Abstract: I- in the kelp soaking liquid was oxidized into IO3- by the mixed oxidant NaNO2-H2O2，and with the oxidant IO3- ，I-in the soaking liquid was further oxidized into elemental iodine，to achieve the purpose of recycling iodine. The reaction conditions of using mixed oxidant to prepare IO3-  were studied.The optimum reaction conditions were as follows: the dosage of mixed oxidant was 50 μL，8%（mass fraction） NaNO2 solution and 150 μL，30%（mass fraction） H2O2 （the amount-of-sub- stance ratio of H2O2 to I- is approximately 3.5∶1)，in 100 mL of kelp soaking liquid with the iodine content of 498 mg/kg.The obtained IO3- was as the oxidant to oxidize I-.The effects of pH，amount-of-substance ratio of I- to IO3-  and reaction time on I- conversation rate were investigated.Results showed that when the pH was 2.0，the amount-of-substance ratio of I- to IO3-  was 5∶1，and the reaction time was for 30 min，the iodine oxidation rate was 94.96%.

Key words: iodine, hydrogen peroxide, sodium nitrite, oxidation reaction, iodine extraction from kelp