Cellulose and its composite for sustainable oils/water (O/W) separation: From cellulose sponge to 3D printed nanocellulose

Discharge of oil-containing wastewater can pollute the aquatic environment, because oil can inhibit the supply of oxygen from the atmosphere to surface water and reduce the penetration of sunlight into the water. Oxygen and sunlight are important factors in aquatic ecosystems. Oil is especially difficult to be separated from water when the two compounds have formed an emulsion system. Membrane-based separation technology was developed to remove various pollutants in wastewater, including oil and microorganisms. Nanocellulose-based oil/water (o/w) separators are considered as green technologies that are efficient in separating oil pollutant and other impurities from water. The superior performance of the technology is attributed to the high surface area, crystal structure, and many hydroxyl groups (-OH). The excellent chemical and physical structure of the membrane allows for the ideal and effective separation of the emulsions/mixtures. In addition, the great and compact cellulose hydrogen bonds affect the membrane's strong network structure. In this work, we present and review the research trend of o/w separator membranes based on nanocellulose composites, including their development with 3D printing technology. Antimicrobial properties and their opportunities in printing oil-degrading microbes for oil biodegradation processes are also discussed. The multifunctional o/w separator membrane based on nanocellulose composites is expected to contribute to the development of green technologies, especially related to the preparation and synthesis methods, addition of antimicrobial agents, biodegradability properties, 3D printing complexity and functionality, as well as the long-term sustainability.