백금족 금속과 규산염을 포함하는 모노리스형 자동차 폐촉매의 ICP - AES 분석을 위한 극초단파 분해 전처리 기법의 응용Application of Microwave Digestion Pretreatment Techniques for ICP - AES Analysis of Used Monolithic Automobile Catalysts Having Platinum Group - Metals and Silicates
Two different digestion procedures for the simultaneous determination of major and platinum-group element(PGE) in spent automobile catalysts containing PGE and silicates by inductively coupled plasma atomic emission spectrometry(ICP-AES) are compared. Combinations of mixed aids using HF, HNO3, HCl, HClO4, H2O2, and H3BO3 are utilized for the hot plate dissolution method and the closed-vessel microwave digestion method, The latter method has been shown to be relatively superior in terms of recovery, analysis time, and amount of aqua regia (3 parts HCl+ part HNO3 required to dissolve PGE in comparison with conventional open vessel hot-plate dissolution. The best results were drawn from the following conditions: In closed Teflon PFA vessels under microwave heating with temperature/pressure regulation, a 0.25 g portion of sample was digested in 2 mL of HF, 2 mL of HNO3 and 6 mL of HCl under the pressure of 200 psi(13.79 bar) at 180 ℃ for 1 hr, followed by a second digestion stage with 16 mL of 5 %(w/v) boric acid under the pressure of 20 psi(1.38 bar) at 100 ℃ for 10 min. After the microwave heating, the sample was post-treated with 10 mL of aqua regia twice by hot-plate heating. This condition gives the PGE recovery within 85-110 % and the relative standard deviations within 2 %. The method developed can therefore be regarded as an alternative method for routine analysis of spent automobile catalysts.