Chlorine Absorption in Sulfite Solutions

ABSTRACT

The rate of chlorine (5 to 300 ppm Cl₂) absorption into aqueous sulfite/bisulfite (0 to 10 mM S(IV)) was measured using a stirred-cell reactor and a wetted-wall column at pH 4.7 and 5.7. Chlorine absorption was modeled using the theory of mass transfer with fast reaction. Chlorine reacts quickly with S(IV) to form chloride and sulfate near the gas/liquid interface. The rate constant for the reaction of chlorine with S(IV) at 25°C was determined to be 1.1 × 10⁹ L/mol-s. The enhancement of the succinate buffer on the chlorine hydrolysis rate was quantified. The addition of sodium chloride (NaCl) did not affect the rate of Cl₂ absorption in S(IV). Oxygen did not affect the rate of chlorine absorption or catalyze S(IV) oxidation. These results are relevant in the simultaneous removal of chlorine, sulfur dioxide, and elemental mercury from flue gas and may also be applicable to scrubber design for removal of chlorine in the pulp and paper and other industries.

Key Words::

• Chlorine
• Sulfite
• Adsorption
• Mass transfer
• Reaction