Batch screening of weak base ion exchange resins for optimized extraction of acetic acid under fermentation conditions

Abstract

Acetic acid is a valuable chemical with high demand for applications in food, pharmaceutical, polymer and other industries. A total of 10% acetate in the world is produced through bio-based processes such as fermentation. Such processes require cost-effective separation technologies to make the bio-acetate product competitive on the markets. Ion exchange resins can efficiently extract acetate from the fermentation broths and due to their re-usability after regeneration, can be cost-effective with lower operation and maintenance costs. To facilitate better process design, kinetics of acetate adsorption by six different basic ion exchange resins: Amberlite FPA-53, Amberlite IRA-67, Dowex-66, Dowex Marathon WBA-2, Amberlite IRA-96 and Amberlite IRA-400; was studied using well-known linear and non-linear adsorption isotherm models. The study showed that Amberlite FPA-53 (213 mg/g wet resin) had the highest acetate adsorption capability followed by Amberlite IRA-67 (202 mg/g wet resin) and Dowex-66 (191 mg/g wet resin). Of the tested models, the acetate adsorption onto these resins was found to fit well with the Langmuir model. It was found that there was a significant effect of acetic acid concentration and pH on acetate adsorption using gel-type and macroporous resins, especially at high initial concentrations of acetate in the broth. The study further showed, that under fermentation conditions (pH of 5–7), the adsorption capacity of all the resins was lower than at the pKa for acetic acid.