From normal crosslinking to core-shell structure: Improved performance of β-cyclodextrin based adsorbent toward efficient separation of acetophenone and 1-phenylethanol

To efficiently separate acetophenone (AP) and 1-phenyethanol (PE) from petrochemical by-product, we herein report a novel feasible strategy to fabricate beta-cyclodextrin (beta-CD) based core-shell microsphere, which retains the cage-type crystal structure of beta-CD and superior affinity to AP over PE. Using triphenylmethane-4,4',4 ''-triisocyanate (TTI) as monomer, the polymeric TTI shell can grow in-situ on the surface of beta-CD particles, giving the core-shell structured CD@PTTI. The unique beta-CD core and polymeric TTI shell structure was verified by a series of characterization methods. CD@PTTI-3 exhibits both high AP uptake (ca. 2.07 mmol.g(-1)) and AP/PE selectivity (ca. 7.2), outperforming the conventional TTI cross-linked amorphous beta-CD polymer (TTI-CDP). The adsorption behavior of CD@PTTI-3 on AP and PE single-component solutions was investigated by batch adsorption experiments. Based on the experimental and theoretical results, a mechanism of competitive adsorption of AP and PE on CD@PTTI-3 involving host-guest inclusion, hydrogen bonding and pi-pi stacking is proposed. Furthermore, intense competition between AP and PE on CD@PTTI-3 was observed in column breakthrough experiments, and CD@PTTI-3 could purify AP from 77.16% to 93.6% by a single adsorption-desorption process.