A facile synthesis of hyper-cross-linked polystyrene resins for phenol removal

Hyper-cross-linked polystyrene networks (HPNs) were obtained from macroporous slightly cross-linked polystyrene by using inexpensive and commercial dichloroalkanes as external cross-linkers via a two-step Friedel-Crafts reaction. In this reaction, AlCl3 or FeCl3 was used as catalyst, and the highest Brunauer-Emmett-Teller (BET) surface area (S-BET) of the HPNs was amounted to 832.8 m(2)/g using a starting polymer with a S-BET of 19.5 m(2)/g. The results showed that physical properties such as surface area and swelling behaviors of the HPNs could be regulated by varying the strut length and structure of cross-linkers. The sorption performance of the HPNs for phenol was greatly improved due to both adsorption on the surface and absorption in the matrix through framework swelling. The equilibrium adsorption capacity of phenol on HPN-DCM-DCE reached 24.5 mg/g and 170.0 mg/g at the equilibrium concentration of 2 mg/L and 200 mg/L, respectively. The equilibrium isotherm and sorption kinetic studies indicated that the sorption behaviors could be well fitted with Freundlich isotherm equation and the pseudo-second-order rate equation.

Automated summary

This study successfully synthesized hyper-cross-linked polystyrene networks with high surface area through a two-step reaction, showing that the physical properties can be adjusted by changing the structure of cross-linkers to enhance the adsorption performance for phenol.