A new method to clean industrial water from acetic acid via esterification

The valorisation of very low concentration of acetic acid (6%, w/w) was investigated by reacting with n-butanol and 2-ethyl-1-hexanol taking advantage of the different solubilities of acetic acid and acetic ester in water. The esterification of very diluted solution of acetic acid with alcohol is a reversible reaction and the conversion is greatly restricted by equilibrium limitation. Therefore, the peculiarity of the present method is to shift the reaction equilibrium towards the ester and not towards the reagents, thermodynamically favourite, because of the large amount of water. Different acid catalysts were tested in both homogeneous (sulphuric acid) and heterogeneous phase (polymeric resins and sulphated zirconia) to optimise the process efficiency.