time,and HCl concentration of zirconium oxychloride in octahydrate were studied.With 0.0‑5.0 mol·L^(-1) HCl as the solvent,10‑300 g·L^(-1) zirconium oxychloride solution was prepared,moreover,the solution was heated and placed for a long time respectively.The SAXS tests were carried out for all the solutions,and the Rg experiments of the particles in the solution were calculated using the Guinier equation.Meanwhile,the CYLview program for solving the most minor enclosing cylinder problems was used to simulate the different polymer structures of Zr(Ⅳ) in zirconium oxychloride octahydrate solution and obtain the theoretical Rg values of different structures.By comparing the experimental Rg and the calculated Rg,the dominant structures of Zr(Ⅳ) in solution under different conditions were obtained.The results show that the dominant structures of Zr(Ⅳ) are affected by many factors such as acidity and concentration,especially the concentration of HCl is the key factor affecting the degree of polymerization.When the solvent is deionized water,the polymerization degree of zirconium is relatively high in solutions with low zirconium concentration.