Extremely Effective Boron Removal from Water by Stable Metal Organic Framework ZIF-67

The development of adsorbents with high adsorption capacity is a great challenge. The ZIF-67 nanocrystal prepared was applied to boron removal for the first time. The results indicated that well-defined rhombic dodecahedral cobalt-based ZIF-67 synthesized at room temperature exhibited good stability. Under pH of 4 and temperature of 25 °C, ZIF-67 exhibited an extraordinarily high boron adsorption capacity of 579.80 mg·g–1 at initial boron concentration of 0.5 mol·L–1, the highest boron adsorption capacity ever reported. The intraparticle diffusion and the film diffusion both were the rate controlling steps. The adsorption of boron to ZIF-67 was mainly due to electrostatic interaction, π–π stacking interaction and the coordination bonding and the boric acid molecules successfully crystallized on the ZIF-67 surface. At the fifth cycle the adsorption capacity of ZIF-67 exhibited 94.1% of the first cycle. ZIF-67 is a promising sorbent for boron removal.