Solvent Extraction of Citric Acid with Different Organic Phases

Abstract

The present work aimed at the study of citric acid solvent extraction in order to establish the composition of the organic phase and to obtain thermodynamic and kinetic data for the chosen system. Discontinuous extraction experiments in a single stage were performed from a synthetic solution of citric acid, with the typical concentration (10% w/v) observed in industrial fermented musts. Exploratory experiments were carried out using different organic phases in order to select the most suitable solvent phase to further continuous extraction tests in a mechanically agitated column. The selected organic phase composition was: Alamine ® 336, Exxal ™ 13 tridecyl alcohol, and the aliphatic diluent Escaid TM 110. Next, the effects of the contact time and of the concentrations of extractant and modifier on the citric acid extraction were studied. Among the investigated conditions, the best one was 10 minutes of contact time, 30% w/v of Alamine ® 336, and 10% w/v of Exxal ™ 13 tridecyl alcohol. For this condition, the equilibrium isotherm (28˚C ± 2˚C) was determined, and the equilibrium constant was calculated ( ). It was considered that trioctylamine and citric acid complexation reaction occurs mainly with non-dissociated citric acid form, because the aqueous feed solutions' pH is lower than the citric acid pK a1 . It was found that 1.5 molecules of the extractant, on average, are required to react with one citric acid molecule, which can indicate that reactions with different extractant/citric acid ratios occur simultaneously. Next, the rate constants for the direct and inverse reactions, 2.10 (mol•L , respectively, were calculated. Coefficients of determination (R 2 ) values higher than 0.93 were found in these calculations, suggesting that the results obtained using a computer modeling would be very close to those results obtained experimentally. Therefore, the present work provides data required to future modelling, design, and simulation of citric acid solvent extraction processes.How to cite this paper: Araújo, E.M.R.,

State of the Art on the Microbial Production of Industrially Relevant Organic Acids

“…Calcium sulfate is filtered off, whereas citric acid undergoes further purification steps. An alternative method for CA recovery is based on liquid-liquid extraction with various solvents (such as aliphatic alcohols, ketones and tertiary amines) [47,48]. More recently, other methods have been proposed, such as supercritical CO 2 [49], adsorption on cationic resins and electrodialysis [50,51].…”

Conversion of Calcium Citrate to Citric Acid with Compressed CO2

“…Various methods have been developed toward separation and purification of citric acid as alternatives. For instance, liquid–liquid extraction (alcohols and ketones) − and reactive extraction (amines dissolved in various diluents) − of citric acid from fermentation broth have been found to be a promising alternative to the conventional process, avoiding consumption of calcium carbonate and sulfuric acid (Scheme , path b). However, some of the solvents are toxic, volatile, and flammable, which limit their applicability in practice.…”

Liquid–Liquid Equilibria for Trioctylamine/1-Dodecanol/Citric Acid/Water System at 303.1 and 308.1 K: Experimental Data and Prediction

“…These amines can be used in liquid extraction processes, in one or more countercurrent stages, and for liquid membranes, which require less use of solvent or extraction agents. Among the amines, trioctylamine (TOA) has shown high extraction efficiencies. ,− However, high-molecular-weight amines must be used in the form of solutions in organic diluents because of their physical properties. It has been noticed that diluents, either because of their molecular size, polarity, or ability to form hydrogen bonds, significantly affect the extraction behavior of an amine in terms of complex formation and solvation.…”

“…The extraction of CA with alamine 336 (30%) and 10% w/v of various alcohols (pentanol, decanol, dodecanol, and tridecanol) in Escaid at 30 °C with 10 min of contact time is virtually the same, between 81 and 86%. Turbidity was observed during the organic phase, which dissipated over time …”