TY - JOUR
T1 - Mechanistic understanding of perfluorooctane sulfonate (PFOS) sorption by biochars
AU - Krebsbach, Samuel
AU - He, Jianzhou
AU - Adhikari, Sushil
AU - Olshansky, Yaniv
AU - Feyzbar, Farshad
AU - Davis, Leonard C.
AU - Oh, Tae Sik
AU - Wang, Dengjun
N1 - Publisher Copyright:
© 2023 Elsevier Ltd
PY - 2023/7
Y1 - 2023/7
N2 - Biochar has recently emerged as a cost-effective solution to combat per- and polyfluoroalkyl substances (PFAS) pollution in water, but mechanistic understanding of which physicochemical properties of biochars dictate PFAS sorptive removal from water remains elusive. Herein, 15 biochars were pyrolyzed from five feedstocks (corn, Douglas fir, eucalyptus, poplar, and switchgrass) at three pyrolysis temperatures (500, 700, and 900 °C) to investigate their removal efficiencies and mechanisms of perfluorooctane sulfonate (PFOS) from water. A commercial biochar was also included for comparison. Biochar physiochemical properties, including elemental composition, pH, specific surface area (SSA), pore structure, hydrophobicity, surface charge, surface functional groups, and crystalline structure were systematically characterized. Batch sorption data showed that the Douglas fir 900 biochar (Douglas fir and 900 are the feedstock type and pyrolysis temperature, respectively; this naming rule applies to other biochars), poplar 900 biochar, and commercial biochar can remove over 95% of PFOS from water. Structural equation model (SEM) was used to elucidate which biochar properties affect PFOS sorption. Interestingly, biochar pore diameter was identified as the most critical factor controlling PFOS removal, but pore diameter/pore volume ratio, SSA, pyrolysis temperature, hydrophobicity, and elemental composition all played variable roles. Hypothetically, biochars with small pore diameters and large pore volumes had a narrow yet deep pore structure that traps PFOS molecules inside once already sorbed, resulting in an enhanced PFOS sorption. Biochars with small pore diameter, low nitrogen content, and high pyrolysis temperature were also favorable for enhanced PFOS sorption. Our findings advance the knowledge of using biochars with optimized properties to remove PFOS and possibly other similar PFAS compounds from water.
AB - Biochar has recently emerged as a cost-effective solution to combat per- and polyfluoroalkyl substances (PFAS) pollution in water, but mechanistic understanding of which physicochemical properties of biochars dictate PFAS sorptive removal from water remains elusive. Herein, 15 biochars were pyrolyzed from five feedstocks (corn, Douglas fir, eucalyptus, poplar, and switchgrass) at three pyrolysis temperatures (500, 700, and 900 °C) to investigate their removal efficiencies and mechanisms of perfluorooctane sulfonate (PFOS) from water. A commercial biochar was also included for comparison. Biochar physiochemical properties, including elemental composition, pH, specific surface area (SSA), pore structure, hydrophobicity, surface charge, surface functional groups, and crystalline structure were systematically characterized. Batch sorption data showed that the Douglas fir 900 biochar (Douglas fir and 900 are the feedstock type and pyrolysis temperature, respectively; this naming rule applies to other biochars), poplar 900 biochar, and commercial biochar can remove over 95% of PFOS from water. Structural equation model (SEM) was used to elucidate which biochar properties affect PFOS sorption. Interestingly, biochar pore diameter was identified as the most critical factor controlling PFOS removal, but pore diameter/pore volume ratio, SSA, pyrolysis temperature, hydrophobicity, and elemental composition all played variable roles. Hypothetically, biochars with small pore diameters and large pore volumes had a narrow yet deep pore structure that traps PFOS molecules inside once already sorbed, resulting in an enhanced PFOS sorption. Biochars with small pore diameter, low nitrogen content, and high pyrolysis temperature were also favorable for enhanced PFOS sorption. Our findings advance the knowledge of using biochars with optimized properties to remove PFOS and possibly other similar PFAS compounds from water.
KW - Biochar
KW - Perfluorooctane sulfonate (PFOS)
KW - Physicochemical properties
KW - Sorption
KW - Structural equation model
UR - http://www.scopus.com/inward/record.url?scp=85152743646&partnerID=8YFLogxK
U2 - 10.1016/j.chemosphere.2023.138661
DO - 10.1016/j.chemosphere.2023.138661
M3 - Article
C2 - 37044140
AN - SCOPUS:85152743646
SN - 0045-6535
VL - 330
JO - Chemosphere
JF - Chemosphere
M1 - 138661
ER -