Comparison of Anti-Icing, Antifouling, and Anticorrosion Performances of the Superhydrophobic and Lubricant-Infused Coatings Based on a Hollow-Structured Kapok Fiber.

The superhydrophobic surface and slippery liquid-infused porous surface (SLIPS)/lubricant-infused surface (LIS) have attracted increasing attention owing to their multifunctionality. However, their practical applications face several problems such as complex and inefficient preparation technology, loss of lubricant, and fragile microstructures. Therefore, new strategies for preparing microstructures must be developed for constructing superhydrophobic and lubricant-infused coatings. Herein, a low-cost and high-efficiency method for developing superhydrophobic and lubricant-infused coatings based on in situ grown TiO2 on the surface of a hollow kapok fiber (KF) is reported. The anti-icing, antifouling, and anticorrosion performance of the superhydrophobic and lubricant-infused coatings are compared. The superhydrophobic coating reduces the formation and accumulation of ice. The lubricant-infused coating exhibits an extremely low ice adhesion strength and durable anti-icing properties. The superhydrophobic and lubricant-infused coatings show the outstanding antifouling property of diatom; the superhydrophobic surface exhibits superior stability over LIS without an external force field. The lubricant-infused coating shows excellent corrosion resistance and durability when immersed in a 3.5% NaCl solution. The superhydrophobic coating loses its protection as a result of the corrosion media permeating the metal substrate via the electrolytic cell and coating interface, and the lubricant-infused coating provides lasting corrosion resistance because of the lubricant filling into the interface. Although the superhydrophobic coating is fragile and the lubricant-infused coating will lose lubricant, this simple and convenient approach can be repeated to keep the coatings active. This study provides new inspiration for the fabrication of superhydrophobic surfaces and LIS based on natural products.

Fabrication of MnCuNiFe-CuAlNiFeMn Gradient Alloy by Laser Engineering Net Shaping System.

Marine noise pollution generated by propellers is of wide concern. Traditional propeller materials (nickel-aluminum bronze (NAB) alloys) can no longer meet the requirements for reducing shaft vibration. However, the Mn-Cu alloy developed to solve the problem of propeller vibration is affected by seawater corrosion, which greatly limits the application of the alloy in the field of marine materials. In this study, the M2052-NAB gradient alloy was developed for the first time using LENS technology to improve the corrosion resistance while retaining the damping properties of the M2052 alloy. We hope this alloy can provide a material research basis for the development of low-noise propellers. This study shows that, after solution-aging of M2052 alloy as the matrix, the martensitic transformation temperature increased to approach the antiferromagnetic transformation temperature, which promoted twinning and martensitic transformation. The aging process also eliminated dendrite segregation, promoted the equiaxed γ-MnCu phase, and increased the crystal size to reduce the number of dislocations, resulting in obvious modulus softening of the alloy. NAB after deposition had higher hardness and good corrosion resistance than the as-cast alloy, which offers good corrosion protection for the M2052 alloy. This research provides new material options for the field of shipbuilding.

Co-construction of molecular-level uranyl-specific "nano-holes" with amidoxime and amino groups on natural bamboo strips for specifically capturing uranium from seawater.

Efficiently capturing of uranium (VI) [U(VI)] from seawater elicits unparalleled attraction for sustaining the uplifted requirement for nuclear fuel. However, obtaining the abundant U(VI) resource from seawater has always seriously restricted by competitive adsorption from higher concentrations of competitors, especially vanadium (V) [V(V)]. Herein, based on amidoximized natural bamboo strips with hierarchical porous structure, the molecular-level uranyl-specific "nano-holes" was co-constructed by the intramolecular hydrogen bonds for specifically trapping U(VI) from seawater. Manipulating the branched degrees of amino groups enabled the creation of a series of the molecular-level uranyl-specific "nano-holes" that exhibit ultrahigh affinity and selective adsorption of U(VI) with a adsorption capacity 1.8 fold higher compared to that of V(V) after 30 days floating in the Yellow Sea basin, conquering the long-term challenge of the competitive adsorption of V(V) for amidoxime-based adsorbents applied to extract U(VI) from seawater. The diameter of the molecular-level uranyl-specific "nano-holes" is approximately 12.07 Å, significantly larger than (UO2)3(OH)3+ (10.37 Å) and smaller than HV10O285-, thereby exhibiting specifically trapping of U(VI) in a series of adsorption experiments with different U(VI)-V(V) ratios. Besides, the adsorption model based on the combination of experimental and theoretical results is accompanied by "hydrogen bond breaking and coordination bond formation".

