Catalytic kinetic spectrophotometry determination of trace Rhodium with Rh(III)-KIO_4-AzureII system

Under the condition of 100 ℃ and hydrochloric acid as medium,the depigmentation reaction of potassium periodate oxidizing AzureⅡcan be greatly catalyzed by rhodium(III).A new catalytic kinetic analyzing method was established based on that.The optimal experimental condition of the reaction was discussed.The absorbency difference △A remained good linear relationship with the mass concentration of rhodium(III)in the range of 0.004-0.060 μg·mL-1,and the detection limit was 1.09×10-10 g·mL.The relative standard deviation RSD was 1.15%(n=13).The dynamic parameter was also determined and the reaction a first order reaction to rhodium(III) and the total reaction was pseudo first order reaction.The apparent rate constant was 1.09×10-3s-1,and the apparent activation energy was 76.07 kJ·mol-1.It was applied to the determination of rhodium(III) in sample molecular sieve and active carbon with the recovery rate between 103.6-105.2 % that met the request of trace analysis.