New Proposal in a Biorefinery Context: Recovery of Acetic and Formic Acids by Adsorption on Hydrotalcites

摘要

Acetic acid (AA) and formic acid (FA) are two of the major fermentation inhibitors found in hemicellulosic hydrolysates. Their removal, which is necessary for the use of hydrolysates as fermentation substrates, can be achieved by adsorption on hydrotalcites. This study aimed to assess the efficiency of hydrotalcites in removing AA and FA from aqueous solution. Kinetic, thermodynamic, and equilibrium experiments were conducted using hydrotalcites composed of 30, 63, or 70% MgO. Calcined hydrotalcites composed of 70 and 63% MgO (MG70c and MG63c) had the best kinetic performance, removing 97% of FA and 91% of AA. The adsorption process followed pseudo-first-order kinetics. The Boyd model showed that external mass transfer or a combination of intraparticle diffusion and external mass transfer controls the process. Adsorption equilibrium was evaluated at different temperatures (30, 40, 50, and 60 degrees C) using MG70c as an adsorbent. The Freundlich model provided the best fit to adsorption isotherms. Thermodynamic studies indicated that adsorption was spontaneous and endothermic in nature. The results confirmed the efficiency of MG70c in removing AA and FA from aqueous solution.