Phosphorus-Enhanced and Calcium-Retarded Transport of Ferrihydrite Colloid: Mechanism of Electrostatic Potential Changes Regulated via Adsorption Speciation

Abstract

The transport of ferrihydrite colloid (FHC) through porous media is influenced by anions (e.g., PO 4 3− ) and cations (e.g., Ca 2+ ) 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 Ca 5 (PO 4 ) 3 OH 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) 2 PO 2 Ca). 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.

Physicomechanical, Wettability, Corrosion, Thermal, and Microstructural Morphology Characteristics of Carbonized and Uncarbonized Bagasse Ash Waste-Reinforced Al-0.45Mg-0.35Fe-0.25Si-Based Composites: Fabrications and Characterizations

“…As a result, there are fewer localized stress concentrations and a more even distribution of mechanical stresses. , The microstructure of the AA6063/3.75 wt % carbonized WBA composites, as demonstrated by SEM analysis, can exhibit how the carbonized WBA is distributed within the AA6063 matrix. Better mechanical characteristics may result from a uniformly distributed hard-phase distribution that is well-dispersed. , …”

“…Better mechanical characteristics may result from a uniformly distributed hard-phase distribution that is well-dispersed. 27,28 In addition, as revealed from Figure 8a,b, the interface among the AA6063 matrix and WBA reinforcement is a crucial area where various interactions occur in Al/carbonized WBA composite MMCs. The interface reaction layer, which is a different region developed by interactions among the Al6063 alloy and WBA particles, is evident in the SEM images.…”

Integrated Assessment and Geostatistical Evaluation of Groundwater Quality through Water Quality Indices

“…Class fair (65-79) covers 62.5% of the entire region, while a small portion is 2.5% of the class (95-100) [64].…”

Enhanced Oxidation of Organic Compounds by the Ferrihydrite–Ferrate System: The Role of Intramolecular Electron Transfer and Intermediate Iron Species

“…Iron oxides, such as ferrihydrite, goethite, and hematite, are ubiquitous in aquatic and most terrestrial environments and participate in various chemical processes. − Ferrihydrite (Fh), characterized by its extensive surface area and unique structure, is particularly reactive and plays a crucial role in regulating the (im)­mobilization contaminants. , On one hand, Fh can contribute to controlling the fate of toxic metals and metalloids by processes such as adsorption/desorption, coprecipitation, and crystallization. − On the other hand, Fh is often utilized as a heterogeneous catalyst to activate H 2 O 2 or persulfate, leading to the degradation of organic contaminants by generating · OH or SO 4 · – . − However, the oxidation of organic contaminants via the combination of Fe­(VI) and Fh remains unexplored.…”

“…25−27 Ferrihydrite (Fh), characterized by its extensive surface area and unique structure, is particularly reactive and plays a crucial role in regulating the (im)mobilization contaminants. 28,29 On one hand, Fh can contribute to controlling the fate of toxic metals and metalloids by processes such as adsorption/desorption, coprecipitation, and crystallization. 30−33 On the other hand, Fh is often utilized as a heterogeneous catalyst to activate H 2 O 2 or persulfate, leading to the degradation of organic contaminants by generating • OH or SO 4…”