Performance and mechanisms for removal of perfluorooctanoate (PFOA) from aqueous solution by activated carbon fiber

The sorption behavior of perfluorooctanoate (PFOA) by activated carbon fiber (ACF) in aqueous solution was investigated. The sorption of PFOA on ACF followed pseudo-second-order kinetics and the sorption equilibrium was reached at approximately 6 h. The sorption of PFOA on ACF fitted the Freundlich model well. The sorption capacity of PFOA by ACF decreased with increasing pH, indicating that electrostatic attraction (pH < 7.4) and repulsion (pH > 7.4) existed in the sorption process. Dissolved organic matter (DOM) inhibited the sorption of PFOA on ACF and no obvious sorption was observed when the concentration of DOM was increased to 500 mg L-1. This was primarily because of the competitive sorption between DOM and PFOA, and the blockage of ACF pores by DOM. The results indicated that electrostatic interactions, hydrogen bonding interactions, and hydrophobic interactions were responsible for the fast sorption, and the formation of hemi-micelles and micelles of PFOA further promoted the sorption of PFOA on ACF.