Cooperative Lactate Capture from Water Using Functionalized Zirconium-Based Frameworks

C2C12 cells have potential applications in many fields; however, their widespread deployment is precluded by the lack of ideal technologies that can efficiently abate the lactate produced by the medium during cell culture. Adsorbents are considered a promising strategy for eliminating lactate from aqueous environments, but remain scarce. Metal-organic frameworks (MOFs) are among the most promising adsorbents for lactate owing to their tunable and mutable-functionalized property. This study assesses lactate uptake at different temperatures and pH values for five types of UiO-66 samples with varying physical and chemical properties. The obtained data are fitted with adsorption kinetics and isotherm models to further investigate their behavior. Analysis of the adsorption data reveals that UiO-66 with tetrafluorinated linkers possesses the best adsorption and selective performance owing to the synergistic combination of μ3-OH/μ3-O on the metal cluster and the C-F functional group on the linkers as well as coordinatively unsaturated Zr⁴⁺ nodes, as evidenced by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy characterizations. The results reveal a mechanistic switch as the lactate protonation state changes with pH, which has not been previously reported for MOFs. Moreover, this study sheds new light on lactate adsorption. These findings provide valuable insights into the judicious design of state-of-the-art materials for lactate-capture applications.