Experimental investigation of reactive extraction of p-hydroxybenzoic acid using TOA in toluene, petroleum ether and MIBK

ABSTRACT p-hydroxybenzoic acid (p-HBA) remains present in various industrial effluents, it has various industrial applications and excellent medicinal properties, on the contrary, it degrades the fertility of soil if discharged in atmosphere hence, retrieval of p-HBA from effluent is a mandate. In past decades, reactive extraction has arisen as an efficient and attractive separation technique. Therefore, in the present study, the reactive extraction of p-HBA, using Tri-n-octylamine diluted in toluene, petroleum ether, and methyl isobutyl ketone, has been investigated. The results have been reported in terms of efficiency, distribution coefficient, equilibrium complexation constant, and loading ratio. The order of diluents, with respect to extraction given, is MIBK (93.43%) > toluene (92.57%)> petroleum ether (91.43%). The relative basicity model is used to for the interpretation and is found suitable for explaining the results. The diffusion coefficient was also found using Reddy Doraiswamy equation and Wilke Chang equation. Further, minimum number of stages of counter current extraction column and solvent to feed ratio were also calculated to investigate the feasibility of the process.