Single–sided superhydrophobic fluorinated silica/poly(ether sulfone) membrane for SO2 absorption

Efficient direction-independent 3D spiral fog collector

Inspired by the natural structures of cacti and desert beetles, a novel three-dimensional (3D) high-efficiency fog collector is proposed. This design integrates a unique macro-structural configuration with a surface wettability gradient that remains independent of the fog flow direction. The fog collector adopts an integral spiral structure, with superhydrophilic triangular protrusions uniformly distributed across its surface. Under optimized design conditions, with a folding angle of 60 degrees, the collector features 23 superhydrophilic protrusions, each measuring 2.5 × 5 mm. Under these conditions, the fog collection efficiency reaches 0.5057 g cm-2 min-1. Furthermore, to assess the practical feasibility of the fog collector, a series of experiments, including sand impact and chemical resistance tests, were conducted. The experimental results show that the contact angle of the fog collector's surface remains high, indicating its excellent stability and durability. The fog collector not only uses a low-cost aluminum plate as the base material but also incorporates a simple and efficient preparation process, significantly enhancing its design feasibility and practicality. The results presented in this study offer a novel approach to designing high-efficiency fog collectors that are unaffected by the direction of fog flow.

CO2/CH4 separation performance of SiO2/PES composite membrane prepared by gas phase hydrolysis and grafting coating in gas-liquid membrane contactor: A comparative study

The gas-liquid membrane contactor (GLMC) is a new and promising kind of gas separation technique, but still exhibits limitations, especially in membrane performance. In order to solve the above problems, we fabricated and characterized novel OH/SiO2/PES composite membranes using gas phase hydrolysis and graft coating methods, respectively. In the preparation process, whether to use alkali to pretreat the membrane was used as an evaluation index. The CO2/CH4 separation performance was tested using the modified OH/SiO2/PES hollow fiber membrane as the membrane contactor in GLMC. In the experiment, we conducted a single factor experiment with diethanolamine (DEA) as the adsorbent to analyze the effect of the flow rate and concentration of DEA on the separation of CO2/CH4. The collected gas had a CH4 content of 99.92% and a CO2 flux of 10.1059 × 10-3 mol m-2 s-1 while DEA at a concentration of 1 mol/L was flowing at a rate of 16 L/h. The highest separation factor occurred at this moment, which was 833.67. Overall, the CO2/CH4 separation performance in GLMC was enhanced with the use of the fluorinated OH/SiO2/PES composite membrane.

Investigation of Oil-Water Separation on an F-SiO2/TiO2-Based Superhydrophobic/Superoleophilic Surface: Experiment Evaluation and MD Simulation

Experiment evaluation and mechanism analysis of separation performance are crucial for oily wastewater treatment. In this work, a fluorinated superhydrophobic/superoleophilic (F-SHPB/SOPL) surface was fabricated on a steel mesh substrate by double depositions of SiO₂-TiO₂ nanoparticles for high-roughness improvement and composite modification of fluorine-alkyl groups for low-energy achievement. Measurements of SEM, XPS, FTIR, laser scanning confocal microscope (LSCM), and excitation-emission matrix (EEM) were carried out for surface property characterization. The oil-water separation performances at the prepared F-SHPB/SOPL surface were investigated from experimental and simulation aspects. Separation tests, flux tests, and anti-contamination tests were performed by experimental methods. The results indicated that the surface showed excellent separation efficiencies (>99.2%) for oil-water mixture and oil-in-water emulsion, high permeate flux (>3000 L·m^-2·h^-1) for organic oils, and perfect anti-pollution/self-cleaning capacity for liquid and solid contaminations. The interaction energies and interaction distances were measured by ab initio molecular dynamics simulation (AIMD) simulations. With lower interaction energy (E_oil = -456.52∼-1044.22 eV) than that of water molecules (E_water = -172.73 eV) and shorter distance (D_oil = 4.42∼5.13 Å) than that of water molecules (D_water = 11.49 Å), oil molecules showed higher interaction stability than water molecules on the F-SHPB/SOPL surface. The calculation revealed the essence of the oil-water separation phenomenon. This work not only proposes the fabrication methodology of the SHPB/SOPL material but also elucidates the intermolecular interaction for oil-water separation. The results can provide a fundamental basis for separation operation and removal treatment in industrial and domestic applications.

Superhydrophobic Surface-Constructed Membrane Contactor with Hierarchical Lotus-Leaf-Like Interfaces for Efficient SO2 Capture

An organic-inorganic polyvinylidene fluoride/polyvinylidene fluoride-silica (PVDF/PVDF-SiO₂) mixed matrix membrane contactor is fabricated via a facile and efficient hydrophobic modification method. The solubility parameters of the PVDF particle are precisely regulated, the PVDF particles are blended with SiO₂ nanoparticles to form PVDF-SiO₂ suspension, and then the suspension is introduced onto the surface of the PVDF substrate by an in situ spin coating strategy. The PVDF particles are partly etched and incorporated to construct the adhesive PVDF-SiO₂ core-shell layer on the PVDF substrate, which results in a more stable PVDF-SiO₂ coating layer on the substrate. The surface structure is precisely regulated by changing the etching morphology of PVDF particles and amount of doped PVDF and SiO₂ particles, forming an integrated porous PVDF-SiO₂ layer and constructing hierarchical lotus-leaf-like interfaces. The resultant PVDF/PVDF-SiO₂ membrane contactors display the relatively regular distribution of pore size with ∼420 nm and excellent hydrophobic property with a water contact angle of ∼158°, which noticeably lightens wetting phenomena of membrane contactors. The SO₂ absorption fluxes can reach as high as 1.26 × 10^-3 mol·m^-2·s^-1 using 0.625 M of ethanolamine (EA) as liquid absorbent. The high stability of the SO₂ absorption flux test indicates the excellent interface compatibility between the PVDF-SiO₂ coating layer and the PVDF substrate. The versatile organic-inorganic layer exhibits super hydrophobic property, which prevents wetting of membrane pores. In addition, the membrane mass transfer resistance (H/K_m) and membrane phase transfer coefficient (K_m) are explored.

Hydrophobic Magnetic Porous Material of Eichhornia crassipes for Highly Efficient Oil Adsorption and Separation

Many oil adsorption materials are composed of nonrenewable raw materials, and their disposal can increase resource consumption and cause new environmental pollution. In this paper, the carbonized Eichhornia crassipes (CEC) were immobilized with Fe₃O₄ magnetic nanoparticles and modified with 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (PFOS) to prepare an oil adsorption material, referred to here as CEC/Fe₃O₄/PFOS. The magnetic and mechanical strength of the CEC was enhanced by adding Fe₃O₄ magnetic particles, which enable it efficient to dispose the oil/water solution. CEC/Fe₃O₄/PFOS shows high porosity (83.53%), low skeletal density (0.487 g/cm³), excellent magnetism, ultrahigh oil absorption capacity (49.94-140.90 g/g), hydrophobic performances with a water contact angle of 150.1 ± 2.3°, and a sliding angle of 10.5°. It is worth noting that the material can be recycled, and the absorbed oil is obtained by distillation. Therefore, this work may provide a candidate for solving the problem of oil pollution using E. crassipes.