钛铁合金中磷、铝的连续测定

Continuous Determination of Phosphorus and Aluminium in Titanium-iron Alloy

将钛铁样品经强氧化剂过氧化钠于高温熔融分解,使铁、钛等生成沉淀与磷、铝分离。分取部分滤液以酚酞为指示剂,用硝酸酸化,在0.81.2 mol/L硝酸介质中,加入钼酸铵溶液,使磷生成磷钼杂多酸,用正丁醇-三氯甲烷萃取,以氯化亚锡溶液将磷钼杂多酸还原为磷钼蓝,于波长680 nm处测量其吸光度。当分取的部分滤液用盐酸酸化时,加入过量乙二胺四乙酸二钠（EDTA）,调节pH值为5.86.2,用锌标准溶液滴定过量的EDTA,可以以氟化物将铝置换,释放出与铝相当量的EDTA。再用锌标准溶液滴定所取代出的EDTA,据此计算铝的含量。本方法具有稳定性较高、简便、快速、准确的特点。

The titanium-iron sample is melted and decomposed with strong oxidant,sodium peroxide,at a high temperature so that iron and titanium can be separated from phosphorus and aluminum in the form of deposition.Taking a part of the filtrate as the indicator by means of phenolphthalein,the solution with nitric acid in 0.8-1.2 mol/L can be adjusted by adding ammonium molybdate solution into the solution to produce phosphorus heteropoly acid.Extracted with butanol-chloroform,the phosphomolybdate acid can be reduced with stannous chloride solution to blue.Thus the absorbance of the solution can be measured at the wavelength of 680 nm.When a part of the filtrate are acidified with hydrochloric acid and added EDTA excessively.the data of pH can be adjusted to 5.86.2.After the excess EDTA are titrated with a zinc standard solution,the content of aluminum can be replaced with fluoride,so that the EDTA has a considerable amount of aluminum.If the EDTA will be titrated with the zinc standard solution again,therefore,the content of aluminum can be worked out according to the formula,.This is a simple,rapid and accurate method,provided with high stability.