Assessment of the\nRecovery of Erythritol Using Boronic\nAcid Polymers

The development and assessment of novel materials and\ntechnologies\nin the downstream stages is one of the main challenges for the technological\ntransition toward more sustainable and circular processes. Erythritol\nis in high demand as a low-calorie sweetener as well as a substrate\nin the pharmaceutical and cosmetic industries. Nowadays, erythritol\nis produced biotechnologically, and its recovery from complex cultivation\nbroths poses a challenge. In this study, the recovery of erythritol\nfrom a mixture with glycerol and glucose using the adsorption of erythritol\nonto boronic acid polymers was evaluated. <i>p</i>-vinylphenylboronic\nacid was cross-linked by divinylbenzene; the polymer was characterized\nand used as an adsorbent. The adsorption parameters, such as NaOH-to-polyols\nratio and mass of polymer, were optimized. Under the best conditions,\n71% of the initial mass of erythritol was adsorbed, equivalent to\na load of 198 mg of erythritol/g of polymer. Chemical adsorption owing\nto complexation with phenylboronate moieties and physical adsorption\ndue to retention of the gel-type polymer were studied. Highly selective\nerythritol uptake owing to complexation with a separation factor of\nup to 4 was observed, though the contribution of the physical adsorption\nwas responsible for a decrease in overall selectivity. The desorption\nstrategies included washing and a desorption with H<sub>2</sub>SO<sub>4</sub>, resulting in the recovery of 59% of the initial mass of\nerythritol. Shrinkage of the gel-type polymer under acidic conditions\nwas the major challenge in the recovery of the polyols during the\ndesorption. Solid-state <sup>11</sup>B and <sup>13</sup>C NMR spectroscopy\nwere used to examine the adsorption and desorption steps.