Reversible removal of SO2 at low temperature by Bacillus licheniformis immobilized on γ-Al2O3

Bacillus licheniformis R08 biomass was immobilized on γ-Al2O3 and the effects of R08 biomass loading, SO2 concentration, water vapor, oxygen and temperature on removal of SO2 were investigated. The experimental results indicated that SO2 saturation capacity increased with increasing R08 biomass loading and SO2 concentration, but decreased with increasing adsorption temperature. Water vapor activated the adsorbent and promoted SO2 removal. An increase in oxygen concentration from 5 to 10% had little effect on SO2 removal. FTIR analysis revealed that the R08 biomass bound to γ-Al2O3 mainly by forming R–CO–O–Al bonds. X-ray photoelectron spectroscopy analysis indicated that γ-Al2O3 reacted with SO2 and formed aluminum sulfate in the presence of oxygen when R08 biomass loading was 13.8%, but that amido groups of the R08 biomass reacted with SO2 and formed sulfite when biomass loading was 32.4%. Ten continuous adsorption–desorption cycles showed that the adsorbent had an excellent regeneration performance.