Adsorption and the subsequent desorption of lactic acid molecules on zirconium metal-organic frameworks: An innovative and efficient approach for the recovery of the produced lactic acid from fermentation broth

Nowadays, biomass-derived lactic acid serves as a significant foundational chemical in the pursuit of sustainable production of various materials. Nevertheless, the current fermentation process faces limitations due to the challenging retrieval of the lactic acid product from the fermentation broth, resulting in the production of gypsum waste in stoichiometric quantities. In this work, we demonstrate the efficacy of Zr-UiO-66 metal–organic frameworks (MOFs) as effective adsorbents in the process of recovery of lactic acid from the fermentation broth. The MOF beads have been manufactured successfully and were applied to recover lactic acid from the solution and the experimental conditions were optimized. The results show that Zr-UiO-66 adsorbent has a good ability of up to 98.8% to adsorb the produced lactic acid from its fermentation broth at a pH value of 6.5, adsorbent (MOF) dosage of 0.625 g, an initial concentration of 15 mg/L, temperature of 298 K, within process time of 4 h. The data obtained from the adsorption process demonstrated a satisfactory fit with the Langmuir isotherm model (with a R² of 0.958), kinetics (with a R² of 0.970), and thermodynamic results, confirming the spontaneous and exothermic nature of the adsorption process. The regeneration experiment of the MOF beads showed that the adsorption efficiency of Zr-UiO-66 remained above 90% even after undergoing seven cycles.