Renewable Adsorbent for the Separation of Surfactant-Stabilized Oil in Water Emulsions Based on Nanostructured Sawdust

This work reports the surface modification of sawdust particles with silane-modified alumina nanoparticles and polydimethylsiloxane to create smart micron-sized adsorbents for separation of surfactant-stabilized emulsions. A very fine polysiloxane network (<12 nm) was created on the surface of alumina nanoparticles which were then uniformly coated on the surface of sawdust particles to create a hierarchical film with thickness < 500 nm. The composite particles were then coated with polydimethylsiloxane to create a stable superhydrophobic absorbent with water contact angle > 150° and thermal stability up to 200 °C. The adsorbent is wet by oil and can be used to separate surfactant-stabilized emulsions under mechanical agitation. The adsorbent was able to remove most of the oil content from the emulsions; the optical transmittance of emulations increased from 0 to ca. 90% after separation, and optical microscopy images showed very low traces of oil in the filtrate.