铋磷钼蓝分光光度法测定钛白粉中磷

钛白粉中大量存在的钛在分解时易水解形成较细的沉淀,即使反复过滤,滤液中都残留有少量细小沉淀颗粒,故而会影响光度法对磷的测定。针对这一问题,实验采用无水碳酸钠和硼酸混合熔剂熔融钛白粉试样,再加入硫酸中低温溶解熔融样,然后在硫酸介质中,加入高锰酸钾将磷氧化为正磷酸根的形式存在于溶液中,加入氢氧化钠与基体钛反应生成三钛酸钠沉淀,过滤,实现了钛与磷的分离,从而建立了铋磷钼蓝光度法测定钛白粉中磷的测定方法。在优化的实验条件下,磷质量浓度在0.009～0.382 μg/mL范围内与其吸光度符合比尔定律,校准曲线的相关系数为0.999 9。采用实验方法对钛白粉样品进行8次平行测定,结果的相对标准偏差(RSD,n=8)小于4.0%,回收率在98%～103%之间。采用微波消解-电感耦合等离子体质谱法(ICP-MS)进行方法对照试验,结果表明两种方法的测定结果基本一致。

Determination of phosphorus in titanium dioxide by phosphomolybdate bismuth blue spectrophotometry

Much titanium is easily hydrolyzed during the decomposition of titanium dioxide to form fine precipitates. Even through filtration over and over again, a few fine precipitate particles are still residual in filtrate, which will influence the determination of phosphorus by spectrophotometry. In order to solve this problem, the titanium dioxide sample was fused with mixed flux of anhydrous sodium carbonate and boric acid, and the melted sample was dissolved with sulfuric acid medium at low temperature. In sulfuric acid medium, phosphorus was oxidized to orthophosphate for existing in solution by potassium permanganate, and sodium hydroxide was then added to react with matrix titanium to form sodium trititanate precipitate, realizing the separation of phosphorus with titanium by filtration. Consequently, a determination method of phosphorus in titanium dioxide was established by phosphomolybdate bismuth blue spectrophotometry. Under the optimized experimental conditions, the mass concentration of phosphorus in range of 0.009-0.382 μg/mL and the corresponding absorbance obeyed to Beer’s law. The correlation coefficient of calibration curve was 0.999 9. The titanium dioxide sample was determined parallelly according to the experimental method for eight times. The relative standard deviation(RSD, n=8) was less than 4.0%. The recoveries were between 98% and 103%. The comparison tested was conducted with microwave digestion-inductively coupled plasma mass spectrometry (ICP-MS). The results indicated that the results of the two methods were basically consistent.