Preparation of novel functional MER zeolite membrane for potassium continuous extraction from seawater

Merlinoite(MER) zeolite membranes were synthesized on the outer surface of porous α-alumina tubular support by in-situ hydrothermal synthesis method without organic template. The synthetic MER zeolite membranes (sample 1, sample 2 and sample 3) were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). The thickness of sample 2 without cracks is about 15 μm. The synthetic MER membrane which is mainly composed of Si, Al, O and K is typical merlinoite structure. The performance of sample 2 for potassium extraction in simulated seawater was researched by the membrane tube reactor. The continual ion-exchange reaction was carried out for 108 h at room temperature. The average exchange rate for K+ ion was 32.8% and the average rejection rates for Na+, Ca2+ and Mg2+ ions were 93.4, 98.4 and 98.2% respectively. So the MER zeolite membrane (sample 2) has preference selectivity for K+ ion and can be used as a potential inorganic membrane for potassium extraction from seawater.