A sandwich-like structured superhydrophobic fabric for versatile and highly efficient emulsion separation

A Solar-Heated Phase Change Composite Fiber with a Core-Shell Structure for the Recovery of Highly Viscous Crude Oil

Due to the high viscosity and low fluidity of viscous crude oil, how to effectively recover spilled crude oil is still a major global challenge. Although solar thermal absorbers have made significant progress in accelerating oil recovery, its practical application is largely restricted by the variability of solar radiation intensity, which is influenced by external environmental factors. To address this issue, this study created a new composite fiber that not only possesses solar energy conversion and storage capabilities but also facilitates crude oil removal. PF@PAN@PEG was obtained by coaxial electrospinning processing, with PEG within PAN fibers, and a coating layer was applied to the fiber surface to impart oleophilicity and hydrophobicity. PF@PAN@PEG exhibited a high latent heat value (77.12 J/g), high porosity, and excellent photothermal conversion and oil storage capabilities, significantly reducing the viscosity of crude oil. PF@PAN@PEG can adsorb approximately 11.65 g/g of crude oil under sunlight irradiation. Notably, due to the encapsulation of PEG, PF@PAN@PEG can continuously maintain the crude oil at a phase change temperature by releasing latent heat under specific conditions, effectively reducing its viscosity with no PEG leakage at all. When solar light intensity varied, the crude oil collection efficiency increased by 21.99% compared to when no phase change material was added. This research offers a potential approach for the effective use of clean energy and the collection of viscous crude oil spill pollution.

Joule Heating-Assisted Crude Oil Purification by a Poly(pyrrole)-Modified Microfibril Cellulose Membrane

Using membrane materials to purify viscous watery oil from industrial production processes and accidental oil spills is of great importance but still challenging. Based on the excellent electrical conductivity and electric-thermal conversion of poly(pyrrole) (PPy), a hydrophobic PPy-modified micro-fibrillated cellulose membrane (P-CP) was successfully prepared. The size of the P-CP membrane can be customized to meet specific requirements. In this research, the membrane diameter is capable of reaching 24 cm. By applying a voltage ranging from 0 to 12 V, the surface temperature of the P-CP membrane can be elevated to roughly 120 °C. After 10 cycles of heating and cooling under 12 V voltage, the electric-thermal curves, surface hydrophobicity, and pore structure of P-CP membrane can remain stable, which suggests remarkable electric-thermal stability and reliability despite prolonged operation. The P-CP membrane shows good linearity between voltage and current (R2 = 0.997) and easy temperature control from room temperature to ∼120 °C at low supply voltage (0-12 V). Under the condition of 12 V power supply and self-gravity, the separation flux of the P-CP membrane for water-in-oil (W/O) emulsions (kerosene, diesel) is 2-3 times higher than that at room temperature, and the separation efficiency is also improved. Importantly, the P-CP membrane shows excellent separation performance for high viscosity water-in-crude oil emulsions, with a separation flux of 40 L m-2 h-1 by gravity. Compared to the situation without electricity, the separation flux of water-in-crude oil emulsion has increased four-fold. The joule heating of the P-CP membrane expands its service time and application scenarios, demonstrating its great application prospects in actual viscous oil-water emulsion separation.

Study on Electrochemical Performance of MnO@rGO/Carbon Fabric-Based Wearable Supercapacitors

In this work, we reported the electrochemical performance of a type of carbon fabric-based supercapacitor by coating MnOx@rGO nanohybrids on carbon fabric with a simple one-step hydrothermal method. We studied the mass ratio of MnOx to rGO on the electrochemical properties of the carbon fabric-based supercapacitors. We found that as the mass ratio is 0.8:1 for MnO@rGO, the supercapacitor with a loading of 5.40 mg cm^-2 of MnO@rGO nanohybrids on carbon fabric exhibits a specific capacitance of 831.25 mF cm^-2 at 0.1 mA cm^-2 current density. It also shows long-term cycling capacitance retention of 97.2% after 10,000 charge-discharge cycles at a current density of 0.4 mA cm^-2. We speculate that the high electrochemical performance results from the strong interfacial bonding between the hierarchical architecture of MnO@rGO nanohybrids and carbon fabric.

