Adsorption behavior of per- and polyfluoralkyl substances (PFASs) to 44 inorganic and organic sorbents and use of dyes as proxies for PFAS sorption

In situ gas sparging for concentration and removal of per‐ and polyfluoroalkyl substances (PFAS) from groundwater

“…PFAS chemicals are difficult and expensive to analyze; therefore, a commonly available surfactant (Persil detergent) was dyed with Methylene Blue to illustrate the effect of air sparging in the column. This product was selected because it was inexpensive and easy to handle from a health perspective rather than having certain properties that approximated a particular PFAS (methylene blue has also been proposed as a surrogate for PFAS laboratory experiments as well (Sörengård et al, 2020). Air sparging F I G U R E 3 Six-hour long laboratory experiment using air sparging to concentrate dyed surfactant in top portion of laboratory column.…”

Reply to Comment on “Highly Selective Removal of Perfluorinated Contaminants by Adsorption on All‐Silica Zeolite Beta”

“…For all‐silica Beta, a detailed study of the distribution constants K d (L kg −1 ) at low concentration and adsorbent loading is ongoing, but preliminary results show that for example, for PFOA, log K d >5, [7] which is better than all standard carbons and zeolites reported by Ahrens et al. in their comparative study of 44 solid commercial adsorbents for PFAS removal [4] . More importantly, our study yields important structure‐performance relationships through which zeolites, an important class of adsorbents, can be designed for the selective adsorption of PFAS.…”

Reply to Comment on “Highly Selective Removal of Perfluorinated Contaminants by Adsorption on All‐Silica Zeolite Beta”

“…Activated carbon (AC) adsorbents have been widely studied for perfluorinated acids by the scientific community since a decade, and we therefore used a powdered activated carbon as a benchmark [3, 4] . An ideal adsorbent would combine at least (1) a high capacity, (2) a high affinity, (3) a preserved performance in the presence of low‐molecular organic competitors, and (4) a high stability to diverse regeneration treatments.…”

“…[2] Activated carbon (AC) adsorbents have been widely studied for perfluorinated acids by the scientific community since ad ecade,a nd we therefore used ap owdered activated carbon as ab enchmark. [3,4] An ideal adsorbent would combine at least (1) ah igh capacity,( 2) ah igh affinity,( 3) a preserved performance in the presence of low-molecular organic competitors,a nd (4) ah igh stability to diverse regeneration treatments.A ll-silica Beta reaches am aximum capacity of > 37 wt.% PFOA, corresponding to ac omplete filling of the micropore volume.S aturation capacities of diverse carbon types are generally 20 wt. %.…”

“…[6] Forall-silica Beta, adetailed study of the distribution constants K d (L kg À1 )a tl ow concentration and adsorbent loading is ongoing, but preliminary results show that for example,for PFOA, logK d > 5, [7] which is better than all standard carbons and zeolites reported by Ahrens et al in their comparative study of 44 solid commercial adsorbents for PFAS removal. [4] More importantly,o ur study yields important structure-performance relationships through which zeo-lites,animportant class of adsorbents,can be designed for the selective adsorption of PFAS.…”