Hydrothermal synthesis of high purity TiO2 from metatitanic acid via short sulfate process
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摘要: 以低浓度工业钛液经钛白短流程工艺水解所制的偏钛酸为原料,经水热工艺制备出高纯二氧化钛,考察了浆料浓度、水热温度、水热时间等对产物结构与纯度的影响,采用XRD、粒度分析、BET、SEM和TiO2含量测定等对样品进行了表征。认为:水热条件影响水热偏钛酸的溶解、成核、晶体生长、聚合与团聚等,并影响偏钛酸的结构、粒径分布和比表面积,改变其杂质吸附量,并最终影响高纯TiO2的结构与纯度。最佳水热条件为:料浆浓度160 g/L,水热温度140 ℃,水热时间36 h,所得高纯二氧化钛含量为99.99%。Abstract: High purity titanium dioxide was prepared through the hydrothermal synthesis route, using metatitanic acid as precursor which was hydrolyzed from low concentration industrial titanyl sulfate solution via short sulfate process. The effects of slurry mass concentration, hydrothermal temperature and hydrothermal time on the structure and purity of the products were investigated. The samples were characterized by XRD, particle size distribution, BET analysis, SEM and TiO2 content determination. The hydrothermal conditions, e.g. slurry mass concentration, hydrothermal temperature and hydrothermal time influence the dissolution, nucleation, crystal growth, polymerization and agglomeration of the precipitates, and the structure, particle size distribution and specific surface area of the hydrothermal metatitanic acid are also affected, which leads to the content variation of the adsorbed impurities and ultimately influences the structure and purity of TiO2. The optimized hydrothermal conditions are the slurry concentration of 160 g/L, hydrothermal temperature of 140 ℃ for 36 h, with the high purity TiO2 (99.99%) obtained.
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表 1 浆料浓度对偏钛酸结构和高纯二氧化钛的结构与含量影响
Table 1. Effect of slurry concentration on structure and TiO2 content of metatitanic acid and high purity TiO2
MA 浆料浓度/(g·L−1) L(101),MA/nm DAV,MA /µm SBET/(m2·g−1) TiO2 DAV,TiO2 /µm L(110)/nm w(TiO2)/% 80 8.8 0.84 116.1 A1 0.25 112 99.87 B 120 8.4 0.78 102.8 B1 0.23 101 99.95 C 160 8.2 0.71 96.93 C1 0.21 98.2 99.97 D 200 8.3 0.80 100.2 D1 0.24 101 99.93 E 240 8.6 0.85 108.4 E1 0.26 109 99.85 表 2 水热温度对偏钛酸和二氧化钛的影响
Table 2. Effect of hydrothermal temperature on the structures and composition of metatitanic acid and TiO2
MA 水热温度/℃ SBET/(m2·g−1) DAV,PTS /µm TiO2 DAV,TiO2 /µm w(TiO2)/% F 105 125.1 0.84 F1 0.37 99.25 G 120 107.2 0.79 G1 0.30 99.76 H 140 96.93 0.71 H1 0.21 99.97 I 160 100.7 0.78 I1 0.26 99.81 J 180 113.9 0.83 J1 0.33 99.28 表 3 水热时间对偏钛酸和高纯二氧化的影响
Table 3. Effect of hydrothermal time on the structure and composition for metatitanic acid and TiO2
MA 水热时间/h SBET /(m2·g−1) DAV,PTS /µm TiO2 DAV,TiO2 /µm w(TiO2)/% K 12 107.4 0.79 K1 0.28 99.83 L 24 96.93 0.71 L1 0.21 99.97 M 36 91.58 0.69 M1 0.20 99.99 N 48 104.5 0.76 N1 0.24 99.95 Q 60 111.8 0.81 Q1 0.30 99.85 -
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