Superhydrophobic-Activated Carbon Coating: A Path toward Demulsification and Separation of Crude Oil Emulsions

The emissions of oily wastewater represent a considerable risk to the environment. The demulsification and separation of crude oil emulsions have been difficult problems in the field of petroleum. Consequently, the development of green, cost-effective, and highly efficient demulsification and/or oil-water separation technologies has emerged as a critical research priority. In this study, activated carbon (AC) was designed to be modified by using hexadecyltrimethoxysilane (HDTMS) as a superhydrophobic material. By spraying a mixture of the superhydrophobic AC and epoxy resin onto 300# and 2000# stainless steel mesh (SSW), superhydrophobic AC-coated SSWs with excellent wetting resistance and durability were developed. These superhydrophobic AC-coated SSWs completely replaced demulsifiers for achieving the separation of crude oil emulsions. The 300# AC-coated SSW demonstrated a remarkable separation efficiency above 96.6% across five types of oil-water mixtures. For chloroform-water mixtures, the separation efficiency and flux consistently remained above 97.7% and 12050 L·m^-2·h^-1 over 20 consecutive separation cycles. The 2000# AC-coated SSW also demonstrated stable separation efficiency and flux of 94.8% and 490.8 L·m^-2·h^-1 for the separation of water-in-chlorobenzene (W/O) emulsions after 20 consecutive cycles. This underscores the material's consistent high performance in oil/water separation processes. The strategy of the separation materials may provide a general hydrophilic modification method for a new generation of high-performance superhydrophobic activated carbon coatings and offers a prospective technical support for the efficient and rapid separation and purification of oily wastewater.