2019-06, Pérez, Alan, Rodríguez-Barona, Sneyder, Fontalvo, Javier

A new type of liquid membranes called liquid membrane in Taylor flow was integrated to a lactic acid fermentation, using Lactobacillus casei ATCC 393, for lactic acid removal during fermentation. The performance in terms of lactic acid production of the hybrid batch system is compared to a conventional batch fermentation. Lactic acid removal rate increases proportionally with the LA concentration within the fermenter. The lactic acid, the biomass production and the LA productivity in the hybrid system increased by 41.8, 12 and 26.6%, respectively, as compared to the conventional batch fermentation. However, toxicity effects reduce LA to glucose yield in 15.9% as compared to conventional fermentation. Liquid membranes in Taylor flow results promising for enhancing batch and continuous fermentation processes by a hybrid system.

2018, Pérez, Alan, Rodríguez-Barona, Sneyder, Fontalvo-Alzate, Javier

Toxic effects of extractants and carriers of specific microorganisms must be taken into account before using them with hybrid fermentation processes that are combined with liquid membranes or liquid-liquid extraction. In the current research three extractants (trioctylamine, tri-iso-octylamine and Aliquat 336), three diluents (dodecane, dodecanol, and oleyl alcohol) and two mixtures (extractant/diluent) were tested for molecular toxicity on the bacteria Lactobacillus casei ATCC 393 as potential components of a liquid membrane or a liquid-liquid extraction process for lactic acid removal in an intensified fermentation process. Glucose consumption, lactic acid production, and cell growth were used as toxicity indicators. Physical properties of extractants and diluents were related to the molecular toxicity on the microorganism. These results show that mixtures of tri-iso-octylamine/dodecane and trioctylamine/dodecane at a proportion of 1:9 v/v have great potential to be used in liquid membranes or liquid-liquid extraction processes on hybrid fermentations with Lactobacillus casei ATCC 393.

2019, Pérez, Alan, Rodríguez-Barona, Sneyder, Fontalvo, Javier

The liquid–liquid equilibria of systems that involves lactic acid in the aqueous phase and tri-iso-octylamine with diluents as dodecane and 1-dodecanol (active or/and inert) were measured experimentally at three temperatures (306.15, 310.15, and 316.15 K). A previous liquid–liquid equilibrium model that is based on Nernst’s distribution law and mass action law equilibrium equations was extended and generalized for stoichiometric ratios (amine/acid) 1:n. The effect of the diluents and the tertiary amine on the liquid–liquid equilibrium is shown and quantified in terms of the predicted values of the distribution coefficient, chemical equilibrium constants, and temperature. The lactic acid concentration in equilibrium for the organic phase decreases as follows: water/LA/TiOA/1-dodecanol system > water/LA/TiOA/dodecane/1-dodecanol > system water/LA/TiOA/dodecane system.

2016, Pérez, Alan, Rodríguez-Barona, Sneyder, Fontalvo, Javier

Liquid–liquid equilibria of aqueous solutions of lactic acid with trioctylamine diluted in 1-dodecanol was measured experimentally at three temperatures (306.1, 310.1, and 316.1 ± 0.1 K). During the transfer process, lactic acid reacts with trioctylamine to produce an amine–lactate complex. Two models were proposed to predict the liquid–liquid equilibria. The first model considered the equilibrium constant of chemical reaction and the distribution coefficient. Those parameters have been determined by fitting the experimental data. The distribution coefficients have also been experimentally measured. It was found that as temperature increases, the distribution coefficient increases and equilibrium constant decreases. The second proposed model involved the non-random two liquid activity model. Energies of binary interaction and the equilibrium constant of chemical reaction were fitted to experimental data. The equilibrium constant and partition coefficients show the same trends as the first model; however, the first model shows a better prediction as compared to the second model of the liquid–liquid equilibrium data. These two models are especially suitable at low lactic acid concentrations in the aqueous phase where the experimental standard deviation is low.

2019, Pérez, Alan, Gómez, Verónica M., Rodríguez-Barona, Sneyder, Fontalvo, Javier

Lactic acid can be in situ removed from a fermentation broth through reactive liquid extraction or a liquid membrane to enhance the fermentation process. The organic mixture tri-iso-octylamine (TiOA)/dodecanol/dodecane at 10 vol % of the amine is a potential organic mixture for lactic acid removal. Liquid–liquid equilibria with lactic acid aqueous solutions and molecular toxicity on the bacteria Lactobacillus casei ATCC 393 were measured with several dodecanol proportions in dodecane (0 to 90 vol %) and 10 vol % TiOA as potential solvents or membrane phases for LA removal from a fermentation broth. Effects of the organic phase on the bacteria as cell growth, biomass production, glucose consumption, productivity, and product to biomass yield are analyzed. Dodecanol increases the lactic acid chemical equilibrium constant for the liquid–liquid equilibria, while increasing the molecular toxicity on the bacteria. However, for dodecanol concentrations from 30 to 40 vol % the value of the chemical equilibrium constant is high enough for lactic acid distribution between the phases and its toxicity is low enough on the bacteria, making a proper range of dodecanol concentrations for lactic acid removal. Also, the distribution coefficient and the chemical equilibrium constant are fitted as a function of the dodecanol concentration in the organic mixture.