Multifunctional silanized ZnO/SiO2/carbon black nanocomposite for enhanced photocatalytic degradation and oil–water separation

Abstract Ensuring universal access to clean water continues to be a pressing challenge worldwide. In this research, carbon black and zinc oxide nanoparticles were chemically activated using a mixture of sulfuric acid and potassium permanganate (KMnO4) to enhance their surface reactivity. Following this treatment, a sol–gel synthesis approach was applied to produce hybrid nanostructures composed of zinc oxide (ZnO), SiO2, and carbon black. These hybrids were then surface silanized using two different silane agents (i.e., vinyltriethoxysilane (VTES) and bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT)) at a concentration of 5%. A suite of advanced techniques was employed to characterize the materials, including XPS, FTIR, TGA, BET surface area measurements, and FE-SEM. The silanization process markedly improved the hydrophobic nature of the hybrids, with water contact angle (WCA) measurements rising from 21° to as high as 150°. Incorporating the functionalized hybrids led to a substantial decrease in the optical band gap to 2.8 eV, enhancing their photocatalytic efficiency. Mechanical testing revealed a significant boost in the reinforcement index for composites containing modified particles. Additionally, surface wettability assessments showed an increase in WCA from 91° to 151°, alongside a sharp drop in oil contact angle (OCA) from 52° to 12°, following silane treatment. These findings highlight the strong potential of silane-functionalized ZnO/SiO2/carbon black hybrids in developing multifunctional rubber nanocomposites for simultaneous oil–water separation and photocatalytic pollutant remediation.