Surface-associated metal catalyst enhances the sorption of perfluorooctanoic acid to multi-walled carbon nanotubes

Abstract

Surface-associated metal catalyst enhances the sorption of perfluorooctanoic acid to multi-walled carbon nanotubes Journal of Colloid and Interface Science, 377, 342-346, 2012 2 AbstractPerfluorooctanoic acid (PFOA) sorption behaviour of two commercial multi-walled carbon nanotubes (MWCNTs) (C 150 P from Bayer MaterialScience: BA and C-MWNTs from NanoTechLabs Inc.: CP) was investigated from aqueous solution. The BA nanotubes contain Co/Mn/Mg/Al catalysts both on their outer surface and in the inner bore while CP contains Fe-based catalyst typically within the tubes. The adsorption isotherms of 14 C-radiolabeled PFOA were measured by batch experiments and fitted to the Freundlich model (r 2 0.92).. The adsorption affinity and capacity on BA were significantly higher than on CP. Increasing the pH reduced the adsorption of PFOA due to the electrostatic interaction between the pH-sensitive surface and the adsorbate. Increasing NaCl concentration lead to the aggregation of the MWCNTs reducing the available surface and thus the adsorption capacity. Removal of the catalyst from the outer surface of BA changed the electrophoretic mobility from positive to negative value also decreasing the adsorbed amount of PFOA. The surface charge of the surface-associated metal catalyst favors the electrostatic sorption of PFOA. Such surface modification may be a promising way to improve the sorption capacity of MWCNTs for pollutants like PFOA and to broaden their potential application in water purification.Keywords: Perfluorooctanoic acid; multi-walled carbon nanotubes; metal catalyst; sorption Chengliang Li, Andreas Schäffer, Jean-Marie Séquaris, Krisztina László, Ajna Tóth, Etelka Tombácz, Harry Vereecken, Rong Ji, Erwin Klumpp Surface-associated metal catalyst enhances the sorption of perfluorooctanoic acid to multi-walled carbon nanotubes

Co-transport of multi-walled carbon nanotubes and sodium dodecylbenzenesulfonate in chemically heterogeneous porous media

“…Carbon nanotubes (CNTs) consist of rolled-up graphene sheets (Iijima, 1991) that have been used in many commercial applications such as electrical cables and wires (Janas et al, 2014), hydrogen storage (Dillon et al, 1997), solar cells (Guldi et al, 2005), radar absorption (Lin et al, 2008), and may potentially be employed in environmental remediation (Mauter and Elimelech, 2008;Pan and Xing, 2012) and water treatment (Camilli et al, 2014;Li et al, 2012;Zhang et al, 2010). The widespread use of CNTs will undoubtedly result in their release into the environment (Gottschalk et al, 2009).…”

“…Previous research with CNTs and surfactants focused on determination of breakthrough curves (BTCs), but did not measure the influence of surfactants on CNT retention profiles (RPs) (Lu et al, 2013;Lu et al, 2014). Liang et al (2013) demonstrated that the presence of surfactants had a large influence on the shape of the RPs for silver nanoparticles in quartz sand, but little influence on their BTCs. This was attributed to competitive blocking (e.g., filling) of silver nanoparticle retention sites by surfactant.…”

Roles of cation valance and exchange on the retention and colloid-facilitated transport of functionalized multi-walled carbon nanotubes in a natural soil

“…They have been utilized in numerous commercial applications (Gohardani et al, 2014) such as electrical cables and wires (Janas et al, 2014), solar cells (Guldi et al, 2005), hydrogen storage (Jones and Bekkedahl, 1997), radar absorption (Lin et al, 2008) and considering as absorbents for environmental remediation and water treatment (Camilli et al, 2014;Li et al, 2012;Mauter and Elimelech, 2008;Pan and Xing, 2012;Zhang et al, 2010) due to their unique electric, chemical, and physical properties. The widespread commercial and potential environmental applications will undoubtedly result in their release into the subsurface.…”

“…These suspensions were dispersed by ultrasonicating the stock suspension for 15 min at 65 W, and then repeating this process 10 min before injection into soil columns. This low energy of sonication does not damage the MWCNTs (Li et al, 2012).…”

Sorption of perfluorooctanoic acid, perfluorooctane sulfonate and perfluoroheptanoic acid on granular activated carbon

“…Because of their high chemical stability, PFAAs have not been shown to be effectively degraded using biological or chemical treatment technologies, and thus physical sorption is the primary option currently available for their removal from water. Activated carbon (AC) has a long history in environmental applications as a sorbent for purifying drinking water and wastewater (Karanfil and Kilduff, 2000;Li et al, 2002), including for PFAAs removal (Yu et al, 2009;Li et al, 2012). AC exhibits superior adsorptive capacity for organic pollutants in aqueous solution because of its porous structure, large surface area and diverse surface chemistry (Rozwadowski et al, 1979;Qu et al, 2009).…”