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 (KMnO 4 ) to enhance their surface reactivity. Following this treatment, a sol–gel synthesis approach was applied to produce hybrid nanostructures composed of zinc oxide (ZnO), SiO 2 , 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/SiO 2 /carbon black hybrids in developing multifunctional rubber nanocomposites for simultaneous oil–water separation and photocatalytic pollutant remediation.