A Novel Vanadosilicate with Hexadeca‐Coordinated Cs + Ions as a Highly Effective Cs + Remover

The effective removal of 137 Cs +  ions from contaminated groundwater and seawater and from radioactive nuclear waste solutions is crucial for public health and for the continuous operation of nuclear power plants. Various 137 Cs +  removers have been developed, but more effective 137 Cs +  removers are still needed. A novel microporous vanadosilicate with mixed‐valence vanadium (V 4+ and V 5+ ) ions is now reported, which shows an excellent ability for Cs +  capture and immobilization from groundwater, seawater, and nuclear waste solutions. This material is superior to other known materials in terms of selectivity, capacity, and kinetics, and at very low Cs +  concentrations, it was found to be the most effective material for the removal of radioactive Cs +  ions under the test conditions. This novel vanadosilicate also contains hexadeca‐coordinated Cs +  ions, which corresponds to the highest coordination number ever described.