Highly efficient separation and removal of fluorinated liquid crystal monomers employing N-doped coconut shell-based...

Fluorinated liquid crystal monomers (F-LCMs) have been considered as emerging organic pollutants. Efficient isolation and removal of F-LCMs in aqueous samples is essential to protect ecological environment and human health. However, studies about the treatment and removal of F-LCMs are limited. In this study, N-doped biocarbon adsorbent (N@BA) was prepared from coconut shell-based porous carbon by one-step activation and pyrolysis with KOH and urea. Results disclosed that the modification not only introduced favorable functional groups but also increased the surface area from 763 m²/g to 908 m²/g. Under the optimal removal conditions, the N@BA displayed satisfactory adsorption performance towards F-LCMs, the maximum adsorption capacities ranged from 1.25 mg/g to 1.43 mg/g, and the removal rates of F-LCMs in real environmental waters varied from 86.6 % to 91.4 %, which apparently higher than that obtained on unmodified carbon (57.1-67.7 %) and commercial active carbon (65.5-76.3 %). Studies about the adsorption mechanism disclosed that the removal procedure of N@BA towards F-LCMs belonged to chemisorption-dominant single molecule layer adsorption, multiple forces such as H-bonding, π-π stacking and hydrophobic interactions co-contributed to the adsorption. The satisfactory results well confirms that N@BA is a cost-effective and sustainable adsorbent for the efficient removal of F-LCMs from waters.