Intensification of nicotinic acid separation using organophosphorous solvating extractants by reactive extraction

Abstract

Nicotinic acid (3-pyridine carboxylic acid) is widely used in food, pharmaceutical, and biochemical industries. Compared to chemical methods, enzymatic conversion of 3-cyanopyridine is an advantageous alternative for the production of nicotinic acid. This study is aimed to intensify the recovery of nicotinic acid using reactive extraction with organophosphorus solvating extractants such as tri-noctyl phosphine oxide (TOPO) and tri-n-butyl phosphate (TBP). The distribution of nicotinic acid between water and phosphorus-based solvents dissolved in various diluents and the comparison of extraction efficiency with pure diluents are studied at isothermal conditions. Pure diluents are not found to be good extracting agents and the maximum distribution coefficient (KD) obtained with 1-octanol is 0.31. Experimental studies are carried out to investigate the effect of diluent, initial acid concentration, extractant type, and extractant composition on the degree of extraction. The maximum recovery of nicotinic acid is obtained by dissolving TOPO in MIBK at an initial nicotinic acid concentration of 0.10 kmol/m3. Solvation numbers and extraction equilibrium are also estimated with both TBP and TOPO. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.