Absorption of chlorine in aqueous solutions of phenols and aromatic sulfonic acids

Abstract

The kinetics of absorption of Cl₂ in aqueous solutions of phenol, o-chlorpophenol, p-chlorpophenol, ρ-nitrophenol, ℳ -aminophenol-hydrochloride, ρtoluenesulfonic acid and ℳ -nitrobenzenesulfonic acid, at 30°C, was studied in a model stirred contactor, with a plane liquid interface and independent stirrers for gas and liquid phases. A laminar jet apparatus was also used to study the kinetics of chlorination of aqueous ρ-toluenesulfonic acid and ℳ -aminophenol-hydrochloride. All the reactions were found to be first order in Cl₂ and first order in the dissolved organic substance. The values of second order rate constants at 30°C varied from about 1.1 × 10⁶ to 5.7 × 10⁹ cm³/g mole sec for phenolic substances and from 1.1 × 10⁶ to 3.5 × 10⁶, cm³/g mole sec for the sulfonic acids. Chlorination of ο- and ρ-chlorophenol in aqueous buffered solutions was analysed on the basis of absorption of Cl₂ followed by two parallel fast pseudo-first order reactions, where the hydrolysis of Cl₂, catalysed by buffer anion, and the chlorination of chlorophenol were found to occur in the liquid film. Measurements of the effective interfacial area and the liquid-side mass transfer coefficient were made in a mechanically agitated contactor and a bubble column by using some of these chlorination reactions.