New Progress in Biomimetic Magnetic Demulsifiers
The discharge of industrial oily wastewater and the pollution of oily wastewater caused by oil spills at sea have seriously threatened human health and the ecological environment. Superhydrophobic oil-absorbing materials have received extensive attention in the selective separation of oil/organic solvents from water due to their high porosity, excellent adsorption capacity, and reusability. In the separation of highly emulsified oil-in-water emulsions, the solid (superhydrophobic adsorption material surface)/gas (air cushion)/liquid (water)/liquid (oil droplets) multiphase formed by the air cushion captured on the surface of the superhydrophobic adsorption material The structure severely hinders the interaction between superhydrophobic adsorbents and oil-in-water droplets, resulting in the inability of these materials to effectively separate oil contaminants from oil-in-water emulsions. How to enhance the interfacial interaction under multiphase systems through the design and fine-tuning of material structure and surface chemical properties to achieve efficient separation of oil-water emulsions is still a challenging problem.
Recently, Xu Yong, researcher Zeng Zhixiang, and associate researcher Wang Gang of the marine environmental materials team of Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, based on their research foundations in the preparation of superwettable materials and their oil-water separation (Green Chem., 2015, 17: 3093-3099; ACS Appl. Mater. Inter., 2015, 7: 26184?26194; Appl. Surf. Sci., 2018, 458: 167-175; J. Membr. Sci., 2019, 573,126-134; ACS Appl Mater. Inter., 2020, 12, 51102-51113; ACS Appl. Mater. Inter., 2020, 12, 55894-55902; Sep. Purif. Technol., 2021, 262: 118310-118320; J. Hazard. Mater ., 2021, 407: 124374-124392, etc.), inspired by the backside water collection and directional water transport capabilities of desert beetles, through the surface microstructure construction and surface molecular modification of two-dimensional materials, we designed and developed a superhydrophobic Magnetic demulsification particles for /hydrophilic combination and photothermal assisted cyclic regeneration.
In this work, a biomimetic microstructure of the back of a desert beetle was constructed on the surface of graphene oxide (GO) by one-step solvothermal method and mechanical ball milling method. The superhydrophobic/hydrophilic microstructure based on Fe3O4 grain bridging endows the magnetic composite particles (Fe3O4/GO@C-SR) with high hydrophobicity/lipophilicity in air and high oleophobicity in water . Under the synergistic effect of directional oil adsorption and local barrier effect of the superhydrophobic/hydrophilic composite structure, Fe3O4/GO@C-SR particles can achieve rapid demulsification of oil-in-water emulsions, continuous capture and coalescence of tiny oil droplets. In addition, the introduction of Fe3O4 grains and carbon black particles can improve the light absorption rate of GO microflakes in broadband wavelengths, effectively enhancing the photothermal performance of Fe3O4/GO@C-SR particles. The excellent oil-water separation performance and green and energy-saving recycling and regeneration performance make Fe3O4/GO@C-SR particles expected to be widely used in the field of oily wastewater treatment (Figure 2).
The work was published in the international journal Chemical Engineering Journal under the title “Desert beetle-like microstructures bridged by magnetic Fe3O4 grains for enhancing oil-in-water emulsion separation performance and solar-assisted recyclability of graphene oxide” (https://doi. org/10.1016/j.cej.2021.130904). This research was supported by the National Natural Science Foundation of China Youth Fund Project (51703235), the National Natural Science Foundation of China Joint Fund Project (U1809214 and U1809213), and the Open Project of the Key Laboratory of Marine New Materials and Applied Technology of the Chinese Academy of Sciences (2019K04).
Figure (a) Schematic diagram of the preparation of Fe3O4/GO@C-SR particles inspired by the back of desert beetles; (b) schematic diagram of hydrophilic/superhydrophobic microstructures with water collection and water retention on the back of Stenocara beetles; (c) Fe3O4/ Micromorphology of GO@C-SR particles; (d) Effect of addition amount on the separation performance of Fe3O4/GO@C-SR particle emulsion; (e) Separation mechanism of Fe3O4/GO@C-SR particle on crude oil-in-water emulsion