Surfactant-free emulsion of epoxy resin/sodium alginate for achieving robust underwater superoleophobic coating via a combination of phase separation and biomineralization.

Underwater superoleophobic coatings exhibit promising prospects in the field of oil contamination resistance. However, their poor durability, stemming from the fragile structures and unstable hydrophilicity, greatly restricted their development. In this report, we proposed a novel strategy of combination water-induced phase separation and biomineralization to prepare the robust underwater superoleophobic epoxy resin-calcium alginate (EP-CA) coating by utilizing a surfactant-free emulsion of epoxy resin/sodium alginate (EP/SA). The EP-CA coating not only exhibited excellent adhesion to various substrates, but also had remarkable resistance to the physical/chemical attacks such as abrasion, acid, alkali and salt. It could also protect the substrate (e.g., PET substrate) from the damage of organic solution and the fouling of crude oil. This report provides a new perspective to fabricate robust superhydrophilic coating with a facile way.

Novel Environmentally Friendly Waterborne Epoxy Coating with Long-Term Antiscaling and Anticorrosion Properties.

Metal pipes in industrial production are exposed to various corrosive ions. The combined action of these ions with oxygen in water causes corrosion and contamination of the metal pipes and equipment. In addition, metallic ions in water react with anions to form scale on the surface of the metal, which significantly reduces the service life of the metal and equipment, resulting in safety hazards. Waterborne coatings have attracted tremendous attention due to the less negative impact on the environment, but their practical applications are severely restricted by poor barrier properties and poor mechanical durability. Herein, the barrier properties of water-based coatings are successfully improved by adding functional slow-release nanofillers, and the fillers also endow the coating with excellent antiscaling properties. A functional slow-release nanofiller (lecithin/SiO2/HEDP) was prepared using HEDP (etidronic acid) as the scale inhibitor active material and SiO2 as the carrier, combined with a phospholipid membrane with slow-release permeability. With the addition of slow-release fillers, compared with the EP coating, the impedance modulus of composite coatings increases about 1 order of magnitude, the scale inhibition rate is as high as 80.7%, and the antiscaling life is double that of the coating without the phospholipid-coated filler. Thus, this study is expected to provide a new perspective for the preparation of new slow-release fillers and high-efficiency scale inhibitor coatings.

A sustainable dynamic redox reaction passive film for long-term anti-corrosion of carbon steel surface.

CeO2 was used as the only oxidant for aniline polymerization, and polyaniline (PANI) was grown on CeO2 surface to form CeO2@PANI nanocomposites. SEM and TEM showed that the CeO2@PANI composites were nanorods in a core-shell structure. XPS indicated that CeO2-core was reduced by aniline into Ce3+, which was then captured by the PANI-shell. Then the passive ability of CeO2@PANI coating on steels was explored. EIS showed that the impedance modulus of the CeO2@PANI coating exceeded 108 Ω·cm2 after accelerated immersion. The SVET and XPS confirmed that PANI polarized the anodic reaction, Ce3+ suppressed the cathodic reaction, and PO43- formed complex precipitation. Some high-valent metal oxides can directly oxidize the aniline polymerization to form MO@PANI hybrid particles. The cations obtained by the metal oxide reduction can be captured by PANI and participate in passivation together with dopants. This study provides a new kind of nanocomposite fillers that can effectively passivate steel substrates within epoxy coatings for long-time protection.

Hierarchical MnO2 nanoflowers blooming on 3D nickel foam: A novel micro-macro catalyst for peroxymonosulfate activation.

In this work, birnessite-type δ-MnO2 nanoflowers were uniformly deposited on 3D nickel foam (NF) by one-step hydrothermal route for high-efficient activation of peroxymonosulfate (PMS) towards degradation of acid orange 7 (AO7). High specific surface area, large pore volume and 3D hierarchical structure promotes the mass and electron transfer for great catalytic activity. Low reaction energy barrier (Ea = 27.5 kJ/mol) and outstanding reusability with extremely low manganese leaching during recycling (<0.06 mg/L) was achieved due to the 3D hierarchical structure which could effectively avoid the agglomeration of nano-sized MnO2. SO4- was confirmed to be the predominant reactive species for AO7 decomposition by electron spin resonance and quenching tests. The synergistic catalytic mechanism of MnO2/NF and the role of inner-sphere complexation between the active sites of MnO2 and peroxymonosulfate were thoroughly investigated. Compared with traditional nano/micro-sized catalysts, 3D macroscopic MnO2/NF with facile recovery and high stability potentially facilitates fascinating applications as green heterogeneous catalysis approach.

Ultrahigh-flux (>190,000 L·m-2h-1) separation of oil and water by a robust and durable Cu(OH)2 nanoneedles mesh with inverse wettability.

Single-stage oil/water separation membranes usually suffer from weak chemical stability, susceptible mechanical damage and relatively low permeating flux, and the sophisticated preparation processes also limit their massive utilization. In this work, Cu(OH)2 nanoneedles coated copper mesh (CM) is prepared by simple and eco-friendly anodic oxidation at a current density of 4 mA/cm2 for 6 min, which is the most efficient route reported so far. The mesh exhibits outstanding superhydrophilicity and underwater superoleophobicity towards various oils with contact angles up to 164.9°, achieving superior oil/water separation efficiency of above 99.5% and ultrahigh permeating flux of 191 160 L·m-2h-1 solely driven by gravity. Impressively, the Cu(OH)2/CM demonstrates excellent chemical stability and anti-fouling performance when exposed to acidic and strongly alkaline solutions, saturated NaCl solution and various organic solvents. High durability to withstand mechanical challenges, e.g. high-power sonication and sand abrasion, is experimentally confirmed owing to strong cohesional strength of Cu(OH)2 nanoneedles on CM surface. Importantly, the Cu(OH)2/CM exhibits favorable long-term recyclability with stable microstructure morphologies even after 50 cycles. These distinct advantages endow the Cu(OH)2/CM to be an ideal candidate to efficiently separate oil pollutants from water. The oil/water separation mechanisms are proposed based on the concept of intrusion pressure.