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A decomposition apparatus was established consisting of a reaction tube and a long air-cooling conden-ser for the separation of antimony and bismuth through volatilization. It is demonstrated that the reactionSb_2O_3+6NH_4I=2SbI_3+6NH_3+3H_2O starts at 300℃ and completes at 380℃ in 8 min. In comparison,the reaction Bi_2O_3+6NH_4I=2BiI_3+6NH_8+3H_2O will not take place below 450℃ and will complete at550℃. The differences in volatilizing temperature between antimony and bismuth iodide are large enough tomake them separate at different temperatures. Experimental data show that antimony iodide was sublimatedat 380℃ without any loss of bismuth, and upon the completion of SbI_8 volatilzation the Iong condenser tubecan be substituted for by a clean one to collect volatilizing bismuth iodide at the temperature of 550℃.Results are in good agreement with those obtained from thermodifferential-thermogravimetric analyses. Determination of antimony was done using extraction spectrophotometric method with the reagent 5-Br-PADAP, and that of bismuth using spectrophotometric method with Xylenol Orange. The method isshople, rapid, accurate and suitable for rock and other geological samples containing antimony and bismuthin the range of X--X 10~2 ppm.
It is demonstrated that the reactionSb_2O_3 + 6NH_4I = 2SbI_3 + 6NH_3 + 3H_2O starts at 300 ℃ and completes at 380 ° C in 8 min. In the reaction Bi_2O_3 + 6NH_4I = 2BiI_3 + 6NH_8 + 3H_2O will not take place below 450 ° C and will complete at 550 ° C. The differences in volatilizing temperature between antimony and bismuth iodide are large enough tomake them separate at different temperatures. Experimental data show that antimony iodide was sublimatedat 380 ° C without any loss of bismuth, and upon the completion of SbI_8 volatilzation the Iong condenser tubecan be substituted for by a clean one to collect volatilizing bismuth iodide at the temperature of 550 ° C. Results are in good agreement with these obtained from thermodifferential-thermogravimetric analyzes. Determination of antimony was done using extraction spectrophoto metric method with the reagent 5-Br-PADAP, and that of bismuth using spectrophotometric method with Xylenol Orange. The method is shople, rapid, accurate and suitable for rock and other geological samples containing antimony and bismuth in the range of X- 2 ppm.