Construction of a Mercapto-Functionalized Zr-MOF/Melamine Sponge Composite for the Efficient Removal of Oils and Heavy Metal Ions from Water

The treatment of multicontaminant wastewater has attracted extensive attention in recent years. Herein, we synthesized a porous and hydrophobic composite (Zr-MOF-SH/MF) via the in situ growth of mercapto-functionalized Zr-metal–organic frameworks (MOFs) (Zr-MOF-SH) on the surface of a melamine formaldehyde (MF) sponge. The successful growth of hydrophobic Zr-MOF-SH, as confirmed by SEM, XRD, and XPS analysis, made the MF sponge become hydrophobic with a water contact angle of 125°. The adsorption capacity of the Zr-MOF-SH/MF composite for dichloromethane can reach up to 113 g/g. Moreover, the composite can efficiently and selectively remove Hg2+ ions from water. Especially, PCN-224-MAA/MF had an adsorption capacity of 412.5 mg/g for Hg2+ ions. The removal efficiency of Hg2+ ions increased as the oil content in the oil–water mixture increased. In addition, PCN-224-MAA/MF can be recovered and reused five times with only a slight decrease in adsorption capacity. This study provides a promising strategy for the synthesis of a dual-functional composite that exhibits excellent performance in removing oil and heavy metal ions simultaneously from water.