Structure–activity relationship and application advancement strategy of Prussian blue for removing Cs/Tl ions in aqueous phase: A critical review

Prussian blue(PB)and its analogues (PBAs), a class of metal-organic framework (MOF) materials with well-defined lattice structures, have been recognized as advanced adsorbents for Thallium/Cesium remediation. This recognition stems from their high adsorption capacity, excellent selectivity, and environmental friendliness. However, PB & PBAs encounter critical challenges in practical water treatment applications, including unclear adsorption mechanisms, ambiguous structure-activity relationships, and unsystematic elucidation of multiscale mass transfer-adsorption synergistic effects. These issues hinder their transfer from laboratory research to engineering-scale applications. From the perspective of structure-activity relationship, this review systematically clarifies the influences of five critical factors – crystalline phase, node metal ions, guest metal ions, structural waters, and structural defects - those regulate the Cs⁺/Tl⁺ adsorption capacity and mechanisms of PB materials. It specifically investigates the structural response of PB & PBAs and the ion transfer process during the adsorption reaction in aqueous media. The core discussion in this review focuses on the following four aspects: (1) Structural characteristics and regulatory factors of PB & PBAs; (2) Adsorption mechanism for Cs/Tl removal; (3) Structure-activity relationships linking microscopic structures and macroscopic adsorption performances; (4) Design strategies for PB-based composite materials.