Robust Fe 3 O 4 @attapulgite-intercalated carboxylated graphene oxide composite membrane for efficient and stable oil-in-water emulsion separation

The intercalation of inorganic nanofillers into graphene oxide (GO) layers regulates the pore structure of composite membranes, enhancing their application in oil-in-water (O/W) separation. However, the weak bonding between the nanofillers and GO may compromise membrane stability, affecting separation performance. Herein, we present a method for constructing a highly stable one-dimensional (1D) nanorod-intercalated GO composite membrane. The surface carboxyl density of GO was enhanced through modification, and Fe 3 O 4 nanoparticles were grown on the surface of 1D attapulgite (FATP) to adjust the hydroxyl density and roughness. The results indicate that strong interactions are formed between FATP and carboxylated graphene oxide (CGO), enhancing the binding force to −1.38 × 10 4 kcal·mol −1. Benefiting from the intercalation effect and hydrophilic characteristics of FATP, the composite membrane exhibits a relatively high pure water flux (1630.5 L·m −2 ·h −1 ), hydrophilicity (water contact angle of 63°), and underwater superoleophobicity (underwater oil contact angle of 159°). In the O/W separation process, the composite membrane can effectively repel oil droplets with stable flux and oil rejection of 175.6 L·m −2 ·h −1 and > 98 %, respectively. Furthermore, the membrane exhibits excellent stability with steady permeability remaining approximately 80.2 % of the original value after multiple cycles of operation in diverse acidic and alkaline environments.