Assessment of the Recovery of Erythritol Using Boronic Acid Polymers

The development and assessment of novel materials and technologies in the downstream stages is one of the main challenges for the technological transition toward more sustainable and circular processes. Erythritol is in high demand as a low-calorie sweetener as well as a substrate in the pharmaceutical and cosmetic industries. Nowadays, erythritol is produced biotechnologically, and its recovery from complex cultivation broths poses a challenge. In this study, the recovery of erythritol from a mixture with glycerol and glucose using the adsorption of erythritol onto boronic acid polymers was evaluated. p-vinylphenylboronic acid was cross-linked by divinylbenzene; the polymer was characterized and used as an adsorbent. The adsorption parameters, such as NaOH-to-polyols ratio and mass of polymer, were optimized. Under the best conditions, 71% of the initial mass of erythritol was adsorbed, equivalent to a load of 198 mg of erythritol/g of polymer. Chemical adsorption owing to complexation with phenylboronate moieties and physical adsorption due to retention of the gel-type polymer were studied. Highly selective erythritol uptake owing to complexation with a separation factor of up to 4 was observed, though the contribution of the physical adsorption was responsible for a decrease in overall selectivity. The desorption strategies included washing and a desorption with H₂SO₄, resulting in the recovery of 59% of the initial mass of erythritol. Shrinkage of the gel-type polymer under acidic conditions was the major challenge in the recovery of the polyols during the desorption. Solid-state ¹¹B and ¹³C NMR spectroscopy were used to examine the adsorption and desorption steps.