二安替比林甲烷光度法测定含钛冶金物料中二氧化钛

应经济、环保要求,结合含钛冶金物料酸溶解困难的特点,实验采用硼酸-无水碳酸钠熔剂代替传统氧化剂焦硫酸钾和过氧化钠进行试样前处理。因硫酸高铁铵滴定法不适用于批量试样的检测,传统分光光度计因吸光度最佳范围0.2～0.8,高含量二氧化钛含量的测定需多次分取或分取小体积显色,这样将引入较大分取体积分量的不确定度,导致结果再现性差。实验充分利用现代紫外分光光度计高量程、线性宽的特点,通过依次优化称样量、定容体积、分取体积、显色体积、波长、比色皿厚度等参数,控制分析误差在合理的范围内,从而实现一次性大体积分取显色,利用二安替比林甲烷分光光度法测定含钛冶金物料中5.0%～70.0%的二氧化钛含量。每100 mL显色液中二氧化钛在100～1 500 μg,其吸光度在0.1～2.5范围内符合比尔定律。波长420 nm,表观摩尔吸光系数为1.24×10⁴ L·mol^-1·cm^-1,回归曲线方程为A=1.568 4 m+0.014 1,线性相关系数为0.999 95。样品测定结果与认定值、硫酸高铁铵滴定法的测定值相吻合,相对标准偏差(RSD,n=8)为0.14%～0.44％,方法的精密度不逊色于现有行业标准,具有推广价值。

Determination of titanium dioxide in titanium-containing metallurgical materials by diantipyrylmethane spectrophotometry

According to the requirements of economy and environmental protection, the anhydrous sodium carbonate-boric acid flux was used to replace the traditional oxidizing agents (potassium pyrosulfate and sodium peroxide) for the pretreatment of titanium-containing metallurgical materials which was hardly dissolved. The ammonium ferric sulfate titration method was not suitable for the detection of batches of samples. The optimal absorbance range of traditional spectrophotometer was 0.2-0.8.For the determination of high content titanium dioxide, several times of sub-sampling or sampling with small volume were required. This would introduce the large uncertainty of volume component, leading to the low repeatability of results.The characteristics of modern ultraviolet spectrophotometer, including high range and wide linearity, were fully utilized. The parameters such as sample mass, dilution volume, sampling volume, coloring volume, wavelength and cuvette thickness were optimized. The analysis error was controlled within the reasonable range. Therefore, the coloring with large volume in one time was realized. The content of titanium dioxide (5.0%-70.0%) in titanium-containing metallurgical materials was determined by diantipyrylmethane spectrophotometry. When the content of titanium dioxide in 100 mL of coloring solution was 100-1 500 μg, the Beer’s law was obeyed for the absorbance in range of 0.1-2.5. The apparent molar absorptivity was 1.24×10⁴ L·mol^-1·cm^-1 at wavelength of 420 nm. The regression curve equation was A=1.568 4 m+0.014 1 with linear correlation coefficient of 0.999 95. The determination results of sample were consistent with the certified values and those obtained by ammonium ferric sulfate titration method. The relative standard deviations (RSD, n=8) were between 0.14% and 0.44%. The precision of the proposed method was not inferior to the current industrial standards. The proposed method had popularization value.