Removal of Concentrated PFOS and PFOA in Synthetic Industrial Wastewater by Powder Activated Carbon and Hydrotalcite

Perfluorooctane sulfonate (PFOS) and Perfluorooctano ic acid (PFOA), mainly applied in industries, have silently contaminated the global water sources for many decades. Moreover, high persistent in environment and estrogenic effects on some aquatic animals have been reported in many studies. The failure of conventional wastewater treatment plant indicates need for development of the effective treatment technique for wastewater containing the compounds. However, the previous studies mostly developed treatment at lower compound concentration than industrial wastewater. In this study, compounds removal at the comparatively high concentration with the wastewater was preliminary investigated using six different adsorbents. Among tested adsorbents, Powder activated carbon (PAC) and hydrotalcite provided greater than 97% removal for both compounds and were selected for study of sorption behaviors. Their sorption equilibrium was achieved rapidly in all tests, especially the sorption of PFOS on PAC. For hydrotalcite, equilibrium was achieved within 1 hour. The kinetic study showed higher initial sorption rate (v0) of PFOS than PFOA with both adsorbents. pH was found to affect only the initial sorption rate in all experiments. For isotherm study, Langmuir isotherm was effective in evaluating the sorption of both compounds on PAC. Freundlich isotherm was appropriate with hydrotalcite. The isotherm result clearly reveals different sorption behavior of PAC and hydrotalcite with concentrated compounds.