CHEMISORPTION OF SULFUR (IV) OXIDE BY WATER UNDER STATIC CONDITIONS. HENRY’S CONSTANT

Abstract

The absorption of sulfur (IV) oxide by water and aqueous solutions has the practical relevance as well as the theoretical interest. The mathematical model showing the relationship of effective Henry’s constant (HS(IV)*, М/Pa) with Henry’s constant (HSO2, М/Pа), and mole fractions of SO2-H2O, HSO3-, S2O5 (2-) and SO32- is: where K1and K2– dissociation constants of “sulphurous acid” for the first and second degrees, respectively; K*– dimerization constant of hydrogensulfite ions; [H+] – hydrogen ions molar concentration, M.For the detailed study of a heterogeneous equilibrium in the SO2– H2O system and checking of the equation above written the chemisorption of sulfur(IV) oxide water un-der static conditions at 298 K has been investigated. The sorption isotherm of sulfur oxide (IV) water at pSO2= 3,325 ÷26,6 kPa has been obtained.The diagram of the component composition of the SO2– H2O equilibrium depending on the total SO2 content (QSO2≤ 0,122 M; 1,10 ≤ pH ≤ 1,75). The concentration dependings (HS(IV)*) in the SO2– H2O system have been obtained. According to our data pyrosulfite ions relative content is more in the order of hydrosulfite ions content. The estimation on the contribution HSO3- and - S2O5 (2-) to HS(IV)*has been done. The dependencies HSO2, K1and K*on the ionic strength of the solution have been obtained. The numerical value of the thermodynamic Henry’s constant has been determined.The dependencies identified in this paper are planned to use in assessing of the efficiency of SO2– H2O solution binding by of N,O-containing organic bases and thus describing of the observed heterogeneous equilibrium.

Keywords

• оксид сірки (IV), водні розчини, іонно-молекулярний склад, константа Генрі