Lactic acid recovery from date pulp waste fermentation broth by ions exchange resins

Abstract

The recovery of lactic acid (LA) from fermentation broth remains a challenge considering its purity and purification cost. The use of ion-exchange resins to recover lactic acid (LA) from the broth of date pulp waste fermented with indigenous bacteria was explored in this study. For this purpose, commercially available AmberliteIRI-67 and IR-120 resins were utilized to purify and recover LA from the broth. The effect of pH, initial concentration, and binding ability was optimized in the initial set of experiments. LA was extracted from the fermentation broth by a weak anion exchanger followed by a cation exchanger. The maximum adsorption capacity of LA (150 mg/g) was observed with weak anion resin at an initial pH 3. The pH showed a significant effect, and a pH value below the pKa of LA was found to be favorable for high adsorption capacity. In a fixed-bed column, 91% LA recovery with 94.6% optical purity was achieved from real fermentation broth. Both resins remained stable during the recovery of LA. Successful desorption and regeneration (98.2% recovery of LA) of the anion-exchange resin was achieved using 1 M HCl as an eluent. Compared to the Freundlich model, the Langmuir and Dubinin–Radushkevich isotherm model (R 2 = 0 .90-0.99) matched the experimental results fairly well. The results of this study showed that the ion exchange chromatography technique with weak anion and strong cation exchangers has the potential to be used for LA recovery from fermentation broth. • LA extracted from the fermentation broth by a weak anion followed by a cation exchanger. • The maximum adsorption of LA (150 mg/g) was observed with weak anion resin at an initial pH 3. • In a fixed-bed column, 91% LA recovery with 95% optical purity from the fermentation broth was achieved. • Successful desorption (98.2% LA) of the anion-exchange resin with 1 M HCl was achieved. • Langmuir and DR isotherm model (R 2 90-99) matched the experimental results fairly well.