Wettability alteration from superhydrophobic to superhydrophilic via synthesized stable nano-coating

In this study, synthesized TiO2/SiO2 hybrid nanoparticles were used to fabrication of hydrophilic coating with high stability on superhydrophobic surface of carbonate rock. For this purpose, n-heptane droplet contact angle in water medium was measured on the rock surface before and after treatment. The TiO2/SiO2 nanoparticles were synthesized by modified sol-gel method. This method is based on increasing functional groups on the surface of the TiO2 nanoparticles to produce high hydrophilic nanoparticles. The synthesized nanoparticles were characterized by Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses. The chemical composition and morphology of untreated and treated rock surface were determined using XRD and SEM analyses. It was observed that the n-heptane droplet was instantly spread on the untreated rock and its contact angle in water medium was 0°, in the other hand the water contact angle in n-heptane medium was 168°, so the un-coated rock was superhydrophobic. After adsorption of nanoparticles on the rock surface, the n-heptane droplet contact angle changed to 165° and the water contact angle changed to 0° so the coated rocks were superhydrophilic. The fabricated nano-coatings exhibited high thermal stability and moderate mechanical stability; also the coated surfaces had high stability in contact with salt solution, the results were encouraging. Applications of these nano-coatings include surfaces where cleanliness is paramount such as in hospitals as well as the maintenance of building facades and protection of public monuments from weathering. Novel industrial application includes wettability alteration of oil wet carbonate rock for enhanced oil recovery (EOR).