Construction of PA6-rGO nanofiber membrane via electrospraying combining electrospinning processes for emulsified oily sewage purification

Abstract

• PA6-rGO composites were synthesized through in situ ring-opening polymerization • PA6-rGO membrane was constructed by combining electrospinning and electrospraying • Super hydrophilicity and underwater super oleophobicity were effectively integrated • Stable membranes with good oil droplet rejection were obtained The construction of highly efficient membranes toward oil/water separation is crucial in severe oily sewage treatment while graphene materials are considered stable blocks for oil/water separating membranes. Herein, first, with the presence of graphene oxide, in-situ polymerization of caprolactam was carried out and polyamide-6-reduced graphene oxide composites (PA6-rGO) were successfully synthesized. Then the PA6-rGO nanofiber membranes were prepared by electrospinning combining electrospraying process. Nanofiber skin with microshphere/bead fiber structure on the surface of ordinary electrospun fiber membrane was prepared in 2 steps. Hence the nanofiber membrane separation performance to emulsions under gravity driving was investigated. The results showed that the flux of surfactant-stabilized emulsions would reach up to 765.4 Lm −2 ·h −1 with the rejection up to 99.6%. It is expected to be practically applied in a low-pressure driven membrane separation system to achieve preliminary separation of severe oily sewage.