Removal of p-chlorophenol from aqueous solutions by carbon nanotube hybrid polymer adsorbents

Abstract

Aiming to remove chlorophenols from aqueous solution, carbon nanotube (CNT) hybrid polymer beads were fabricated via the phase inversion method, and were adopted as adsorbents to remove p-chlorophenol in this study. The CNT hybrid bead was composed of a smooth outer surface and hierarchical porous inner structure, with worm-like CNTs lying on/embedded in the polymer slices. The incorporation of CNTs in the polymer beads resulted in a dramatically improvement of the surface area. The adsorption kinetics and isotherms of p-chlorophenol from aqueous solutions on CNT hybrid adsorbents were studied, and the impacts of temperature and pH value on the adsorption were also explored. The adsorption capacity of CNT hybrid adsorbents towards p-chlorophenol was significantly superior to that of the neat polymer adsorbent and pristine CNT. And the CNT hybrid adsorbents also showed an outstanding separation performance from water treatment system after adsorption. The adsorption process of p-chlorophenol on CNT hybrid adsorbents was found to be an exothermic process, and physical adsorption was the predominant mechanism. The neutral p-chlorophenol molecule was a more effective form for adsorption than was the ionic form. The interaction between p-chlorophenol and the CNT hybrid adsorbents responsible for the adsorption was assumed mainly non-polar forces such as hydrophobic interactions and π–π electron coupling.