TY - JOUR
T1 - Phosphorus-Enhanced and Calcium-Retarded Transport of Ferrihydrite Colloid
T2 - Mechanism of Electrostatic Potential Changes Regulated via Adsorption Speciation
AU - Ma, Jie
AU - Li, Jinbo
AU - Weng, Liping
AU - Ouyang, Xiaoxue
AU - Chen, Yali
AU - Li, Yongtao
PY - 2023/2/27
Y1 - 2023/2/27
N2 - The transport of ferrihydrite colloid (FHC) through porous media is influenced by anions (e.g., PO43-) and cations (e.g., Ca2+) in the aqueous environment. This study investigated the cotransport of FHC with P and P/Ca in saturated sand columns. The results showed that P adsorption enhanced FHC transport, whereas Ca loaded onto P-FHC retarded FHC transport. Phosphate adsorption provided a negative potential on the FHC, while Ca added to P-FHC led to electrostatic screening, compression of the electric double layer, and formation of Ca5(PO4)3OH followed by heteroaggregation at pH ≥ 6.0. The monodentate and bidentate P surface complexes coexisted, and Ca mainly formed a ternary complex with bidentate P (≡(FeO)2PO2Ca). The unprotonation bidentate P at the Stern 1-plane had a considerable negative potential at the Van der Waals molecular surface. Extending the potential effect to the outer layer of FHC, the potential at the Stern 2-plane and zeta potential exhibited a corresponding change, resulting in a change in FHC mobility, which was validated by comparison of experimental results, DFT calculations, and CD-MUSIC models. Our results highlighted the influence of P and Ca on FHC transport and elucidated their interaction mechanisms based on quantum chemistry and colloidal chemical interface reactions.
AB - The transport of ferrihydrite colloid (FHC) through porous media is influenced by anions (e.g., PO43-) and cations (e.g., Ca2+) in the aqueous environment. This study investigated the cotransport of FHC with P and P/Ca in saturated sand columns. The results showed that P adsorption enhanced FHC transport, whereas Ca loaded onto P-FHC retarded FHC transport. Phosphate adsorption provided a negative potential on the FHC, while Ca added to P-FHC led to electrostatic screening, compression of the electric double layer, and formation of Ca5(PO4)3OH followed by heteroaggregation at pH ≥ 6.0. The monodentate and bidentate P surface complexes coexisted, and Ca mainly formed a ternary complex with bidentate P (≡(FeO)2PO2Ca). The unprotonation bidentate P at the Stern 1-plane had a considerable negative potential at the Van der Waals molecular surface. Extending the potential effect to the outer layer of FHC, the potential at the Stern 2-plane and zeta potential exhibited a corresponding change, resulting in a change in FHC mobility, which was validated by comparison of experimental results, DFT calculations, and CD-MUSIC models. Our results highlighted the influence of P and Ca on FHC transport and elucidated their interaction mechanisms based on quantum chemistry and colloidal chemical interface reactions.
KW - calcium
KW - CD-MUSIC
KW - DFT calculation
KW - ferrihydrite colloids
KW - phosphorus
KW - transport
U2 - 10.1021/acs.est.2c09670
DO - 10.1021/acs.est.2c09670
M3 - Article
C2 - 36848599
AN - SCOPUS:85149150845
SN - 0013-936X
VL - 57
SP - 4219
EP - 4230
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 10
ER -