Synthesis of Magnetic Bimetallic Hydroxide Nanosheets for the Clean‐Up of Oily Wastewater

Abstract Mg/Fe‐based magnetic bimetallic hydroxide nanosheets (MHNs) are synthesized by a simple molten salt method (MSM) in 1 min. The surface of the MHNs readily became hydrophobic following octadecyltrimethoxysilane treatment; the hydrophobic MHNs (HMHNs) are then coated onto a Cu mesh and a melamine (MF) sponge by the dip‐coating method for use in oil/water separation. The separation efficiencies of both the HMHN‐coated Cu mesh and MF sponge are greater than 99% for all types of oils, and these samples has significant fluxes and absorption capacities. The HMHN‐coated Cu mesh show outstanding reusability and chemical durability in harsh environments, such as acidic, alkaline and saline solutions, and exhibit excellent oil separation efficiencies for water‐in‐oil emulsions. Moreover, the HMHN powder itself quickly absorb highly viscous oil spills floating on the surfaces of both water and oil stabilized in water, and it can be easily recovered with an external magnet. Due to the economical synthetic process and the variety of techniques applicable to selective oil separation, these MHNs show great potential in the field of oily wastewater treatment.