Effect of temperature on equilibria for physical and reactive extraction of protocatechuic acid.

Owing to its biological and chemical applications, the separation of protocatechuic acid, a polyphenol compound, is of interest to researchers. Extraction studies with initial acid concentration (0.001-0.01 kmol m) using aminic extractant tri-n-octyl amine (TOA) (0.2287 kmol m -1.1436 kmol m) in diluent octanol at diverse temperature ranges from 288 K - 313 K was done. Parameters like loading ratio, distribution coefficient, equilibrium complexation constant, diffusion coefficient, number of stages necessary for protocatechuic acid counter-current extraction were obtained; this information is useful in designing a process for the separation of the acid from the fermentation broth as well as from the waste streams. The increase in temperature distribution coefficient was found to increase up to the temperature of 303 K and was found to decrease with a further rise in temperature. The entropy and enthalpy values for the reaction at different temperatures were obtained. The highest extraction of 91.1 % and distribution coefficient of 1.14 were obtained at 313 K for an acid concentration of 0.01 kmol m and TOA concentration of 1.1436 kmol m and 4 stages are required for counter-current extraction process for acquiring the required separation efficiency. Development of 1:1 complex of protocatechuic acid and TOA take place as concluded from the values of the loading ratio.