Waste oil/water emulsions as absorbents for volatile organic solvents abatement

The global VOSs emissions due to tanneries are about 62’000 tons/year of which around 21’000 tons/year are produced by the Italian districts (LIFE00 ENV/IT/000184, ARPAT, 2009). The emissions include both hy drophilic and hydrophobic solvents. Grassi et al. estimated that n-butyl acetate constitutes 77 % of the water-insoluble organic compounds produced by Santa Croce district. Several techniques can be adopted for the VOSs abatement such as thermal incineration, catalytic oxidation, biological degradation, absorption, adsorption, condensation,and membrane separation. The proper VOSs abatement system is selected considering the industrial process, the specie and the concentration of VOSs, and the feasibility of recovery and reuse of the solvents.At the state of the art, tanning industries use absorption towers to treat the air stream using water as sorbent. These systems show high performance to capture powders, pigments, and water-soluble compounds but have low efficiency in the removal of hydrophobic VOSs. The choice of a sorbent suitable for both hydrophilicand hydrophobic VOSs will increase the abatement efficiency of the system. Many studies were carried out testing organic compounds, such as silicon oil and vegetable oil, and their emulsions with water as an alternative to water. In this study, vegetable oil/water emulsions were investigated as absorbents in a bubbler to remove n-butyl acetate (BA) from an air stream.