Equilibrium and kinetic investigation of reactive extraction of pyridine-2-carboxylic acid using corn oil as diluent

Toxic chemical release is the major issue of concern of the industrial effluents. Hence, recovery of chemicals from effluent stream is of great research interest. Present investigation was focused on recovery of pyridine-2-carboxylic acid (picolinic acid) from aqueous streams by reactive extraction using corn oil as a non-toxic diluent. Attempts have been made to estimate the recovery of picolinic acid by chemical extraction and to investigate its kinetic parameters. The kinetic modeling was also carried out for chemical extraction by the law of mass action. Extraction equilibria had been reported and effect of acid concentration, agitation speed and extractant-diluent composition were studied at room temperature. Kinetic study reveals very slow, first order reaction in acid concentration and zero order in extractant, tri-butyl phosphate. The reaction rate constant of 0.191 s⁻¹ suggests a slow type of reaction. The diffusivity of picolinic acid in corn oil was found to be 7.0170 × 10^–11 m² s⁻¹. Although the distribution coefficient is very low and reaction is infinitely slow, the non-toxicity of corn oil used in this study is the key parameter for its use as diluent.