Fabrication of Superhydrophilic-Superoleophobic ZnO Surface to Separate Hydrocarbonic Contamination from Wastewater of Shahid Hasheminejad Gas Processing Company

Decrease in the amount of oil content and total petroleum hydrocarbons (TPH) in the wastewater of petrochemical plants and oil refinery to environmental discharge standard level has been one of the most critical challenges in recent years, requiring new scientific ideas and techniques. In this study, the superhydrophilic ZnO surface was fabricated using a facile and inexpensive coating method on the stainless steel mesh. The prepared surface was characterized using the FESEM, XRD and Raman analyses. The wettability property of the zinc oxide surface was evaluated via the water contact angle and contact angle hysteresis measurements. The FESEM micrograph results show that the coated hierarchical ZnO structure includes two layers of vertically aligned nanorods bottom arrays with a diameter of less than 50 nm and flower-like microstructures at the top composed of ZnO needles with the tip diameter approximately 100 nm. The fabricated surface exhibits superhydrophilc-superoleophobic property with the water contact angle ~ 0° in the air and 161 ± 3° underwater, respectively. This surface also displays excellent performance to separate hydrocarbonic contaminations from wastewater of Shahid Hasheminejad Gas Processing Company with the separation efficiency and permeate water flux of more than 99.9% and 5800 L m-2 h-1, respectively. The average total oil concentration in the effluent sample was significantly reduced from 5000 mg.L-1 to 17.3 mg.L-1. Moreover, the TPH concentration was decreased to 15.5 ppm in the treated effluent. These results show out the great potential of the superhydrophilic ZnO surface for wastewater treatment and offshore oil spills.