Modeling of a Biobutanol Adsorption Process for Designing an Extractive Fermentor

For curbing the severe inhibition and toxicity of 1-butanol in a fermentor, which stand as one of the major hurdles on the way to commercialization of biobutanol production processes, an extractive fermentation process that can remove metabolites during the ferementation can be an effective solution. Among various separation techniques, adsorption using poly-(styrene-co-divinylbenzene) adsorbent resin is an effective and energy-efficient technique that holds much promise. In this paper, we have investigated the adsorption-and-desorption characteristics of the fermentation metabolites to aid the design of a new fermentation process equipped with an in situ or ex-situ butanol recovery capability. Specifically, the Langmuir equation and Ideal Adsorption Solution theory (IAST) have been used for developing an adsorption isotherm model, based on which a kinetic model of the adsorption process is developed. For the parameter estimation of the adsorption model, experiments have been carried out with a batch type slurry adsorption process processing a multiple-component mixture containing acetone, ethanol, 1-butanol, acetic acid, and butyric acid. It is subsequently confirmed that the adsorption model developed with data from the experiments using the model broth adsorption can accurately predict the adsorption behavior of the actual fermentation broth. To ensure the practical applicability of the adsorption process, desorption experiments of the adsorbent resin have also been performed. It is found that approximately 95% of the adsorbates on the adsorbent can be recovered using 140 °C steam with the steam-to-adsorbent mass ratio of 1. This study on the adsorption-and-desorption characteristics is expected to contribute to designing a large-scale extractive fermentor for biobutanol production.