High silica zeolites as an alternative to weak base adsorbents in succinic acid recovery

Initial studies were performed on succinic acid adsorption from aqueous solutions by zeolite powders. CVB-28014 (high-silica ZSM-5) showed higher equilibrium loadings (up to 0.16 g/g) than CBV-901 and CP811C-300, and was used for follow up studies. In the presence of Na⁺ counterions, the succinic acid adsorption decreased in parallel with the succinic acid dissociation, but the adsorbent also showed some affinity toward sodium hydrogensuccinate with selectivities in the range 10-20 toward succinic acid. The presence of acetic acid resulted in lower succinic acid loadings but the capacities remained sufficient for efficient recovery. The selectivity between succinic acid and acetic acid ranged from 1 to 6. Increasing the temperature to 70 d̀C reduced the equilibrium loadings, but in ethanol the succinic acid loadings showed a more significant drop. Therefore, regeneration might be achieved by using an adsorption-competitive solvent like ethanol. The current results suggest that this may lead to an attractive option for the recovery of succinic acid from fermentation media. Hydrophobic rather than ionic interactions are used, thus avoiding regeneration involving acid and base and the associated waste salt production.