Adsorption equilibrium and breakthrough analysis for sulfur dioxide adsorption on silica gel

Abstract

In this work, the adsorption equilibrium and adsorption rate of sulfur dioxide were investigated on silica gel. A packed bed adsorber 0.1 m in length and 0.0095 m in diameter was used for the adsorption experiments. The adsorption equilibrium experiments were carried out at 473 K constant temperature with an initial sulfur dioxide concentration in the range 430–3400 p.p.m. in nitrogen carrier gas. The experimental adsorption isotherms were compared with the Freundlich, Langmuir, and the linearized form of the Brunauer–Emmett–Teller and the Dubinin–Radushkevitch–Kaganer models by the nonlinear least-squares estimate method. The Freundlich model gave the best fit with a correlation coefficient greater than 0.98, suggesting a surface adsorption mechanism for sulfur dioxide adsorption on silica gel. The deactivation model was applied to the adsorption rate data. It was found that the adsorption rate data fitted well with the deactivation model. Observed adsorption rate constants and the first-order deactivation rate constants were obtained from the model. The nonlinear least-squares analysis technique was used to estimate the parameters appearing in the deactivation model. The breakthrough experiments were repeated at 1610 p.p.m. constant initial sulfur dioxide concentration in a temperature range of 323–473 K, and the effect of initial sulfur dioxide concentration and the effect of temperature were investigated on the model results.