Copyright © 2022 Foshan MBRT Nanofiberlabs Technology Co., Ltd All rights reserved.Site Map
Crude oil is an indispensable resource for the sustainable development of human society. However, with the rapid development of the global economy, watery oils and accidental oil spills generated during industrial production have caused serious economic losses. In the past half century, many techniques have been developed to separate various oil-water mixtures, such as skimming, emulsion breaking and adsorption. However, effective treatment of oil-water emulsions is still a great challenge due to the high stability and tiny size (diameter <20 μm) of the droplets. Conventional emulsion separation techniques include physical (gravity, centrifugation, membrane separation, etc.), chemical (flocculation, deep oxidation, combustion, etc.), and biological (aerobic, anaerobic biodegradation, etc.) methods. These technologies have shown some ability in separating emulsions, but they also have typical drawbacks such as high cost, large installation space, susceptibility to secondary contamination, and time-consuming. In recent years, membrane separation technology has shown great potential in emulsion separation due to its advantages of easy operation, high separation efficiency and no secondary pollution. Porous materials with selective super-wettability are considered to be one of the most cutting-edge candidates in the field of oil-water separation.
However, it should be noted that the viscosity of oil tends to affect the separation flux and separation efficiency of emulsions. Most of the membrane materials that have been reported are only suitable for light oils or organic solvents. When they are used to treat high viscosity emulsions, especially crude oil emulsions, the low separation flux results in ineffective membrane separation processes. Therefore, the design and preparation of membrane materials for the treatment of emulsions formed from high-viscosity oil phases remains a great challenge.
The main point of this paper
Importance of cellulose:
Cellulose is the world's most abundant naturally occurring polysaccharide polymer compound that is sustainable, biodegradable and biocompatible.
Properties of Cellulose:
It has superior mechanical properties, good thermal stability and high aspect ratio.
Application areas of cellulose:
Energy, soft actuators, construction, biomedical engineering, photovoltaics and many other fields.
Application of cellulose-based materials in oil-water separation:
Cellulose-based membranes or aerogels are designed for oil-water separation with high separation performance (> ~ 99%).
Examples of specific applications of cellulose-based materials:
Superhydrophilic and immersed superoleophobic hydrogel-coated filters prepared by Jiang et al. using cellulose filter paper and polyvinyl alcohol (PVA).
Aerogel sponges prepared from carboxycellulose nanofibers (CNFs) and thermoplastic polyurethane elastomers with oil-bottom superhydrophilicity, water-absorbency, compressibility and recyclability.
Anisotropic balsa wood sponges with high mechanical compressibility and elastic recovery with oil absorption up to 41 g g-1.
Challenges:
Controlling the selectivity of membrane materials, simplifying the preparation process, and achieving large-scale production are the challenges faced by cellulose-based membrane materials in the field of oil-water separation.
Demand for sustainable development:
The desire for renewable resources in the context of the global energy crisis has driven the research and application of cellulose-based materials.
Joule heat-driven polypyrrole-modified microfibrillated cellulose membranes: efficient oil-water separation technology
Polypyrrole (PPy) applications:
Hydrophobic PPy-modified microfibrillated cellulose membranes (P-CP) were prepared using the electrical conductivity and electrothermal conversion of PPy.
Characterization of P-CP membranes:
The size can be customized, up to 24 cm in diameter in this study.
The surface temperature can be increased to about 120°C by applying a voltage from 0 to 12 V. The surface temperature can be increased to about 120°C by applying a voltage from 0 to 12 V.Electro-thermal stability and reliability are high, and performance remains stable after multiple heating and cooling.
Electrothermal performance:
Good linear relationship between voltage and current (R2 = 0.997).
Easy to control temperature range from room temperature to approx. 120°C at low supply voltage of 0-12 V.
Oil-water separation performance:
Under 12 V power supply and self gravity conditions, P-CP membranes provide 2-3 times higher separation flux for water-in-oil (W/O) emulsions than at room temperature.
Good separation performance for high viscosity crude oil-in-water (W/O) emulsion with gravity separation flux of 40 L m-2 h-1.
Advantages of Joule heating:
Separation flux of water-in-oil emulsions is increased by a factor of 4 compared to the electroless case.
Joule heating extends the usage time and application scenarios of P-CP membranes, which is promising for practical applications.
Challenges and solutions:
Despite the potential of membrane materials in oil-water separation, controlling selectivity, simplifying the preparation process, and scaling up production remain challenges.
Joule heating of P-CP membranes provides a possible solution to improve the separation efficiency and flux through electrothermal assistance.
In summary, Joule-heated P-CP membranes were prepared using environmentally friendly cellulose and polypyridine. The rational microstructural design of the P-CP membranes resulted in excellent hydrophobicity, excellent electrical conductivity, and good electro-thermal conversion properties.The thickness of the P-CP membranes was about 800 μm, with an average pore size of 9.81 μm and a tensile strength of 69 kPa.The P-CP membranes can be fabricated in different sizes according to the needs. In this study, the diameter of the membrane was up to 24 cm. the voltage and current inside the P-CP membrane were highly linear (R2 = 0.997). The surface temperature of the P-CP membrane can be increased from room temperature to ~ 120°C by applying a voltage of 0 ~ 12 V. The electro-thermal profile, surface hydrophobicity, and pore structure of the P-CP membrane remained stable after heating and cooling for 10 times at a voltage of 12 V, indicating that the P-CP membrane still possesses good electro-thermal stability and reliability under prolonged operation.The P-CP membrane possesses a remarkable electro-thermal conversion performance P-CP membrane has remarkable electro-thermal conversion performance, and the separation flux of emulsions with different viscosities, especially thick oil-in-water emulsions, has been improved by nearly 2-3 times. With electro-thermal assistance, the P-CP membrane can increase the separation flux of crude oil emulsions by nearly 4 times only by self-gravity. With simple, scalable fabrication methods and environmentally friendly, renewable raw materials, multifunctional cellulose-based P-CP membranes have great potential for next-generation thermal management membrane materials and oil-water treatment applications.
