TY - JOUR
T1 - The adsorption mechanisms of organic micropollutants on high-silica zeolites causing S-shaped adsorption isotherms
T2 - An experimental and Monte Carlo simulation study
AU - Jiang, Nan
AU - Erdös, Mate
AU - Moultos, Othon
AU - Shang, Ran
AU - Vlugt, Thijs J.H.
AU - Heijman, Sebastiaan G.J.
AU - Rietveld, Luuk C.
PY - 2020
Y1 - 2020
N2 - The adsorption of organic micropollutants (OMPs) on high-silica zeolites is characterized by adsorption isotherms with various shapes. The occurrence of an S-shaped adsorption isotherm indicates the lack of adsorption affinity for OMPs at low, environmentally relevant equilibrium concentrations. In this study, S-shaped isotherms were observed during batch experiments with 2,4,6-trichlorophenol (TCP) and FAU zeolites. This is the first time that an S-shaped isotherm is reported for the adsorption of OMPs on high-silica zeolites. Monte Carlo (MC) simulations in the grand-canonical ensemble were used to obtain a better understanding of the mechanism of the S-shaped adsorption isotherms. From the MC simulation results, it was observed that multiple TCP molecules were adsorbed in the supercages of the FAU zeolites. It was found that the π-π interactions between TCP molecules give rise to the adsorption of multiple TCP molecules per supercage, and thus causing an S-shaped adsorption isotherm. Simulations also revealed that water molecules were preferentially adsorbed in the supercages and sodalite cages of the FAU zeolites. FAU zeolites with a higher Al content adsorbed a higher amount of water molecules and a lower amount of TCP, and showed less pronounced S-shaped isotherms.
AB - The adsorption of organic micropollutants (OMPs) on high-silica zeolites is characterized by adsorption isotherms with various shapes. The occurrence of an S-shaped adsorption isotherm indicates the lack of adsorption affinity for OMPs at low, environmentally relevant equilibrium concentrations. In this study, S-shaped isotherms were observed during batch experiments with 2,4,6-trichlorophenol (TCP) and FAU zeolites. This is the first time that an S-shaped isotherm is reported for the adsorption of OMPs on high-silica zeolites. Monte Carlo (MC) simulations in the grand-canonical ensemble were used to obtain a better understanding of the mechanism of the S-shaped adsorption isotherms. From the MC simulation results, it was observed that multiple TCP molecules were adsorbed in the supercages of the FAU zeolites. It was found that the π-π interactions between TCP molecules give rise to the adsorption of multiple TCP molecules per supercage, and thus causing an S-shaped adsorption isotherm. Simulations also revealed that water molecules were preferentially adsorbed in the supercages and sodalite cages of the FAU zeolites. FAU zeolites with a higher Al content adsorbed a higher amount of water molecules and a lower amount of TCP, and showed less pronounced S-shaped isotherms.
KW - High-silica zeolites
KW - Monte Carlo simulation
KW - Organic micropollutants
KW - S-shaped adsorption isotherms
UR - http://www.scopus.com/inward/record.url?scp=85079603243&partnerID=8YFLogxK
U2 - 10.1016/j.cej.2019.123968
DO - 10.1016/j.cej.2019.123968
M3 - Article
SN - 1385-8947
VL - 389
SP - 1
EP - 9
JO - Chemical Engineering Journal
JF - Chemical Engineering Journal
M1 - 123968
ER -