Determination of chlorine in rare earth carbonate by chloride ion selective electrode with standard addition method
ZHANG Ji-kai1,2, CHEN Dong-ying*1, QIU Xiao-ying2, HONG Kan1, LI Zhong-qi1
1.Ganzhou Nonferrous Metallurgy Research Institute,Ganzhou 341000,China; 2.Jiangxi Ionic Rare Earth Engineering Research Company Limited,Ganzhou 341000,China
Abstract：The sample was dissolved with HNO3(1+2). The chlorine in sample totally existed in solution in form of Cl-. The content of chlorine in rare earth carbonate could be calculated by measuring the mass concentration of Cl- in solution. With potassium nitrate and trisodium citrate as total ionic strength adjustment buffer solution (TISAB), the rare earth ions were mainly complexed by EDTA. The content of chlorine in rare earth carbonate was determined by chloride ion selective electrode with standard addition method. The results showed that the negative logarithm of mass concentration of Cl- in solution was linear to its corresponding electrode potential (E) under the following conditions: the mass concentration of Cl- in solution was in range of 2.0-40.0 mg/L; the dosage of EDTA solution and TISAB solution was 10 mL, respectively. The linear correlation coefficient was r=0.999 9. In order to guarantee the accuracy of determination results, the determination of sample and electrode response slope (S value) must be conducted in a same constant temperature system. The detection limit was 0.947 mg/L. The determination of Cl- (5 mg/L) was not interfered by much K+, Na+ and NO-3. The maximum tolerant amount for RE3+, Ca2+, Fe2+ and Na+ was 10.0, 4.0, 5.5 and 23 g/L, respectively. The content of chlorine in lanthanum carbonate and mixed rare earth carbonate samples was determined according to the experimental method. The relative standard deviations (RSD, n=5) were less than 5%. The results were consistent with those obtained by silver chloride turbidimetry.
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ZHANG Ji-kai, CHEN Dong-ying, QIU Xiao-ying, HONG Kan, LI Zhong-qi. Determination of chlorine in rare earth carbonate by chloride ion selective electrode with standard addition method. , 2017, 37(4): 22-26.
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