Preparation and characterization of merlinoite for potassium extraction from seawater

The preparation of zeolites for potassium extraction was extensively investigated by hydrothermal method without organic template. The K+ ion-exchange capacities of synthetic zeolites in seawater were tested. Merlinoite with high ion-exchange capacity was successfully synthesized in the synthesis gel with the molar composition of 15K2O:12SiO2:Al2O3:570H2O. The K+ ion-exchange capacity of merlinoite is 58.7 mg/g in seawater, and therefore it can be used to extract potassium selectively from seawater. Merlinoite was characterized by X-ray diffraction, scanning electron microscopy and energy dispersion spectroscopy. Merlinoite crystal which is mainly composed of Si, Al, K and O exhibits a square pillar shape.