Ion-Exchange Technology for Lactic Acid Recovery in Downstream Processing: Equilibrium and Kinetic Parameters

X Vecino,M Reig,J L Cortina,C Valderrama

doi:10.3390/w13111572

X Vecino, M Reig + Show 2 more

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https://doi.org/10.3390/w13111572

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Abstract

The downstream processing for the separation and purification of lactic acid is a hot research area in the bio-refinery field due to its continuous growing market in different sectors, such as the food, cosmetic and pharmaceutical sectors. In this work, the use of ion-exchange technology for lactic acid recovery is proposed. For that, four anion exchange resins with different polymer structures and functional groups were tested (A100, MN100, A200E and MP64). The sorption process was optimized by the Box–Behnken factorial design, and the experimental data obtained in the sorption process were analyzed by using the response surface methodology and fitted at different isotherms and kinetics models. Moreover, regenerant type, contact time and solid/liquid ratio were evaluated in the desorption process. Results showed that the best resin for lactic acid removal was A100, at pH = 4, with a resin/lactic acid solution ratio of 0.15 g/mL during a maximum of 1 h, achieving 85% of lactic acid removal. Moreover, equilibrium data sorption of lactic acid onto A100 resin was fitted by a Langmuir isotherm and by a kinetic model of a pseudo-second order. In addition, in the desorption process, it was stablished that a resin/regenerant ratio of 0.15 g/mL during 30 min with 0.1 M of NaOH solution provided the best results (4.45 ± 0.08 mg/g).

Highlights

Lactic acid is an alpha-hydroxy acid with dual functional groups, is considered both an alcohol and an acid and has an asymmetric carbon that confers optical activity
In view of the aforementioned, the aim of this study is to evaluate novel types of anionic exchange resins for the lactic acid recovery: one strong base with quaternary ammonium groups gel-type resin (A200E), one weak base containing tertiary amine groups resin with macroporous structure (A100), a weak base macroporous resin containing mixtures of quaternary ammonium and tertiary amine groups (MP64) and a free base macroporous hyper-crosslinked resin containing tertiary amine groups (MN100) in order to evaluate the sorption of lactic acid from water
For the selection of the anion exchange resin, the results of the sorption capacity and percentage of lactic acid extracted were obtained in relation to the sorption process

Summary

Introduction

Lactic acid is an alpha-hydroxy acid with dual functional groups, is considered both an alcohol and an acid and has an asymmetric carbon that confers optical activity. Chemical synthesis from non-renewable sources, such as coal, petroleum products and natural gas In this case, it is mainly based on the hydrolysis of lactonitrile by strong acids, but it can include base-catalyzed degradation of sugars, oxidation of propylene glycol, hydrolysis of chloropropionic acid, oxidation of propylene by nitric acid and reaction of acetaldehyde, carbon monoxide and water at high temperatures and pressures [2,3]; and secondly by ii. 90% of lactic acid production is done by fermentation, since pure lactic acid can be obtained, whereas the chemical synthesis it always gives a racemic mixture [6]

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