Fabrication of highly hydrophobic sand@soot with core–shell structure and large-scale production possibility for oil/water separation

One of the ever increasing environmental concerns for marine areas is oil spillage, and seeking a suitable method for the separation of oil spills from water is of vital importance. Here, highly hydrophobic sand as a very low-cost material has been synthesized for oil/water separation. By kerosene combustion using a burner, nano/micro-soot can be easily coated on the surface of sand. By this one-step method, highly hydrophobic sand with a water contact angle of 134 ± 5° has been obtained. The prepared hydrophobic sand covered with soot has been fully characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Hydrophobic core–shell sand@soot has been used as a filter that allows the passage of oil, but prevents the infiltration of water. The time consumption for oil/water separation is low and the separation system does not need any special force. A continuous separation system based on simple equipment has been designed for the removal of oil from the surface of water with high efficiency. Due to the abundance of the precursor materials, the simplicity of the synthesis process, and the feasibility of large-scale production, the prepared hydrophobic sand@soot can be regarded as a suitable material for oil/water separation in real systems.