Unlike most chemical treatment techniques, superhydrophobic filters utilized in physical separation techniques are environmentally friendly materials that are effective for liquid–liquid phase separations without the need for the use of specialized equipment. The use of superhydrophobic filters has attracted special attention due to their unique surface properties, including low surface energies and self-cleaning capacity toward high separation efficiency between oil and water. The challenges associated with effluent oil treatments using physical and chemical techniques as well as the complex nature of these effluents necessitate the design and development of functionalized filter materials capable of efficient and sustainable oil/water separation to remediate severe pollution incidents.
2 In cases of oil spills, the formation of organic films isolates the seawater from rapid oxygen exchange with the surrounding atmosphere while starving marine lives of the needed molecular oxygen sustenance. 1 Discharges from industrial wastewaters generate oil-based environmental eluents ( e.g., toluene) and water-soluble pollutants ( e.g., dyes) whose dispersion within the food chain are also detrimental to human health. Recent trends in human activities have led to frequent oil spills and waste disposals, and these have severely impacted on marine lives. However, CTF3 displayed with a recorded separation efficiency less than 90° after five filtration cycles. Both fabrics also retained percentage separation efficiencies over 90% for both chloroform–water and toluene–water mixtures. Coated fabrics with 30 mg TMOS/10 mg HMDS (CMF3) and 30 mg HMDS/10 mg TMOS (CTF3) exhibited optimal superhydrophobicity. In this study, coated superhydrophobic cotton fabrics revealed a higher static aqueous contact angle of more than 150° and sliding hysteresis angle of less than 5°.
Both sets of coated fabrics exhibited unique capacities for self-cleaning and oil–water separation as superhydrophobic filters due to (a) their low surface energy silylated hybrid polysiloxane chemical groups, (b) their highly reduced surface wettability and (c) nanopatterned surface morphologies. After characterization and testing, these coated fabrics demonstrated varying responses to harsh solvents and thermal conditions. Unlike HMDS with substituted silyl (Me 3Si) groups, TMOS consists of hydrolysable trimethoxy silyl ((MeO) 3Si) chemical groups that allowed for the formation of nanosilica with Si–O–Si linkages needed to foster stable coatings. The first coated fabric was prepared predominantly via trimethylsilyl modification using hexamethyldisilazane (HMDS) while higher amounts of trimethoxy(octadecyl)silane (TMOS) further enhanced the superhydrophobicity of the second coating matrix. A new facile approach for preparing two nonfluorinated hybrid organic–inorganic siloxane/polydimethylsiloxane nanocomposite coatings for cotton fabrics is presented using two distinct silylating agents.
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