Determination of SO42- in cerium compounds by static ion exchange separation- barium sulfate turbidimetry
WANG Su-mei1,2,CUI Ai-duan1,2, HAO Qian1,2
1.National Engineering Research Centre of Rare Earth Metallurgy and Function Materials, Baotou 014030,China; 2.Baotou Research Institute of Rare Earths, Baotou 014030,China
Abstract：A method for determining sulfate radical in high cerium rare earth compound was established with static ion exchange separation - barium sulfate turbidimetry. A study was conducted on the effect of ion exchange separation conditions (R-SO3H resin dosage, extraction time, acidity) and turbidimetric conditions (analysis wavelength, acidity, amount of stabilizer, BaCl2 concentration, etc.) on test result. In 0.18 mol/L HCl, 15 g of strong acid type styrene cation exchange resins were mixed with test solution and its mixiture were kept for 1 h, then they were filtered by medium-speed filter paper. The result indicated that SO42- could be concentrated and separated from large amounts of substrate element cerium. In 2.4 mmol/L HCl and in the presence of some stabilizers and 20 g/L BaCl2 solution, SO42- and Ba2+ formed a stable colloidal suspension. At 430 nm, the absorbance of the solution increased linearly with the rise of the concentration of SO42-. The increased value A430 nm had excellent linear relationship with SO42- in the range of 0.80-6.00 μg/mL, with the linear correlation coefficient of 0.999 7 and lower detection limit of 0.010 %(mass fraction). The method was applied for determining SO42- in high cerium compounds and the results were consistent with those obtained by ICP-AES.
