Facile preparation of hydrophobic covalent organic polymer-modified melamine sponges for efficient oil–water separation

Oil spills and oily wastewater discharges not only cause serious environmental pollution but also result in great losses to water resources and harm to human health. Thus, there is an urgent need for an efficient and convenient oil–water separation method. In this work, the modified sponge (TFB-MDA@MS) was successfully obtained by grafting a covalent organic polymer (COPs) onto melamine sponge (MS). This composite sponge exhibited good hydrophobicity (the water contact angle in air was 147.7°) and excellent absorption capacity for different kinds of organic solvents (62.59–160.54 g/g), as well as excellent reusability. Furthermore, TFB-MDA@MS demonstrated a good separation effect on oil–water mixtures with a fast absorption speed. It maintained good hydrophobicity and absorption capacity in complex chemical environments (acids, alkalis and salts), and could achieve effective separation of water-in-oil and oil-in-water emulsions. This work presents a method for synthesizing COPs nanoparticle-modified hydrophobic sponges for oily wastewater treatment and the removal of organic pollutants from water surfaces.