腐蚀液回收制取纳米二氧化钛转变过程

Recovery from wastewater and processes involved in preparation of nanoscale TiO_2

本文采用投加氨水沉淀法,利用含硫酸钛的废液制备出纳米二氧化钛。涉及的反应过程包括:硫酸钛与水的反应生成硫酸氧钛;硫酸氧钛水解形成偏钛酸;偏钛酸的热处理和脱水产生二氧化钛。二氧化钛的进一步热处理转变过程包括:非晶态二氧化钛的晶化转变;锐钛矿向金红石的高温相变。所制备的二氧化钛在350℃至700℃热处理可以获得单相锐钛矿相。锐钛矿颗粒尺度从350℃的9 nm增长到700℃的68 nm左右。在700～800℃之间处理,可获得锐钛矿相和金红石相双相组织。金红石颗粒尺度从800℃的83 nm增长到900℃的109 nm左右。900℃以上温度热处理可以获得单相金红石相。

Using titanium sulfate containing wastewater as the raw material, and by homogeneous precipitation method, nanosized TiO2 was prepared in this paper. The involved reaction processes are as follows. The titanium sulfate reacts with water to produce titanium oxysulfate. The later changes to metatitanic acid by thermal hydrolysis. Heat treat treating and dehydrolyzing make metatitanic acid to transform titanium dioxide. There are still some transformations after further heat treatments. The amorphous titanium dioxide transforms to crystalline anatase. The phase transformation from anatase to futile takes place at higher temperature. Mono-phase anatase could be obtained after heat treating between 350℃ and 700℃. The grain size of anatase increases from 9 nm to 68 nm. Dual-phase structure ofanatase and futile are exists between 700℃ and 800℃. The grain size of futile increases from 83 nm to 109 nm from 800℃ to 900℃. Mono-phase futile could be obtained after heat treating higher than 900℃.