摘要
目的研究以液相沉淀法制备硅包膜钛白粉(SiO_(2)@TiO_(2))及氧化硅在TiO_(2)粒子表面的沉积成膜过程动力学,从而指导钛白粉表面改性工艺的优化。方法以硅酸钠为包膜剂在TiO_(2)表面包覆氧化硅膜层,通过比表面积、Zeta电位、SEM和酸溶率分析,研究包膜温度、包膜pH、熟化时间等工艺条件对SiO_(2)@TiO_(2)膜层结构的影响。采用动力学模型对氧化硅在TiO_(2)粒子表面的反应成膜过程进行计算拟合。结果在包膜温度368 K、包膜pH=9.0以及反应熟化时间180 min时,获得的SiO_(2)@TiO_(2)氧化硅膜层致密性好,酸溶率稳定在14%的较低水平,比表面积保持在10.58 m^(2)/g,等电点维持在2.34。氧化硅在TiO_(2)粒子表面的成核点形成阶段的活化能为16.31 kJ/mol,生长成膜阶段的活化能为25.80 kJ/mol。结论提高反应温度、在弱碱性条件下、延长熟化时间可使制备的SiO_(2)@TiO_(2)膜层致密性提高;SiO_(2)@TiO_(2)的比表面积、等电点与反映SiO_(2)@TiO_(2)膜层致密程度的酸溶率具有高度的相关性;氧化硅膜层在TiO_(2)表面的包覆过程分为成核点形成以及氧化硅沉积成膜两个阶段,均符合三级反应动力学特征。
In order to guide the optimization of the surface modification process of titanium dioxide,the work aims to study the preparation of silicon coated titanium dioxide(SiO_(2)@TiO_(2))by liquid phase precipitation method and the deposition kinetics of silicon oxide film on the surface of sulfuric acid method titanium dioxide particles.The surface of TiO_(2)was coated with a silicon oxide film with sodium silicate as the coating reagent.To characterize the structure of SiO_(2)@TiO_(2),the morphology of SiO_(2)@TiO_(2)particles was observed by scanning electron microscopy,the specific surface area was measured by a specific surface area analyzer,and the isoelectric point was detected by Zeta potential analyzer.During the experiment,a single variable method was used to study the effects of process parameters(coating temperature,coating pH and aging time)on the structure of titanium dioxide film.Under the optimal process conditions,the silicon oxide film forming process and reaction kinetic fitting analysis were conducted.The mass concentration of silicate ions at different reaction temperature was measured by XRF,the surface silicon content of TiO_(2)during the reaction was calculated,and the film forming process of silicon oxide was divided into two stages according to its concentration change trend.In the first stage,the heterogeneous nucleation of silicon oxide was produced by sodium silicate on the surface of titanium dioxide particles,forming nucleation points.In the second stage,silicon oxide molecules were deposited around the nucleation point to form a dense and uniform surface film layer.The reaction kinetics model was used to fit the two reaction stages.Firstly,the first-order to third-order reaction was used to fit the change trend of the silicate mass of TiO_(2)particles,then the reaction rate constant was calculated by the fitted kinetic model,and finally the activation energy of the reaction was calculated by the Arrhenius equation.The experimental results showed that the SiO_(2)@TiO_(2)prepared under the
作者
张成
周春勇
何俊
陈葵
ZHANG Cheng;ZHOU Chunyong;HE Jun;CHEN Kui(School of Chemical Engineering,East China University of Science and Technology,Shanghai 200237,China;Longbai Group Co.,Ltd.,Sichuan Deyang 618209,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2024年第8期210-219,共10页
Surface Technology
关键词
氧化硅
二氧化钛
膜层包覆
致密性
反应动力学
silicon oxide
titanium dioxide
film coating
compactness
reaction kinetics
