Template-Free Synthesis of KCHA Zeolite for Sustainable Potassium Extraction

The performance of potassium chabazite (KCHA) zeolite in potassium extraction from seawater and sea bittern at room temperature was systematically investigated for the first time. EDS analysis revealed that sample S2 exhibited a peak potassium content of 20.0 wt.% at a Si/Al molar ratio of 1.39. XRD characterization confirmed that sample S2 was KCHA zeolite, while its morphology showed a walnut-shaped structure with high symmetry. CO₂ adsorption experiments indicated that the main pore width of KCHA zeolite ranged from 0.50 to 0.55 nm. At room temperature, KCHA demonstrated potassium ion exchange capacities of 36 mg/g in seawater and 80 mg/g in sea bittern. The ion exchange between ammonium and potassium ions in KCHA zeolite occurred rapidly. KCHA zeolite showed excellent reusability for potassium extraction. Notably, KCHA zeolite exhibited a unique potassium ion memory effect, highlighting its special adsorption properties.