Magnetic chitosan-based aerogel decorated with polydimethylsiloxane: A high-performance scavenger for oil in water

Most ingredients used to construct porous substrate of hydrophobic magnetic absorbent for oil/water separation are toxic, environmentally incompatible and difficult to degrade. With the purpose of solving this problem, a magnetic chitosan (CS)-based aerogel decorated with polydimethylsiloxane (PDMS) was successfully fabricated in this work. The magnetic porous substrate was built by the electrostatic interactions between CS, itaconic acid and Fe 3 O 4 nanoparticles (FeNPs) in water solution, followed by a freeze-drying process. The hydrophobic properties were rendered to the substrate by the crosslinking reaction of PDMS. Owing to the low density (0.0655 g/cm 3 ) and high porosity (92%), the prepared aerogel displayed high absorption capacities (8.89–22.38 g/g) towards the testing organic liquids. The silylation process provided the aerogel with excellent hydrophobic properties (water contact angle, 147.1°), resulting in selectively absorbing oil from immiscible oil/water mixture and water-in-oil emulsion. Due to the uniformly distributed FeNPs, the remote control of the aerogel by external magnetic field was acquired, the saturation magnetization of which was 11.22 emu/g. Furthermore, the aerogel could also continuously separate heavy oil from water by acting as filter. The experimental results indicate that this renewable, environmentally benign and bifunctional aerogel has great potential in oily wastewater remediation.