Modeling and Optimization of Reactive Extraction of Isonicotinic Acid Using Tri-n-octylamine in Biocompatible Diluents Mixture: Response Surface Methodology and Regeneration of Solvents

The present study is aimed to recover the pharmaceutically and biochemically important compound, isonicotinic acid (iNA) from aqueous/fermentation broth in a biocompatible extraction system using an intensified approach, reactive extraction. Tri-n-octylamine (TOA) is used as extractant in nontoxic diluent mixtures of dodecane and n-decanol (modifier) in 1:1 v/v. However, modeling and optimization of reactive extraction using three process parameters, that is, initial iNA concentration in aqueous solution (0.0032-0.0368 kmol.m(-3)), TOA concentration in organic phase (0.110-1.259 kmol.m(-3)) and initial pH values of aqueous phase (1.32-4.68) is performed using response surface methodology (RSM), and the rotatable central composite design (rCCD) matrix is used in the experimental design. The RSM model suggests that initial acid concentration is the most influential factor, whereas pH value change shows antagonistic impact on %E. At equilibrium, under constraint condition (lowest TOA concentration selected) that is, 0.110 kmol.m(-3) and iNA concentration of 0.03 kmol.m(-3) and pH value of 3.76, the maximum predicted value of % E is found to be 91.13%. The corresponding experimentally determined degree of extraction is 89.4% which is in close agreement with the value predicted by the model. Nevertheless, the back extraction of iNA is also carried out using different concentrations of aqueous solution of NaOH. It is found that 99% of iNA is recovered using 0.02 kmol.m(-3) NaOH with solvent regeneration.