The wettability of solid substrates by liquids is an important component of environmental chemistry and materials engineering used in industrial and academic research. A recent study published in the journal Industrial & Engineering Chemistry Research focuses on creating sustainable superhydrophobic coating materials using nanofluids based on easily accessible materials such as silica (SiO2) nanoparticles.
Study: Adjustment of the wetting properties of SiO2-based nanofluids to create durable surfaces with special wettability for self-cleaning, antifouling and oil and water separation. Image credit: Fred Mantel / Shutterstock.com
Importance of controlling the wettability of porous surfaces
Surfaces with improved wettability have a wide range of uses. Regulation of water absorption from porous surfaces such as rocks and granite has become a major research interest due to the natural absorption of fluids into porous materials.
Moisture can significantly affect the pore-scale flow characteristics of a rock fluid system and the associated multi-phase macroscopic level characteristics. These include capillary forces, relative porosity, displacement efficiency, and multiphase fluid saturation.
As a result, the properties of the multiphase fluid of a rock formation can be controlled by modifying the hydrophilicity of the reservoirs in a specific way.
Water blockage: a major productivity challenge
Water incursion during hydraulic cracking in hydrophobic rock formations can cause water blockage. Numerous gas wells in oil or gas reservoirs experience severe productivity losses due to liquid clogging near the drilling region.
This process, called condensate blockage, occurs when the pressure in the tank falls below the dew point due to the depletion of the tank as the extraction of gas progresses.
Water blockage and fluid bank difficulties can be mitigated by changing the hydrophilicity of the rocks from the water-wetting reservoir to superhydrophobic, leading to an effective improvement in gas extraction.
Modifying the hydrophilicity of tank stones to achieve such important attributes as self-cleaning and anti-fouling capabilities and proper physical and thermodynamic inertia is still a work in progress. In addition, alleviating the oil blockage in the gas cover of oil tank regions, which occurs due to the high eleophobicity of the tank rocks, is still a critical issue for industrial engineers.
Inadequate dissipation of oil-water mixtures
With the rapid advancement of industrialization, a huge amount of water and oil blends are now being produced worldwide by the oil, agriculture, pharmacology and other sectors. Improper disposal of this waste poses a serious risk of environmental pollution.
Traditional techniques such as membrane isolation, electrocoalescence, gas flotation, sedimentation, and hydrocyclone isolation have been widely used to separate insoluble mixtures of oil and water.
These approaches, however, have important limitations, such as limited separation efficiency, high cost, additional pollution, etc., which severely limit their use, and have encouraged scientists to create improved techniques, such as nanofluids. , for water-oil separation.
Development of new wetting surfaces using SiO2-based nanofluids
This study examined the wetting qualities of three different ultra-repellent nanofluids made of polydimethylsiloxane-modified SiO2 nanoparticles (PDMS). Silica nanostructures (SiO2) have large contact areas and exhibit natural surface reactivity, allowing for simple chemical alterations.
PDMS, a hydrophilic viscoelastic silicone polymer, chemically modifies nanoparticles to give strong water-repellent activity, mechanical strength and thermodynamic stability. The researchers created superhydrophobic coatings on various substrates using SiO2 and PDMS nanoparticles.
The coating was applied by the simple and economical solution immersion approach in this work. Meanwhile, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and atomic force morphology (AFM) examined surface chemistry, structure, and abrasion. of the coated rock samples.
Key research developments
Nanofluid coatings had outstanding multidimensional characteristics, such as superior liquid repellent activity, low sliding angle, exceptional self-cleaning, and effective antifouling. After coming into contact with the substrate, a drop of water thrown from a cm above the water-repellent cover bounced off easily and slipped.
This improved liquid repellency is due to the influence of lower surface energy molecules and the construction of a layered nano-submicro architecture conducive to the production of airbags on the coating surfaces.
The use of the coating material on a mesh surface resulted in the efficient separation of various mixtures of oil and water. All the advantages mentioned above, together with the strong physicochemical stability and barrier properties of the coated surfaces, suggest that the multifunctional coatings produced are very promising in various practical and commercial applications.
Reference
Esmaeilzadeh, P. et al. (2022). Adjustment of the wetting properties of SiO2-based nanofluids to create durable surfaces with special wettability for self-cleaning, antifouling and oil and water separation. Research in Industrial Chemistry and Engineering. Available at: https://pubs.acs.org/doi/10.1021/acs.iecr.2c00934
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