超声波加速溶解-硝酸银比浊法测定海绵钛中氯

Determination of chlorine in sponge titanium by silver nitrate turbidmetry with ultrasonic accelerated dissolution

采用氢氟酸超声溶解样品,加入硝酸氧化低价钛,加入硼酸络合过量的氟离子,以丙三醇作为分散剂,利用超声的方式提高氯化银胶体的稳定性,以硝酸(1+19)定容,于420nm处进行测定,实现了硝酸银比浊法对海绵钛中氯的测定。实验表明:用20mL氢氟酸(1+5)于80kHz的超声波下震荡5min可消解1g左右的样品。分取适量体积的样品消解液,依次加入30mL硝酸(1+19)、2.5mL丙三醇和3.0mL硝酸银溶液,用硝酸(1+19)定容,超声波震荡40s,避光静置10min后测定,氯离子的质量浓度在0.05~2.4μg/mL范围内与其对应的吸光度呈线性关系,线性相关系数为0.999 7,方法中氯的检出限为0.05μg/mL。采用实验方法测定2个海绵钛样品中的氯,结果与国标方法 GB/T 4698.25—1996基本一致,相对标准偏差(RSD,n=11)小于5%,加标回收率在96%~103%之间。

The titanium sponge sample was dissolved with hydrofluoric acid by ultrasonic.The low-valence titanium was oxidized by adding nitric acid.The excessive fluorine ions were complexed with boric acid.The stability of silver chloride colloid was improved through ultrasonic with glycerol as dispersant.The solution was diluted with nitric acid（1＋19）and determined at 420 nm.Thus,a determination method of chlorine in titanium sponge by silver nitrate turbidimetry was established.The results indicated that about1 g of sample could be digested completely with 20 mL of hydrofluoric acid（1＋5）by ultrasonic at 80 kHz for 5min.30 mL of nitric acid（1＋19）,2.5mL of glycerol and 3.0mL of silver nitrate solution were added into certain volume of sample solution.After dilution to the mark with nitric acid（1＋19）,the solution was shaken up by ultrasonic for 40 s,kept in darkness for 10 min and followed by determination.The results indicated that the mass concentration of chlorine ions in range of 0.05-2.4μg/mL showed linear relationship with its corresponding absorbance.The linear correlation coefficient was 0.999 7.The detection limit of chlorine was 0.05μg/mL.The content of chlorine in two titanium sponge samples was determined according to the experimental method.The results were basically consistent with those obtained by national standard method GB/T 4698.25-1996.The relative standard deviation（RSD,n=11）was less than 5%.The recoveries were between 96% and 103%.