Efficient and selective adsorption of small polyols by boronic acid functionalized polystyrene adsorbent

BACKGROUND The separation of polyols from fermentation broth remains a challenge due to their high boiling points and strong hydrophilicity, however, they show pH-dependent reversible interaction with boronic acid, which makes it a perfect moiety for the construction of functional adsorbents for polyols enrichment. RESULTS Boronic acid functionalized polystyrene adsorbents were successfully synthesized by loading N- or O-substituted phenylboronic acid into chloromethylated polystyrene resin. Aminophenyl boronic acid modified resin exhibits the best adsorption capacities, 0.34 mmol g(-1) for glycerol and 0.27 mmol g(-1) for 1,2,4-butanetriol in aqueous solution, whereas the adsorption capacities of most commercial resins are below 0.07 mmol g(-1). The adsorption capacity increased with increasing alkalinity and the boronic ester dissociates when subjected to acidic conditions. The reversible interaction facilitates regeneration of the adsorbent, and the resin displayed good adsorption stability during six reuses. CONCLUSION The functional resin displays great adsorption advantage over commercial resins and adsorptive preference for 1,2- and 1,3-polyols rather than 1,4-polyol in double-adsorbate systems, distinctive from commercial resin whose adsorption capacity is mainly determined by the hydrophilicity of the adsorbate. Thus, boronic acid functionalized polystyrene adsorbent is a potential adsorbent for polyol enrichment from fermentation. (c) 2018 Society of Chemical Industry