Chemical route for synthesis of citric acid from orange and grape juices

Abstract

Citrus fruits contain sufficient citric acid which is a main tricarboxylic acid. The properties of citric acid make it an important additive in various process industries. The aim of this experimental study is to produce citric acid from orange and grape juices. The chemical route for synthesis of citric acid from citrus juices involves three steps: (i) Neutralization to adjust pH (9-11) with 2.8 M NaOH solution, (ii) Addition of CaCl2 solution (40.3-41.1% (w/v)), and (iii) Acidification with H2SO4 solution (1.5-2.3 M) to produce citric acid. In this study, the fruits were peeled, crushed, filtered, neutralized, added CaCl2 solution and acidified to obtain citric acid. The experiments were carried out by varying final pH of solution, concentrations of CaCl2 and H2SO4 solutions maintaining volume constant. A maximum yield of citric acid at 91.1 and 79.8% from orange and grape fruits at optimum final pH of solution, concentrations of CaCl2 and H2SO4 solutions at 10, 40.7% (w/v) and 1.9 M respectively were achieved. Finally, the purified citric acid crystals were characterized using FTIR and XRD. Thus, it could be concluded that orange fruit would be a promising source for the production of citric acid than grape.