Ultra-high flexibility amidoximated ethylene acrylic acid copolymer film synthesized by the mixed melting method for uranium adsorption from simulated seawater.

If U(VI) in seawater (unconventional uranium resource) can be extracted efficiently, it can provide important supplies and guarantees for the stable development of nuclear power. In this study, a mixing melting method without condensation agent was proposed to prepare ultra-high flexibility and different proportions DAMN modified EAA resin film (EAA-DAMN) through the condensation reaction between -COOH and -NH2 and the uniform mixing of liquid EAA and DAMN. In addition, the dense film structure and -CN of EAA-DAMN were transformed into multiple pores structure and amidoxime groups of the amidoximated EAA (AO-EAA) by amidoxime reaction. The AO-EAA-3 showed the most excellent adsorption performance (qe=146.40 mg g-1) at pH = 5, which was 2.33 times that of EAA. Moreover, a hypothesis was proposed for the first time that -NH2 in the material could combine with H+ ionized by water to form -NH3+, and then adsorbed NO3- in the solution through electrostatic attraction, and O element from NO3- adsorbed on the surface and N-O from amidoxime groups of material as the adsorption active sites performed coordination with U(VI), thereby improving the adsorption performance of AO-EAA.

Ultra-high mechanical property and multi-layer porous structure of amidoximation ethylene-acrylic acid copolymer balls for efficient and selective uranium adsorption from radioactive wastewater.

Adsorption uranium [U(VI)] from U-containing radioactive wastewater (URW) is a critical strategy for solving the resource shortage and environmental pollution in pace with the sustainable development of nuclear energy. However, the URW universally exhibits acidity and contains co-existing metal ions with high concentration. Herein, the amidoximation ethylene-acrylic acid copolymer balls (EAA-AO) with aciduric and super-high mechanical property were successfully synthesized through grafting diaminomaleonitrile and further treatment of amidoximation. Significantly, the mechanical properties of EAA-AO were not affected by the grafting process and maintained super-high mechanical properties. Furthermore, the -NH2 and unreacted -CN groups in diaminomaleonitrile adjusted the pKa to make the optimal pH be 4. In addition, the microstructure of EAA-AO was transformed from the original dense to multi-layer porous structure, which promoted the mass transfer process and the contact between uranyl ions (UO22+) and internal adsorption active sites. The adsorption capacity of EAA-AO was about 1.78 times that of EAA at pH = 4, and the adsorption capacity for U(VI) was about 8.17 times that of Ba2+ with the second highest adsorption capacity. Therefore, the EAA-AO exhibited ultra-high adsorption performance (qe = 3.196 mg g-1) in the artificial radioactive wastewater, laying a good foundation for subsequent large-scale industrial adsorption of U(VI) in nuclear industrial wastewater.

Anti-bacterial and super-hydrophilic bamboo charcoal with amidoxime modified for efficient and selective uranium extraction from seawater.

With the growing demand for nuclear energy, uranium extraction from seawater (UES) is becoming increasingly important due to the ocean reserves 4.5 billion tons for uranium(VI) [U(VI)]. Herein, two kinds of amidoxime modified bamboo charcoal (AOOBCS and AOOBCH) with porous structure, anti-bacterial, and super-hydrophilic properties were successfully synthetized by two etching methods (soaking and hydrothermal). The super-hydrophilic property of AOOBCH accelerated the contact between the amidoxime group and uranyl ions (UO22+), and promoted the action of anti-bacterial substances (bamboo-quinone) on bacteria to restrain the form of bacterial membrane. In addition, the amidoxime groups not only didn't destroy the super-hydrophilic surface, but also adjusted the adsorbents' pKa by changing the amidoxime grafting rate. Under PH = 7, the adsorption capacity of AOOBCH was about 1.97 times that of AOOBCS and 2.95 times that of BC. Importantly, the AOOBCH exhibited ultra-high uptake capacity (6.37 mg g-1) and exceptional selectivity for U(VI) in 100-fold interfering ions simulated seawater system due to the chelation between C(NH2)NOH and UO22+ to form a more stable coordination structure (Eads = -36.56 eV). Benefiting from the superior performance and selectivity, the AOOBCH is a potential candidate for UES.