Enhancement of gas-liquid mass transfer by small reactive particles at realistically high mass transfer coefficients:: absorption of sulfur dioxide into aqueous slurries of Ca(OH)2 and Mg(OH)2 particles

Chemical absorption of pure SO2 into aqueous slurries of fine and reactive Ca(OH)(2) and Mg(OH)(2) was studied in a stirred vessel at 298 K at realistically high mass transfer coefficients. The absorption process was theoretically analyzed using two different models. For the SO2-Ca(OH)(2) system, a single reaction plane model was used to estimate the theoretical enhancement factor and for the SO2-Mg(OH)(2) system, a two-reaction plane model incorporating the solids dissolution promoted by the reactions with the absorbed SO2 in the liquid film was employed. For the later system, the theoretical results could be more accurately predicted by a correct approach to estimate the enhancement caused due to suspended solids and the overall enhancement factor. The extra enhancement observed for the SO2-Mg(OH)(2) system could be explained from the reaction between SO2 and the dissolved [SO3](2-). (C) 2001 Elsevier Science B.V. All rights reserved.