Numerical Simulation of Gamma-valerolactone Adsorption Into Porous Spheres in a Batch Process

Abstract

The production of ethanol from lignocellulosic biomass is more complex in relation to ethanol produced from feedstock containing sugars or starch, since it requires the conversion of polysaccharides, cellulose or hemicellulose, into fermentable sugars. An alternative to improve this conversion of biomass polysaccharides into sugars is the use of ?-valerolactone (GVL) as a solvent. However, the GVL must be removed before the fermentation, since its presence is harmful to the microorganisms that metabolize glucose to produce ethanol. One extraction technique is the use of subcritical CO2, which is able to separate large amounts of GVL, but a complementary method is still required to separate small quantities of GVL remaining in the sugar solution, which can be done efficiently with adsorption. In this work, the adsorption of ?-valerolactone by porous spheres made of a resin in batch mode is studied to remove the GVL from the sugar solution containing glucose. This work is computational and the modelling considers the mass transfer from the solution to the surface of the spheres, the diffusion inside the pores of the spheres, and then the adsorption of GVL. The numerical resolution is done using two numerical methods, the finite differences and the variational method. The results are compared using different numbers of radial intervals in the spherical particles.