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Enhanced sorption of perfluorooctane sulfonate (PFOS) on carbon nanotube-filled electrospun nanofibrous membranes
- Dai, Yunrong, Niu, Junfeng, Yin, Lifeng, Xu, Jiangjie, Sun, Kang
- Chemosphere 2013 v.93 pp. 1593-1599
- aqueous solutions, carbon, electrostatic interactions, hydrophobic bonding, models, nanofibers, pH, sorption, sorption isotherms, surface area, tensile strength
- Multi-walled carbon nanotube-filled electrospun nanofibrous membranes (MWCNT-ENFMs) were prepared by electrospinning. The addition of MWCNTs (0.5wt.% vs. ENFMs) doubled the specific surface area and tensile strength of the ENFMs. The MWCNT-ENFMs were used to adsorb perfluorooctane sulfonate (PFOS) in aqueous solutions. The sorption kinetics results showed that the sorption rate of PFOS onto the MWCNT-ENFMs was much higher than the sorption rate of PFOS onto the pure ENFMs control, and the pseudo-second-order model (PSOM) described the sorption kinetics well. The sorption isotherms indicated that the sorption capacity of the MWCNT-ENFMs for PFOS (16.29±0.26μmolg−1) increased approximately 18 times, compared with the pure ENFMs (0.92±0.06μmolg−1). Moreover, the solution pH significantly affected the sorption efficiency and sorption mechanism. The MWCNT-ENFMs were negatively charged from pH 2.0–10.0, but the electrostatic repulsion between the MWCNT-ENFMs and PFOS was overcome by the hydrophobic interactions between PFOS and the MWCNTs or nanofibers. The strong hydrophobic interactions between PFOS and the MWCNTs played a dominant role in the sorption process. For the pure ENFMs, the electrostatic repulsion was conquered by the hydrophobic interactions between PFOS and the nanofibers at pH>3.1. In addition to the hydrophobic interactions, an electrostatic attraction between PFOS and the pure ENFMs was involved in the sorption process at pH<3.1.