液相除杂制备高纯硅酸钠溶液机理  

Mechanism for Preparation of High Purity Sodium Silicate Solution by Impurity Removal in Liquid Phase

作　　者：夏毅 吕慧[1] 曹贵平[1] XIA Yi;LYU Hui;CAO Guiping(State Key Laboratory of Chemical Engineering,East China University of Science and Technology,Shanghai 200237,China)

机构地区：[1]华东理工大学化学工程联合国家重点实验室,上海200237

出　　处：《华东理工大学学报(自然科学版)》2025年第1期23-34,共12页Journal of East China University of Science and Technology

摘　　要：硅酸钠溶液的纯度是影响液相法制备高纯二氧化硅的重要因素。本文提出以Ca^(2+)作为硅酸钠溶液除杂剂,系统地研究除杂剂种类、反应时间、反应温度和nCa∶nSi对除杂效果的影响。硅酸钠溶液中按nCa∶nSi为1∶20添加CaCl2试剂,在180℃下反应16 h,溶液中金属元素铝、铁和钛杂质脱除率达到95%。分析除杂反应所得固体的晶体结构及表面形貌表明,在反应中Ca^(2+)将溶液中的杂质离子以Ca-Si沉淀物的形式脱除;结合元素分析结果证明杂质离子成功结合到Ca-Si沉淀物中。通过分子模拟探究除杂反应的路径,模拟结果表明Ca-Si沉淀由Ca^(2+)和Si-O四面体形成的硅酸根结合而生成,其中部分Si-O四面体中的硅被铝、铁、钛等金属杂质离子取代,形成含金属杂质的钙沉淀物,因此沉淀中出现了铝、铁、钛等元素,钠和钾等离子因电荷吸引而进入沉淀中,形成各类硅酸盐沉淀。The purity of sodium silicate solution is an important factor affecting the preparation of high purity silica by liquid phase method.The effects of Ca^(2+)on the impurity removal of sodium silicate solution,reaction time,reaction temperature and Ca-Si molar ratio were studied systematically.The removal rate of Al,Fe and Ti impurities in sodium silicate solution reached 95%after the reaction at 180℃for 16 h with the addition of CaCl2 at Ca-Si molar ratio of 1∶20.The crystal structure and surface morphology of the solids obtained from the impurity removal reaction were analyzed,which showed that impurity ions in the solution were removed by Ca^(2+)in the form of Ca-Si precipitate.Combined with the analysis results of the distribution of elements and the mass proportion of elements,it was proved that impurity ions were successfully combined into Ca-Si precipitate.Molecular simulation was used to explore the path of impurity removal reaction.The simulation results showed that Ca-Si precipitation was formed by the combination of Ca^(2+)and silicate formed by Si-O tetrahedron,in which Si in some Si-O tetrahedron was replaced by Al,Fe,Ti and other metal impurity ions,forming Ca precipitates containing metal impurities.Therefore,Al,Fe,Ti and other elements appear in the precipitation,and ions such as Na and K enter the precipitation due to charge attraction,forming various silicate precipitates.With the change of crystal cell volume as the criterion for the formation of impurity ions,the increase of lattice energy proves that the impurity removal reaction generates stable precipitation,which provides theoretical guidance for the mechanism of Ca^(2+)formation of silicate precipitation and absorption of impurities in sodium silicate solution.

关 键 词：硅酸钠溶液 纯化 条件优化 沉淀 分子模拟 

分 类 号：TQ115[化学工程—无机化工]