Nacre-like graphene oxide-calcium carbonate coated membrane with underwater superoleophobic property for highly efficient oil/water separation

Recently, oily wastewater is causing serious environmental pollution, and an effective disposal method is highly urgent. Membranes with superhydrophilic and underwater-superoleophobic (SUS) properties have shown prospective advantages. The development of a new nacre-like Li-Bentonite/graphene oxide-calcium carbonate coating membranes (Li-Bent/GO-CaCO3@PVDF CMs) was motivated by the unique mastoid structure of the lotus leaf and the robust layer of the nacre. This CMs were synthesized using a facile, cost-effective, and eco-friendly layer-by-layer (LBL) self-assembly approach. The commercially available polyvinylidene fluoride (PVDF) was utilized as a stable base for the fabrication of the CMs. Among these, GO nanosheets were introduced to imitate the "brick and mortar" structure of mother-of-pearl, and "hard bricks" with interspersed Li-Bent and GO were obtained by the LBL self-assembly method. The phenomenon of "biomineralization" confers an intricate surface structure to the membrane, thereby imparting it with a hydrophilic property of 8.3 degrees and an exceptional nonadhesive behavior in submerged conditions. In addition, the membrane has SUS performance and superior permeability (WF - 5476.3 & PLUSMN; 76 L & BULL;m- 2 & BULL;h-1), separation (OF-3123.78 & PLUSMN; 56 L & BULL;m- 2 & BULL;h- 1, OR - 99.3 %) and antifouling properties (FRR decreased only 14.9 %). Significantly, the membrane has good stability, such as alkali, salt-resistance and aging-resistance. Moreover, this method is easy to operate, and is suitable for surface modification of diversified substrate membranes, with high research and application value.