Silica-Based Superhydrophobic and Superoleophilic Cotton Fabric with Enhanced Self-Cleaning Properties for Oil-Water Separation and Methylene Blue Degradation

Superhydrophobic textiles with multifunctional characteristics are highly desired and have attracted tremendous research attention. This research employs a simple dip-coating method to obtain a fluorine-free silica-based superhydrophobic and superoleophilic cotton fabric. Pristine cotton fabric is coated with SiO2 nanoparticles and octadecylamine. SiO2 nanoparticles are anchored on the cotton fabric to increase surface roughness, and octadecyl amine lowers the surface energy, turning the hydrophilic cotton fabric into superhydrophobic. The designed cotton fabric exhibits a water contact angle of 159° and a sliding angle of 7°. The prepared cotton fabric is characterized by attenuated total reflectance-fourier transform infrared spectroscopy, X-ray diffraction, atomic force microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. In addition, the coated fabric reveals excellent features, including mechanical and chemical stability, superhydrophobicity, superoleophilicity, and the self-cleaning ability. SiO2 nanoparticles and octadecylamine-coated cotton fabric demonstrate exceptional oil-water separation and wastewater remediation performance by degrading the methylene blue solution up to 89% under visible light. The oil-water separation ability is tested against five different oils with more than 90% separation efficiency. This strategy has the advantages of low-cost precursors, a simple and scalable coating method, enhanced superhydrophobicity and superoleophilicity, self-cleaning ability, efficient oil-water separation, and exceptional wastewater remediation performance.

Porphyrin-Based Nanomaterials for the Photocatalytic Remediation of Wastewater: Recent Advances and Perspectives

Self-organized, well-defined porphyrin-based nanostructures with controllable sizes and morphologies are in high demand for the photodegradation of hazardous contaminants under sunlight. From this perspective, this review summarizes the development progress in the fabrication of porphyrin-based nanostructures by changing their synthetic strategies and designs. Porphyrin-based nanostructures can be fabricated using several methods, including ionic self-assembly, metal-ligand coordination, reprecipitation, and surfactant-assisted methods. The synthetic utility of porphyrins permits the organization of porphyrin building blocks into nanostructures, which can remarkably improve their light-harvesting properties and photostability. The tunable functionalization and distinctive structures of porphyrin nanomaterials trigger the junction of the charge-transfer mechanism and facilitate the photodegradation of pollutant dyes. Finally, porphyrin nanomaterials or porphyrin/metal nanohybrids are explored to amplify their photocatalytic efficiency.

Coupled photocatalytic alkaline media as a destructive technology for per- and polyfluoroalkyl substances in aqueous film-forming foam impacted stormwater

The release of aqueous film forming foam (AFFF) from fuel fire events, fire training events, and other activities has resulted in the presence of persistent and recalcitrant per- and polyfluoroalkyl substances (PFAS) in soil and water nationwide. This study describes the degradation and defluorination of PFAS in stormwater collected from an AFFF-impacted site. Silica-based granular media (SGM) containing titanium dioxide was packed into a column reactor and placed between ultraviolet (UV) lamps to excite the photocatalyst within the SGM and generate free radicals to degrade PFAS present in water that was passed through the media. The system was amended with nucleophiles (hydroxyls) to facilitate the destruction of PFAS. Results showed rapid degradation of 17 identified PFAS, including perfluoroalkyl acid (PFAA) precursors, perfluorosulfonic acids (PFSAs), and perfluorocarboxylic acids (PFCAs). Significant defluorination was observed, indicating PFAS destruction as a result of the coupled photocatalytic and nucleophilic attack. Column reactor experiment findings indicate SGM in the presence of UV light passively degraded a mixture of PFAS in a concentrated waste stream at ambient conditions.

Coordination framework materials fabricated by the self-assembly of Sn(IV) porphyrins with Ag(I) ions for the photocatalytic degradation of organic dyes in wastewater

Two porphyrin-based coordination frameworks, [Ag2(TPyP)Sn(OH)2](NO3)2●(solv)x (1) and [Ag2(TPyP)Sn(INA)2](OTf)2●(CH3CN)2 (2) (INA = isonicotinato anion, OTf = CF3SO3-), were constructed by the self-assembly of hexacoordinated (meso-tetra-(4-pyridyl)porphyrinato)Sn(IV) building blocks with Ag(I) ions. They...

Immobilization of TiO2 Nanoparticles in Cement for Improved Photocatalytic Reactivity and Treatment of Organic Pollutants

Non-point organic pollutants in stormwater are a growing problem in the urban environment which lack effective and efficient treatment technologies. Incorporation of conventional wastewater techniques within stormwater management practices could fundamentally change how stormwater quality is managed because contaminants can be degraded during stormwater transport or storage. This study investigated the photocatalytic reactivity of titanium dioxide functionalized with maleic anhydride (Ti-MAH) within cement pastes when compared to ordinary Portland cement. Preparation of Ti-MAH was performed by permanently bonding maleic anhydride to titanium in methanol, drying and powdering the residual material, and then inter-grinding the preparation with cement during mixing. When compared with OPC, the Ti-MAH cured cement paste is more reactive under a wider range of light wavelengths, possesses a higher band gap, sustains this heightened reactivity over multiple testing iterations, and treats organics effectively (>95% methylene blue removal). Amorphous silica within calcium-silica-hydrate, C-S-H, is theorized to bond to the powdered Ti-MAH during curing. Verification of silicon bonding to the titanium by way of MAH was demonstrated by FTIR spectra, SEM imagery, and XRD. Creating a sustainable and passive photocatalytic cement that precisely bonds silica to Ti-MAH is useful for organic contaminants in urban stormwater, but use can translate to other applications because Ti-MAH bonds readily with any amorphous silica such as glass materials, paints and coatings, optics, and LEDS, among many others.