Constructing superwetting membranes by sodium lignosulfonate-modified carbon nanotube for highly efficient crude oil-in-water emulsions separations

Abstract

For the past few years, superwetting materials had been developed to enhance the treatment process of oily wastewater. Membranes are improved through the combination of surface topography and chemical modifications to achieve superwetting properties for treating oily wastewater effectively. In this work, we prepared an eco-friendly membrane by depositing sodium lignosulfonate (SLS)-modified carbon nanotube (CNT) on a cellulose acetate membrane via vacuum filtration without employing any organic solvents. The SLS@CNT membrane shows superhydrophilicity and underwater superoleophobicity with high stability. Furthermore, the SLS@CNT membrane exhibits outstanding antifouling and self-cleaning properties against crude oil of high viscosity. Most importantly, our SLS@CNT membrane exhibits outstanding oil-in-water emulsions separation performances including crude oil-in-water emulsions. For the surfactant-free and surfactant-stabilized emulsions, fluxes were revealed to reach up to 27,800 L m−2 h−1 bar−1 and 13,800 L m−2 h−1 bar−1, respectively, with very high separation efficiency (>99.97 % and 99.79 %, respectively). The distinguished performance of our SLS@CNT membrane, and its eco-friendly, low-energy consumption, and cost-effective preparation, demonstrate practical applicability.