Construction of defective zirconium phosphate via nanoconfinement transformation for rubidium adsorption

• A nanoconfinement transformation strategy is proposed to synthesize defective zirconium phosphate. • D-α-ZrP exhibits excellent adsorption capacity for Rb + compared to conventionally synthesized α-ZrP and UiO-66 used as a precursor. • The possible adsorption mechanism for D-α-ZrP toward Rb + is ion exchange between Rb + and H + in Zr–OH and P–OH. Rubidium (Rb) adsorption is vital for environmental conservation and resource recycling. Zirconium phosphate (ZrP), as an excellent ion exchange material, is expected to become the most promising adsorbent for Rb. Herein, a nanoconfinement transformation strategy is proposed to construct defective zirconium phosphate, and an efficient Rb + adsorbent (D-α-ZrP) is prepared. Benefiting from nanoconfinement effect generated by the UiO-66 crystal, the defective structure is formed that rarely occurs in conventional synthesis, which makes D-α-ZrP introduce more adsorption sites (Zr–OH) to increase the adsorption capacity. As expected, D-α-ZrP exhibits excellent adsorption capacity for Rb + compared to conventionally synthesized α-ZrP and UiO-66 used as a precursor. Systematic adsorption experiments demonstrate that the adsorption behavior of Rb + on the D-α-ZrP can be depicted by the Langmuir and pseudo-second-order kinetic models. Moreover, the adsorbent shows great structural stability and good regenerative performance. The mechanism analysis indicates that Zr–OH and P–OH play significant roles in the adsorption process, which is revealed by experimental characterization. Theoretical calculations further demonstrate that Zr–OH exhibits stronger adsorption interactions compared to P–OH. Therefore, this work may provide a theoretical guideline for building novel high-performance adsorbents for metal ions and facilitate insight into the use of nanoconfinement effect to modulate material properties.