Multifunctional Fe₃O₄/TiO₂/NH₂–UiO–66 with integrated interfacial features for favorable phosphate adsorption

Abstract

Excessive use and discharge of phosphate are the decisive factors leading to water eutrophication, and adsorption is deemed among the most effective methods in phosphorus capture. This study prepared the...

Anchoring NH2-MIL-101(Fe/Ce) within Melamine Sponge Boosts Rapid Adsorption and Recovery of Phosphate from Water

“…Nevertheless, the adsorption isotherms of MIL-101@CS and MIL-101@PVDF fit slightly better with the Langmuir model as indicated by the higher R 2 as compared to the Freundlich model (Table S3), indicating that the P adsorption process is likely to stem from a chemisorption in a monolayer manner . Considering the above observations of the uniform distribution of MIL-101 particles within MS scaffolds, it is rational to speculate the formation of monolayer adsorption between the P species and the active adsorption sites, in particular, of MIL-101@CS and MIL-101@PVDF. ,, The isotherm of P adsorption over MIL-101@SDBS exhibits a higher correlation coefficient for Freundlich rather than Langmuir, suggesting that P adsorption over such adsorbent appears to occur in a different manner rather than monolayer. , The maximum P adsorption capacities ( Q m ) calculated by using the Langmuir model are 253.66, 90.84, 104.80, and 17.32 mg g –1 for MIL-101@CS, MIL-101@SDBS, MIL-101@PVDF, and the pristine MS, respectively. Theoretically, the maximum P adsorption capacity of the pristine MS scaffold is markedly increased by approximately 15 times by anchoring MIL-101 within such a scaffold with the aid of a CS binder, validating the feasibility and merits of this integrating strategy.…”

“…This improved adsorption affinity by amine groups was further verified in a study assessing the effect of various functional groups on the adsorption performance of UiO-66 . Other approaches such as doping by specific P-preferring elements, ,,, microstructural tailoring (e.g., creating defect-rich MOFs), ,− and integrating with various compounds, ,− have been successfully implemented. However, these nano- and micro-sized MOF adsorbents often suffer from being difficult to fully recover after dispersing in water and are susceptible to lose during the solid–liquid separation process despite their much higher adsorption affinity compared to conventional monolith adsorbents. , …”

“…18 Considering the above observations of the uniform distribution of MIL-101 particles within MS scaffolds, it is rational to speculate the formation of monolayer adsorption between the P species and the active adsorption sites, in particular, of MIL-101@CS and MIL-101@ PVDF. 27,54,56 The isotherm of P adsorption over MIL-101@ SDBS exhibits a higher correlation coefficient for Freundlich rather than Langmuir, suggesting that P adsorption over such adsorbent appears to occur in a different manner rather than monolayer. 9,18 The maximum P adsorption capacities (Q m ) calculated by using the Langmuir model are 253.66, 90.84, 104.80, and 17.32 mg g −1 for MIL-101@CS, MIL-101@SDBS, MIL-101@PVDF, and the pristine MS, respectively.…”

Defective UiO-66-NH2 (Zr) for Simultaneous Adsorption of Phosphate and Pb2+ for Hydrogen Peroxide Purification

“…The results show that in the acidic environment (pH = 1–3) of hydrogen peroxide, the surface of the adsorbent is positively charged . Therefore, during the adsorption process, there is electrostatic adsorption to phosphate and electrostatic repulsion to Pb 2+ . ,− This suggests the existence of other adsorption mechanisms for Pb 2+ adsorption in hydrogen peroxide solutions.…”

“…Based on the aforementioned analysis, the potential coadsorption mechanisms (Scheme ) of De-UiO-66-NH 2 for phosphate and Pb 2+ are proposed as follows: In the synthesis process of De-UiO-66-NH 2 , the addition of acetic acid replaces some organic ligands by coordinating with metal clusters, introducing more crystal structure defects and exposing additional Zr–OH active sites for the adsorption of phosphate and Pb 2+ . During the adsorption process, phosphate engages in ligand exchange with hydroxyl groups on Zr–OH, producing Zr–O–P, which is anchored to the MOF . Pb 2+ undergoes proton exchange, displacing H + from Zr–OH to form Zr–O–Pb, and achieving effective adsorption.…”