超声溶解电位滴定法测定海绵钛中氯

Determination of chlorine in sponge titanium by potentiometric titration with ultrasonic dissolution

使用超声震荡辅助氢氟酸、硝酸溶解海绵钛试样,加入硼酸生成氟硼酸掩蔽氢氟酸,用硝酸银溶液进行电位滴定,测定了海绵钛中微量氯。由于采用快速的等间隔滴定和在滴定完成后40 s记录电位值,因此减少残余电位漂移对测定的影响。滴定终点采用电位二阶导数为零的精确方法判断,测定误差小,结果更可靠。试验表明,基体钛对氯的测定设有干扰,试样中S2-,Br-,I-,CN-对测定有干扰,但存在量很低,影响可以忽略。用本法测定2个海绵钛样中氯,结果与国家标准方法(硫化银分光光度法)相符,相对标准偏差分别为1.48%和2.59%(n=8)。

Ultrasonic concussion was used to assist hydrofluoric acid and nitric acid in dissolving sponge titanium sample,and boric acid was added to generate fluoboric acid which made hydrofluoric acid masked. The determination of micro-titanium in sponge titanium was performed by potentiometric titration with silver nitrate solution. For quick equal interval titration and reading potential value at forty seconds after titration, the influence of residual potential drift on determination was reduced. The potential second derivative with zero as end-point was applied for the judgement of end-point, with low inaccuracy and more reliable results. The test results indicated that matrix titanium did not interfere in the determination of chlorine, but S^2- ,Br^- ,I^- and CN in the sample did. However,the influence of S^2- ,Br^- ,I^- and CN- could be ignored because of their low contents. The proposed method has been applied to the determination of chlorine in two sponge titanium samples. The results are consistent with those of national standard method （silver sulfide spectrophotometry） and the RSD are 1. 48% and 2.59% respectively （n=8）.