Intensification of Recovery of Nicotinic Acid Using Reactive Extraction: Equilibrium Study

Nicotinic acid is widely used in the food, pharmaceutical and biochemical industries. Fermentation technology for the production of nicotinic acid in particular has been known for more than a century and acid have been produced in aqueous solutions. Reactive liquid-liquid extraction for the recovery of the organic acids by a suitable extractant has been found to be a promising alternative to the conventional processes. For the design of extraction process, equilibrium data of extractant is required to select the proper extractant for reactive extraction. The conventional extractants, such as simple hydrocarbon, ketone, kerosene oil and alcohol are used to carryout the physical equilibrium experiments for reactive extraction of nicotinic acid. These extractants are not able to fulfill the basic requirements often because of their low distribution coefficients. The maximum distribution coefficient (KD = 0.51) is obtained with 1-octanol. Tri-n-butyl phosphate (TBP) with various diluents is used to perform equilibrium experiments of reactive extraction of nicotinic acid. The distribution coefficients are calculated with various extractant systems in equilibrium. Effect of nicotinic acid concentration on distribution coefficient has also been studied. Pure TBP is showing maximum recovery of nicotinic acid with distribution coefficient (KD = 0.87).at an initial acid concentration of 0.105 kmol/m 3 . INTRODUCTION Over the last 3 decades, there has been a resurgence of interest in large-scale production of fermentation chemicals due to the sharp increase in petroleum cost. So the potential role of a new energy efficient fermentation technology is receiving growing attention. The current economic impact of fermentation chemicals, however, is still limited, in large part because of difficulties of product recovery. Thus, for fermentation products to penetrate the organic chemicals industry, substantial improvements in the existing recovery technology are needed. Organic acids, widely used in the food, pharmaceutical and chemical industries, are important chemicals. Fermentation technology for the production of organic acids in particular has been known for more than a century and acids have been produced in aqueous solutions. Reactive liquid-liquid extraction of the organic acids by a suitable extractant has been found to be a promising alternative to the conventional processes [1]. This method is advantageous for alcohol and organic fermentations [2]. Some of the advantages include increased reactor productivity, ease in reactor pH control without requiring base addition, and use of a high-concentration substrate as the process feed to reduce process wastes and production costs. This method may also allow the process to produce and recover the fermentation product in one continuous step and reduce the down stream processing load and the recovery costs. Nicotinic Acid (also called Niacin) is an important carboxylic acid. Severe lack of niacin causes the deficiency disease pellagra. Niacin has proved to be useful as a food additive and in pharmaceuticals. The main sources of nicotinic acid are fruits, plants and seeds [3]. Three major factors have been found to influence the equilibrium characteristics of extraction of carboxylic acids from aqueous solutions, i.e., the nature of the acid, concentrations of acid and Tributyl Phosphate (TBP), and the type of diluent [4-6]. Process considerations dealing with the competition between physical extraction and the chemical interaction of hydrophobic acids remain a challenging problem since such systems show extremely nonideal behavior.