Experiments were conducted to investigate the influence of superficial gas velocity and fluid properties on the volumetric mass transfer coefficient in Newtonian and non-Newtonian systems in the riser and down comer of an external loop airlift reactor. Aqueous solutions of carboxy methyl cellulose, CMC was used as the non-Newtonian fluid. The k_L a increased with increase in U_sg and of alcohol concentrations and a decreasing trend was observed with increase in concentration ofCMCfor two-phase system. The proposed correlations predicted the experimental data well.

Keywords: External loop airlift reactor, riser, three-phase, gas holdup, mass transfer coefficient and non-Newtonian fluid.