Perfluorooctane sulfonate (PFOS) has been increasingly considered an environmental micropollutant in recent years. The adsorption of PFOS by anion exchange resins and granular activated carbon was studied in this work. Additionally, the regeneration and reusability of the selected resin were further studied. The equilibrium adsorption data were fitted well by the Freundlich isotherm for all adsorbents. PFA300 had the highest adsorption capacity (455 mg/g) and the fastest adsorption rate. Regeneration studies of PFA300 were conducted using different types of regeneration solutions. The regeneration efficiency of PFA300 exceeded 99%. Regenerated PFA300 was reused as an adsorbent and showed high PFOS removal efficiency for six cycles. In this study, PFA300 had the highest adsorption capacity as well as good regeneration and reusability. Therefore, PFA300 is a promising adsorbent that can be used to remove PFOS in aqueous solution.

A B S T R A C TPerfluorooctanoic acid (PFOA) has become a global concern due to its toxicity and persistent nature. It has been detected in water environments in recent years. Therefore, removal techniques are essential for minimizing human health risks and environmental impacts. The main objective of this study is to investigate the efficiency of adsorbents in the removal of batch and column PFOA. Batch adsorption experiments were conducted to study four adsorbents (PFA300, Dow Marathon A, XAD4, and GAC). The equilibrium adsorption data fitted well to the Freundlich isotherm for all adsorbents. PFA300 exhibited the maximum adsorption capacity (Freundlich K f value = 117). The continued removal of PFOA was conducted by column. PFA300 exhibited the best performance over the longest duration of operation. The Yoon-Nelson model was employed to predict the half-saturation times of all adsorbents. The adsorbents were tested for regeneration. PFA300 and XAD4 yielded high regeneration percentages. Based on the results, PFA300 was the most effective material for removing PFOA in water and wastewater because it exhibited the highest adsorption capacity, the longest duration of operation, and the highest PFOA recovery percentage.

Perfluorooctane sulfonate (PFOS) has been detected widely in the natural water matrix and is persistent, bioaccumulative, and toxic. To prevent the adverse effects of PFOS contamination on human health and the environment, effective removal techniques are needed. Adsorption is considered an effective technique for PFOS removal. In this study, five anion exchange resins and granular activated carbon (GAC) were examined to evaluate their performance for the removal of PFOS in both batch and column experiments. Experimental adsorption data for all of the adsorbents exhibited a high correlation with the Freundlich isotherm (R 2 5 0.95 -0.98). Most of the anion exchange resins demonstrated a higher adsorption capacity than the GAC. PFA300 had the highest adsorption capacity (455 mg/g). Continuous adsorption of PFOS was performed in column experiments using the same adsorbents that had been used in the batch experiments. The experimental breakthrough curves were set at C/C 0 5 0.1. PFA300 showed the longest operation time before reaching the breakthrough point. The Yoon and Nelson model was used to predict the half-saturation time of the anion exchange resins. Moreover, the anion exchange resins exhibited high recovery of PFOS by an organic solvent. Continuous PFOS adsorption on a column can be achieved using anion exchange resins for water/wastewater treatment.

Perfluorohexanoic acid (PFHxA) is increasingly used in industries and widely detected in water environment. Conventional wastewater treatment plants are ineffective to treat PFHxA. Therefore, effective removal techniques are required to minimize health risks and environmental impacts. In this study, adsorption capacities of PFHxA onto three strong base anion exchange polymers (PFA300, PFA400 and A860), two weak base anion exchange polymers (BA103 and MN102), non-ion exchange polymers (XAD4) and granular activated carbon (GAC) were studied by batch experiments. Effects of chloride, sulfate and nitrate ions on the PFHxA adsorption were investigated for all adsorbents. The Freundlich equation was fitted with the equilibrium adsorption data. BA103 exhibited the highest adsorption capacity (412 mg/g) because it had the highest exchange capacity. Amounts of PFHxA adsorbed onto adsorbents decreased when chloride, sulfate and nitrate ions increased in the solution. Nitrate ion had more effects on the adsorption capacities of PFHxA than sulfate and chloride ions. BA103 had the highest adsorption capacity of PFHxA in presence of chloride, sulfate and nitrate ions. BA103 showed as an effective adsorbent to remove PFHxA in water/ wastewater.

PFCs) are synthetic chemical which is persistent, bio-accumulative and suspected to be toxic. Municipal wastewater treatment plants (MWWTPs) have been identified as sources of PFCs contamination in water environment. This study focused on the contamination of eleven PFCs in samples collected from seven MWWTPs and in Bangkok, Thailand. The samples were collected from major of wastewater treatment processes in order to understand the behavior of PFCs in MWWTPs. All MWWTPs used activated sludge process to treat wastewater. The result showed that Chong Nonsi MWWTPs had the highest of PFCs concentration in final effluent (63.6 ng/L). Perfluorootane sulfonate (PFOS) and perfluorootanoic acid (PFOA) were predominant PFCs detected in final effluents than other PFCs. Final effluents had higher PFCs concentration than influents of the MWWTP which indicated that conventional wastewater treatment process using activated sludge was not effective to remove PFCs. Long carbon-chain PFCs tended to adsorb on particulate phase more than short carbon-chain ones. Comparing to other countries, the effluent concentration levels of PFOS and PFOA in Thailand were lower than those in Denmark, Taiwan and Singapore. However, several PFCs were detected in MWWTPs, suggesting municipal wastewater is one of the sources of PFCs contamination in the environment.