Reactive Extraction of Formic Acid by using Tri Octyl Amine (TOA)

Abstract Formic acid is the simplest yet commercially valuable organic acid. It is widely used as a stabilizer and sterile agent in food industries. Reactive extraction is highly effective and selective technique for the recovery of formic acid from dilute solutions. Kinetics study provide rate controlling step (reaction rate or diffusion) that is required to visualize the intrinsic reactive extraction mechanism. Kinetics study of formic acid (0.1–0.4 kmol/m3) extraction with tri-n-octyl amine (TOA) (0.11–0.67 kmol/m3) in n-butyl acetate (NBA) was investigated at temperature 308 ± 1 K. Kinetics study was carried out in a Lewis cell. Effect of formic acid concentration, TOA concentration, speed of stirring, and phase volume ratio were investigated to find the reaction regime. Diffusivity coefficient (DA) of formic acid in NBA was found 3.20 × 10−7 m2/s. Reaction rate constant was evaluated to be 0.616 m3/mol s. The physical mass transfer coefficient (kL) was evaluated to be 0.8278 × 10−6 × N 3.387. The reaction was independent on hydrodynamic parameters and falls under fast reaction regime. The reaction was found first order with respect to both formic acid as well as TOA, occurring in the diffusion film. The findings of the present work are helpful in the selection of commercially viable extraction system and in the design of extractors.

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Reactive Extraction of Lactic Acid, Formic Acid and Acetic Acid from Aqueous Solutions with Tri-n-octylamine/1-Octanol/n-Undecane

ChemEngineering ◽

10.3390/chemengineering3020043 ◽

2019 ◽

Vol 3 (2) ◽

pp. 43 ◽

Cited By ~ 3

Author(s):

Nuttakul Mungma ◽

Marlene Kienberger ◽

Matthäus Siebenhofer

Keyword(s):

Mass Transfer ◽

Acetic Acid ◽

Lactic Acid ◽

Formic Acid ◽

Fermentation Broth ◽

Lactic Acid Production ◽

Mass Action ◽

Reactive Extraction ◽

Technical Application ◽

Pka Value

The present work develops the basics for the isolation of lactic acid, acetic acid and formic acid from a single as well as a mixed feed stream, as is present, for example, in fermentation broth for lactic acid production. Modelling of the phase equilibria data is performed using the law of mass action and shows that the acids are extracted according to their pka value, where formic acid is preferably extracted in comparison to lactic and acetic acid. Back-extraction was performed by 1 M NaHCO3 solution and shows the same tendency regarding the pka value. Based on lactic acid, the solvent phase composition, consisting of tri-n-octylamine/1-octanol/n-undecane, was optimized in terms of the distribution coefficient. The data clearly indicate that, compared to physical extraction, mass transfer can be massively enhanced by reactive extraction. With increasing tri-n-octylamine and 1-octanol concentration, the equilibrium constant increases. However, even when mass transfer increases, tri-n-octylamine concentrations above 40 wt%, lead to third phase formation, which needs to be prevented for technical application. The presented data are the basis for the transfer to liquid membrane permeation, which enables the handling of emulsion tending systems.

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