Superhydrophobic polyurethane sponge for efficient water-oil emulsion separation and rapid solar-assisted highly viscous crude oil adsorption and recovery

Rapid and efficient cleaning of oily wastewater and high viscosity crude oil spills is still a global challenge. Conventional three-dimensional porous adsorbents are ineffective for oil-water separation in harsh environment and are restricted to the low fluidity of high viscosity crude oil at room temperature. Increasing temperature can enormously improve the fluidity of viscous crude oil. Herein, the polydimethylsiloxane (PDMS) /carbon black (CB) -modified polyurethane sponge (PU) were prepared by a simple one-step dip-coating method. PDMS/CB@PU (PCPU) exhibits high adsorption capacity to various oils and organic liquid (28.5-68.7 g/g), strong mechanical properties (500 cycles at 50%), outstanding reusability (100 cycles of adsorption and desorption) and excellent environmental stability due to the special PDMS/CB coating. The maximum surface temperature of PCPU sponge can reach 84.7 ℃ under 1 sunlight irradiation. Therefore, the PCPU sponge can rapidly heat and enhance the fluidity of viscous crude oil, significantly speeding up the viscous oil recovery process with the maximum adsorption capacity of 44.7 g/g. In addition, the PCPU sponge can also combine with the vacuum pump to realize the continuous and rapid repair of viscous oil spills from the seawater surface. In consideration of its simple preparation, cost-effectiveness and high oil absorption ability, this solar-assisted self-heating adsorbent provides a new direction for large-scale cleanup and recycling of viscous crude oil spill on the seawater surface.

Rosin acid and SiO2 modified cotton fabric to prepare fluorine-free durable superhydrophobic coating for oil-water separation

Currently, fluorides and long-chain aliphatic compounds are the most frequent low surface energy chemicals utilized in the preparation of superhydrophobic coatings, but associated environmental risks and instability restrict their potential application in oil-water separation. This research described a superhydrophobic coating based on rosin acid and SiO₂ modified cotton fabric to overcome this challenge. By means of spray impregnation and UV-assisted click reaction, sulfhydryl modified rosin acid (RA), Octavinyl-POSS, and SiO₂ were grafted onto the surface of cotton fabric to obtain RA-SiO₂ superhydrophobic coating with rough surfaces such as lotus leaf and low surface energy. The RA-SiO₂ superhydrophobic coating had favorable self-cleaning ability, and also adsorbed various light and heavy oils to achieve efficient separation of oil-water mixtures. The separation efficiency was 96.3% and the permeate flux was 6110.84 (L⋅m^-2⋅h^-1) after 10 repetitions. The RA-SiO₂ superhydrophobic coating was found to be effective in separating oil-in-water and oil-in-water emulsions, and the separation mechanism was elaborated. In addition, it could effectively separate emulsions even after mechanical abrasion and chemical immersion, and had excellent stability. The fluorine-free and environmentally friendly low-cost superhydrophobic coating based on rosin acid is expected to play a significant potential in oil-water separation applications due to its excellent separation performance.

Wodyetia bifurcate structured carbon fabrics with durable superhydrophobicity for high-efficiency oil-water separation

The superhydrophobic fiber-based membranes with features of high separation efficiency and low energy consumption for oil-water separation remains a formidable challenge. In this paper, a robust and durable superhydrophobic cotton-derived carbon fabric (CDCF) with wodyetia bifurcate-like structure is fabricated via in situ cobalt-nickel basic carbonate (CNC) deposition and 1 H, 1 H, 2 H, 2 H-perfluorooctyltriethoxysilane (POTS) coating. The combined action of rough surface structure and low surface energy makes CDCF/CNC/POTS with superhydrophobicity/superoleophilicity, anti-wetting, and self-cleaning performance. Intriguingly, the CDCF/CNC/POTS can keep its superhydrophobicity under of the water droplet impact pressure of 781 Pa. In addition to its robust dynamic superhydrophobicity, CDCF/CNC/POTS can also maintain its non-wetting property under harsh environmental conditions such as mechanical abrasion treatment, acidic, alkaline and salt solutions, and ultraviolet radiation. Importantly, the CDCF/CNC/POTS can separate various oil-water mixtures and emulsions under gravity with ultrahigh oil-water mixtures permeate flux (∼19,126 L/m²h), high surfactant-stabilized emulsion permeate flux (∼821 L/m²h), and high separation efficiency (> 98.60 %). Moreover, remarkable recyclability endow the CDCF/CNC/POTS with promising application in treating oily wastewater. This work may benefit the low-cost mass production of cotton-based carbon fabrics for developing eco-friendly high-efficiency separators.