Efficient oil/water separation using grass-like nano-cobalt oxide bioinspired dual-structured coated mesh filters

Superhydrophobic bioinspired grass-like nano-cobalt oxide mesh filters, fabricated by a sequential hydrothermal method , were applied successfully for the oil-water separation process. The micro/nano-hierarchical dual-structured coated meshes exhibited excellent water repellency with a water contact angle (WCA) of 161.9° ± 0.5° and contact angle hysteresis (CAH) of 4.6° ± 0.8° after modification with stearic acid . X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Energy dispersive spectroscopy (EDX), and Fourier transform infrared (FTIR) analyses were applied to characterize the prepared samples. The effect of the coating layers’ variation on the wetting properties, oil flux, and water intrusion pressure was investigated. Oil flux and water intrusion pressure of fabricated mesh filter showed a downward (from 22000 L.m −2 .h −1 to 15000 L.m −2 .h −1 ) and upward (from 6 cm to >10 cm) trend, respectively, with increasing the number of the coating layers. The prepared coated meshes also showed excellent separation efficiency (>98%), good reusability, and good superhydrophobic stability even after ten cycles of sandpaper abrasion . Besides, the prepared filter had better chemical stability in the alkaline media than the acidic ones.