Metastable Zirconium Phosphate under Nanoconfinement with Superior Adsorption Capability for Water Treatment

Abstract

In confined space with length scale of several nanometers, the phase behavior of matter, e.g., nucleation and crystallization, is completely different from its analogue in bulk. However, in environmental applications, the relationship between the nanoconfined crystallization behavior of inorganic crystals and their properties for pollutant removal is rarely elucidated. Herein, an unusual formation of zirconium phosphate (ZrP) crystals as a mixture of both thermodynamically stable α‐ and metastable γ‐phases inside the nanoconfinement of 7.9 nm pores of mesoporous polystyrene (MPS) is reported. This consequently changes the interaction between ZrP and toxic metal cations from nonspecific electrostatic attraction of normal α‐ZrP to highly specific inner‐sphere coordination of nanoconfined γ‐ZrP, which exhibits remarkable reactivity as well as reusability for the removal of toxic metals. The results of this study contribute to a better understanding of the use of nanoconfinement for the regulation of material properties.

Treatment of Wastewaters with Zirconium Phosphate Based Materials: A Review on Efficient Systems for the Removal of Heavy Metal and Dye Water Pollutants

“…A mesoporous polystyrene (MPS) matrix was also used to immobilize ZrP [ 60 ]. According to this procedure, the MPS host was first prepared by a flash freezing method, which allowed the acquisition of spherical beads of 1.5–2.0 mm in diameter, with abundant uniform pores of around 7.9 nm.…”

Revisiting the Old and Golden Inorganic Material, Zirconium Phosphate: Synthesis, Intercalation, Surface Functionalization, and Metal Ion Uptake

“…246,266−268 Zhang et al in 2020 reported the synthesis of mixed-phase, thermodynamically stable α-ZrP and metastable γ-ZrP encapsulated within 7.9 nm mesopores created by mesoporous polystyrene (MPS). 246 The nanoconfinement offered by MPS alters the interaction between ZrP and Pb(II) ions from nonspecific electrostatic attraction to specific inner-sphere coordination as shown in Figure 21c. The nanocomposite, ZrP@ MPS surprisingly shows high adsorption capacity and selectivity with K d values 10−90 times higher than for nonconfined α-ZrP.…”

“…(C) Schematic illustration of lead ion adsorption by the ZrP formed inside (a) confined space and (b) the α-ZrP. Reproduced with permission from ref . Copyright 2020 Wiley-VCH.…”

Science and Technology Roadmap for Adsorption of Metallic Contaminants from Aqueous Effluents Using Biopolymers and Its’ Derivatives

“…Moreover, surface functionality enhances the hydrophilicity of the polymer composite and hence improves the heavy metal removal. For instance, a published study found that the adsorption of mesoporous polystyrene for metal ions can be enhanced using zirconium phosphate (ZrP) in nanoconfinement (Zhang et al 2020).…”