Sorption of perfluorinated compounds from contaminated water to activated carbon

Abstract

Introduction Perfluorinated compounds (PFC) are toxic and bioaccumulative compounds that are ubiquitous in the environment. It is important to develop effective techniques to remove PFC from water. This study is the first to investigate sorption of PFC to activated carbon (AC) at environmentally relevant nanogram per liter concentrations. Methods Batch AC sorption isotherms were measured for water from a contaminated groundwater well, for three perfluorosulfonates and five perfluoroacetic acids. Results For perfluorooctane sulfonate and perfluorooctanoic acid Freundlich sorption coefficients, log K iF , for powdered activated carbon (PAC) were 4.0 and 3.8 (ng/g)(ng/L) -n , respectively, and for granular activated carbon (GAC) were 2.7 and 2.3 (ng/g)(ng/L) -n , respectively. Sorption was nonlinear, with Freundlich n coefficients generally around 0.5. The K iF on both GAC and PAC were PFC chain-length dependant, with increasing number of carbon yielding increasing K iF . This chain-length dependence appeared stronger for perfluorosulfonates than for perfluoroacetic acids. Tests with short (10 min) adsorption times still yielded substantial PFC removal (20-40% for GAC, 60-90% for PAC) and revealed that AC is probably suitable for PFC removal in flow-through systems. A perfluorinated polymer, Teflon, was also tested as a PFC removal agent but proved not to be effective for PFC-contaminated water purification.

Influence of groundwater conditions and co‐contaminants on sorption of perfluoroalkyl compounds on granular activated carbon

“…In contrast, K F values for PFOA sorption from Zhi and Liu () and sorption of PFOS from Senevirathna, Tanaka, Fujii, Kunacheva, Harada, Shivakoti, Okamoto (2010) show a vast difference. There are little differences in Langmuir isotherm parameters reported in the literature and our study with the exception of Hansen, Borresen, Schlabach, and Cornelissen () which used contaminated well water with a very low initial concentration of PFAS and DOC.…”

Perfluoroalkyl substances (PFASs) in wastewater treatment plants and drinking water treatment plants: Removal efficiency and exposure risk

“…PAC has a smaller size compared with GAC, and it has more micropores, surface functional groups and active adsorption sites, leading to the higher adsorption capacity (Yu et al, 2009b). Thus, PAC would adsorb PFASs faster than GAC due to its smaller particle size resulting in larger specific surface area for the same amount of carbon, extra surface functional groups, and shorter internal diffusion distances (Yu et al, 2009b;Hansen et al, 2010). Yu et al (2009b) found GAC and PAC were reached equilibrium at 168 h and 4 h for PFOA and PFOS, respectively.…”

“…Yu et al (2009b) found GAC and PAC were reached equilibrium at 168 h and 4 h for PFOA and PFOS, respectively. An additional explanation of the poorer performance of GAC compared with PAC may be due to the rigidity of the CF 2 backbone which may render its sorption to the inner pore surface area of GAC energetically unfavorable (Hansen et al, 2010).…”

Effect of effluent organic matter on the adsorption of perfluorinated compounds onto activated carbon

“…Studies on fate and behavior of these pollutants in WWTPs implied that they could not be effectively removed by biological treatment process [5]. Various physical-chemical treatment processes, including adsorption [6][7][8], sonochemical treatment [9], reduction with zero-valent iron in subcritical water [10], and membrane filtration [11], have been employed to remove these compounds. Activated carbon adsorption is one of the most promising methods to remove PFCs in aqueous stream due to the effectiveness and low cost.…”