This　study　aims　to　investigate　Cs　removal　by　different　external　metals　hexacyanoferrates　MII–Fe　PBA　(MII:　Co,　Ni　and　Cu).　Three　PBAs　were　synthesized,　characterized　and　followed　by　batch　experiment　testing　and　model　fitting.　Among　the　three　PBAs,　Cu–Fe　PBA　possessed　the　highest　capacity　234.28 mg g−1,　the　highest　Kd　2.8　×　106 mL g−1　and　the　fastest　adsorption　kinetics　on　Cs　removal.　Moreover,　Cu–Fe　PBA　and　Ni–Fe　PBA　were　the　more　selective　sorbents　in　coexisting　ions　study.　Finally,　the　adsorption　mechanism　was　proposed.　This　study　provides　new　insights　into　the　vacancies　effect　of　the　PBA　structure　and　Cs　adsorption　application.　©　2023,　Akadémiai　Kiadó,　Budapest,　Hungary.