A rare potassium-rich zirconium fluorophosphonate with high Eu 3+ adsorption capacities from acidic solutions.

A novel 3D potassium-containing zirconium fluorophosphonate K 2 Zr[CH 2 (PO 3 ) 2 ]F 2 (SZ-8) was successfully synthesized as single crystals via a solvothermal method using a mixture of nitric acid and potassium nitrate as mineralizers. SZ-8 can adsorb 110.6 and 57 mg g -1 of Eu 3+ in pH 2 and pH 1 solutions respectively, highlighting its potential remediation for radionuclides with high charges. SZ-8 not only possesses superior Eu 3+ removal capacity under strongly acidic conditions, but also provides a universal synthesis strategy for crystalline zirconium phosphonates with inorganic counterions.