Absorption Of SO2 from SO2/air mixture into sodium citrate buffer solution was performed using air-lift-tube (ALT) absorbers in laboratory and pilot scale. The aim of the study was to improve the efficiency of this regenerative process, to find the proper operation conditions in the air-lift-tube absorbers, and to contribute to the application of this process in the industry. The SO2-removal efficiency was measured while the gas velocity, the inlet SO2 concentration, the liquid hold-up, the sodium citrate buffer concentration and the liquid temperature were changed according to experimental design. Furthermore, the influence of oxidation on the SO2-removal efficiency was measured using SO2/N-2 mixture instead Of SO2/air mixture; the effect of stoichiometric ratio was investigated and the SO2 removal in one and two stages of tube absorbers was measured. The performance of the laboratory and pilot scale ALT absorbers was compared with that of other laboratory and pilot size absorption columns and of some non-regenerative methods. (c) 2005 Elsevier B.V. All rights reserved.