Solid-phase extraction of d-glucaric acid from aqueous solution

Since d-glucaric acid was produced by Escherichia coli and other microorganism, the purification of d-glucaric acid has been an important issue for downstream production. This work studied the adsorption of d-glucaric acid by means of seven ion exchange resins and three non-ionic adsorbents. Ion exchange resins showed superiority in adsorption capacity. Their isotherms could be fitted by Freundlich equation at pH 3.9 and Langmuir equation at pH 6.0, respectively. The highest adsorption capacity is 350 mg/mL at pH 3.9 by using 335 ion exchange resin. Compared to ion exchange resins, non-ionic adsorbents showed less capacity and Freundlich isotherm was suitable for both pH conditions. For adsorption kinetics, pore diffusion model and surface diffusion model were combined with Freundlich isotherm to study the uptake rate of ion exchange resins. 335 resin has the pore diffusion coefficient of 18.3 × 10−10 m2/s and the surface diffusion coefficient of 1.29 × 10−11 m2/s. Generally, 335 resin is the best choice for d-glucaric acid adsorption owing to its superior capacity and diffusivity as well.