Development of superhydrophobic/superoleophilic cotton micro dust waste functionalized SiO₂ nanocomposite as an efficient adsorbent for oil/water separation

The increasing discharge of oily wastewater from the industries poses a serious threat to human lives and ecological environment. In our present study, we have developed SiO₂ nanoparticle-based cotton micro dust waste for oil removal from water. The SiO₂ nanoparticles and the cotton waste silicon dioxide nanoparticles-nanocomposite (CW-SiO₂-NC) were characterized using UV–visible spectroscopy, particle size analyzer, zeta potential analyzer, transmission electron microscopy (TEM), selected area electron diffraction (SAED), contact angle measurement, X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and Fourier transform infrared spectroscopy (FTIR). The CW-SiO₂-NC showed a superhydrophobicity of 145.8° and superoleophilicity of 3.2°. The amorphous nature of SiO₂ and the presence of SiO₂ nanoparticles in the nanocomposite were confirmed using XRD technique. The nanocomposite has a high mechanical strength as it withstands a force up to 2114.19 N. The nanocomposite has a good thermal stability of about 255.2 °C, which was obtained through thermogravimetric analysis (TGA). The BET analysis showed the surface area was 17.344 m²/g. Oil adsorption was investigated in dip mode method. The adsorption capacity for the developed nanocomposite (CW-SiO₂-NC) was found to be as 3.47 mg/g. Kinetic studies were carried out for the adsorption studies and were found that the nanocomposite follows pseudo-second-order kinetic model. The FTIR analysis confirmed the adsorption of oil molecules onto the developed nanocomposite. Further, field trial was carried out using industrial wastewater sample collected from matured coconut processing industry and tested for oil/fatty content’s removal by dip mode adsorption process using CW-SiO₂-NC. The developed composite showed the oil/fatty content’s removal efficiency of 91.5%. This facile approach of designing nanocomposite is efficient in removing oil/fatty contents from industrial effluents.