SEPARATION OF O-CHLOROBENZOIC AND P-CHLOROBENZOIC ACIDS - HYDROTROPY AND PRECIPITATION

The aqueous solubilities of o- and p-chlorobenzoic acids (CBAs) in dif ferent concentrations of sodium butyl monoglycol sulphate (NaBMGS) sol utions at 25 and 45 degrees C are determined by the weight disappearan ce method. The precipitation of o- or p-CBA by dilution with water fro m their single component NaBMGS solution is carried out in a 2 L agita ted jacketed crystallizer. The crystal size distributions (CSDs) of th e precipitated solids are determined using a multichannel Coulter coun ter. The effects of significant process variables, namely, temperature , water addition flow rate and speed of agitation on the CSDs are inve stigated in a series of batch experiments. The results are analysed by the method of s-plane analysis and correlations between the nucleatio n and growth rates are presented.