Liquid wettability of solid substrates is an important part of environmental chemistry and materials engineering used in industrial and academic research. A recent study published in the journal Research in industrial and engineering chemistry focuses on the creation of sustainable superhydrophobic coating materials using nanofluids based on readily available materials such as silica (SiO2) nanoparticles.
Study: Tuning of wetting properties of SiO2-based nanofluids in order to create durable surfaces with special wettability for self-cleaning, protection against pollution and oil and water separation. Image credit: Fred Mantel / Shutterstock.com
The importance of wettability control of porous surfaces
Surfaces with increased wettability are widely used. Regulation of water absorption by porous surfaces such as rocks and granite has become a major research concern due to the natural absorption of fluids into porous materials.
Wettability can significantly affect pore flow characteristics and related macroscopic multiphase characteristics of the rock-fluid system. These include capillary forces, relative porosity, displacement efficiency, and multiphase liquid saturation.
As a result, the multiphase fluid properties of the rock formation can be controlled by modifying the hydrophilicity of the reservoirs in a specific manner.
Water blocking: A big productivity problem
Water ingress into hydrophobic rock formations during hydraulic cracking can cause water clogging. Numerous gas wells in oil or gas tanks experience serious productivity losses due to fluid clogging near the drilling area.
This process, called condensate clogging, occurs when the pressure in the tank drops below the condensation point due to depletion of the tank as gas extraction continues.
Problems with water blocking and fluid accumulation can be alleviated by changing the hydrophilicity of the stones in the tank from water wetting to superhydrophobic, which leads to an effective increase in gas extraction.
The hydrophilicity of the reservoir stones is still being adjusted in order to achieve all the important properties, such as self-cleaning and anti-fouling ability and suitable thermodynamic and physical inertness. In addition, it is still a critical issue for industrial engineers to reduce oil barriers in the gas shelter of oil fields, which is due to the high oleophobicity of the rocks in the fields.
Improper dispersion of oil and water mixtures
With the rapid progress of industrialization, huge quantities of oil and water mixtures are now being produced worldwide in the oil, agricultural, pharmacological and other industries. Improper disposal of such waste poses a serious risk of environmental contamination.
Traditional techniques such as membrane insulation, electrocoalescence, gas buoyancy, sedimentation and hydrocyclone insulation are widely used to separate insoluble oil-water mixtures.
However, these approaches have significant limitations, such as limited separation efficiency, high costs, additional pollution, etc., which severely limits their use and encourages scientists to develop improved techniques, such as nanofluids, for oil and water separation.
Development of new wetting surfaces using SiO2Nanofluids based
This study investigated the wetting properties of three different ultra-repellent nanofluids made from polydimethylsiloxane (PDMS) modified SiO2 nanoparticles. Silicon dioxide (SiO2) nanostructures have large contact areas and show natural surface reactivity, which allows direct chemical changes.
PDMS, a hydrophilic viscoelastic silicone polymer, chemically modifies nanoparticles to provide strong water-repellent activity, mechanical resistance and thermodynamic stability. The researchers created superhydrophobic coatings on various substrates using SiO2 nanoparticles and PDMS.
In this work, the coating was applied using a simple and inexpensive approach by immersion in the solution. Meanwhile, X-ray diffraction (XRD), emission scanning electron microscopy (FESEM), and atomic force morphology (AFM) have investigated the surface chemistry, structure, and abrasion of coated rock samples.
Key research development
Nanofluid coatings exhibited prominent multidimensional properties, such as excellent repellent activity, low slip angle, exceptional self-cleaning and effective contamination protection. After contact with the substrate, a drop of water discharged from one cm through the water-repellent coating easily bounced off and slipped.
This improved liquid repellency is due to lower surface energy molecules and the construction of a layered nano-submicron architecture conducive to the formation of air pockets on the coating surfaces.
The use of a coating material on the surface of the netting has led to an efficient separation of the various oil and water mixtures. All of the above advantages, together with the strong physicochemical stability and barrier properties of the coated surfaces, suggest that the multifunctional coatings produced have many promises in several practical and commercial applications.
Esmaeilzadeh, P. et al. (2022). Tuning the wetting properties of SiO2-based nanofluids in order to create durable surfaces with special wettability for self-cleaning, pollution protection and oil and water separation. Research in industrial and engineering chemistry. Available at: https://pubs.acs.org/doi/10.1021/acs.iecr.2c00934
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