Superhydrophobic aerogel membrane with integrated functions of biopolymers for efficient oil/water separation

Abstract

A novel type of superhydrophobic biopolymer aerogel membrane (T-SA/lignin x /rGO-MTMS) is prepared for purifying oily wastewater. • A novel type of superhydrophobic biopolymer aerogel membrane between lignin and sodium alginate (T-SA/lignin x /rGO-MTMS) was prepared. • Confirmation of cooperative interaction between lignin and sodium alginate. • Demonstration of high-efficiency cyclicity for oil/water separation. • Degradable oil/water separation membranes. Superhydrophobic membranes have been playing crucial role in efficient remediation of organic pollutants contaminated water, especially for oily discharged wastewater. Taking advantages of the inherent features of graphene oxide (GO), sodium alginate (SA) and lignin, a novel type of superhydrophobic biopolymer aerogel membrane (T-SA/lignin x /rGO-MTMS) was prepared by freeze-casting technique and subsequent chemical vapor deposition, during which trimethoxymethylsilane (MTMS) silylation growth was achieved for the supreme protuberance, leading to the formation of rough and hydrophobic surface that favorably looks like a hedgehog carrying apples. Due to the air cushion induced by cooperative interaction between rough lignin particles and SA of 3D porous network with gas as a dispersion medium, and crumpled GO nanosheets, as-fabricated membrane with integrated functions of biopolymers possessed superhydrophobic surface characteristics (WCA = 161°). More favorably, utilizing the inherent molecular features, lignin has been successfully employed to de-oxidize GO during this preparative concept. By virtue of the low-surface-energy reduced GO (rGO) and abundant protuberance, T-SA/lignin x /rGO-MTMS exhibited potential cycling performance even with 10 cycles of oil/water separation and oil sorption. This study might shed light on the value-added utilization of integrated functions of biopolymers for designing task-specific functional materials for various applications.