Kinetic and equilibrium analyses of lactate adsorption by Cu-Al and Mg-Al layered double hydroxides (Cu-Al LDH and Mg-Al LDH) and Cu-Al and Mg-Al layered double oxides (Cu-Al LDO and Mg-Al LDO)

Abstract

Lactate is an important metabolite generated during the culture of pluripotent stem cells and is known to inhibit the cell growth. With the increase in the prominence of pluripotent stem cell applications, reliable methods are required to remove metabolites such as lactate for enabling the high-density culture of cells. Herein, we report an investigation of layered double hydroxides (LDHs) and layered double oxides (LDOs) as anion-adsorbents for lactate removal to regenerate the cell culture medium. The lactate absorption ability of Cu-Al and Mg-Al LDH and Cu-Al and Mg-Al LDO adsorbents was evaluated. The influence of various process parameters, including temperature and pH, on the lactate adsorption, were investigated. The kinetics of the adsorption process and equilibrium dynamics were studied, and the maximum adsorption amounts were determined. The Cu-Al LDH, Cu-Al LDO, Mg-Al LDH, and Mg-Al LDO exhibited a lactate adsorption that followed a pseudo-second-order kinetic model, and their apparent activation energies for adsorption were 32.0, 47.4, 95.7, and 61.7 kJ/mol, respectively; these values indicated that chemical adsorption was the underlying mechanism of adsorption. The Langmuir and Freundlich models were analyzed and revealed the nature of the anion-exchange process. This study is expected to promote the high-density culture of cells by ensuring the regeneration of the media by the efficient removal of the undesired lactate.