Influence of NO2 and metal ions on oxidation of aqueous-phase S(IV) in atmospheric concentrations

Anais da Academia Brasileira de Ciências

Cláudia R. Martins¹  Janete J.f. Alves¹  Wanessa B.d. Carvalho¹  Cristiane S.c. Cardoso¹  Jailson B. De Andrade¹ 

[1] ,Universidade Federal da Bahia Instituto de Química Salvador BA ,Brasil

关键词: aqueous S(IV) oxidation;    metal ions;    NO2;    acid rain formation;    oxidação de S(IV);    íons metálicos;    NO2;    formação de chuva ácida;   

DOI  :  10.1590/S0001-37652008000200006

来源: SciELO

【 摘 要 】

An investigation was made of the influence of atmospheric concentrations (15 or 130 ppbv) of NO2 on the aqueous-phase oxidation rate of S(IV) in the presence and absence of Fe(III), Mn(II) and Cr(VI) metal ions under controlled experimental conditions (pH, T, concentration of reactants, etc.). The reaction rate in the presence of the NO2 flow was slower than the reaction rate using only clean air with an initial S(IV) concentration of 10-4 mol/L. NO2 appears to react with S(IV), producing a kind of inhibitor that slows down the reaction. Conversely, tenfold lower concentrations of S(IV) ([S(IV)]º = 10-5 mol/L) caused a faster reaction in the presence of NO2 than the reaction using purified air. Under these conditions, therefore, the equilibrium shifts to sulfate formation. With the addition of Fe(III), Mn(II) or Cr(VI) in the presence of a NO2 flow, the reaction occurred faster under all the conditions in which S(IV) oxidation was investigated.

【 授权许可】

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