Experimental eva‎luation of self-cleaning surfaces with hydrophobic and hydrophilic fillers

5/13/2024 12:00:00 AM

The presence of external factors such as pollution of organic and inorganic substances on man-made structures leads to the fact that the performance, efficiency and costs of the repair and maintenance of these structures increase significantly. Shark skin, butterfly wings, leaves of plants like lotus have a special structure that prevents external factors from sitting on the surfaces of these structures, and these structures create properties in these surfaces that are known today as self-cleaning coatings. These coatings are divided into hydrophilic photocatalyst and hydrophobic. Each of these coatings has advantages and disadvantages that cannot be used in every environment. Nowadays, many researches are being done in the field of self-cleaning coatings in order to improve the performance of these coatings. Designing a photocatalyst hydrophobic self-cleaning surface that has both hydrophobic and photocatalytic benefits has attracted much attention in recent years. Since self-cleaning surfaces containing TiO2 create limitations for these surfaces due to the release of free radicals, using a method to create a photocatalyst superhydrophobic surface without damaging the photocatalytic properties of TiO2 has always been desired by many researchers. One of the existing theories to create such surfaces is creating hierarchical roughness on the surface. In this research, by using of electrostatic spray method, a photocatalyst superhydrophobic surface with micro-nano hierarchical roughness was made by combining FEP resin and SiO2 and TiO2 fillers with a static contact angle of 153 and a hysteresis angle of less than 5˚. This superhydrophobic surface containing nano silica content 12 wt% and TiO2 20 wt% exhibited excellent photocatalytic activities in the organic materials degradation. The obtained photocatalyst surfaces also revealed proper stability in acidic (pH = 5) and alkaline (pH = 11) media. Moreover, a suitable stability was observed in the fouling medium with duration 10 h while no change in the static contact angle occurred. Since simulation of the self-cleaning behavior of these coatings is effective in eva‎luation of their performance, part of this research has been used to numerically investigate the movement of droplet on self-cleaning surfaces using the volume of fluid method and the use of the slipping boundary condition to determine the amount of sliding and rolling of the droplet. The results show that small droplets have a higher rolling speed than larger droplets because their radius is smaller than the capillary length. Also, smaller droplets have a higher sliding speed than larger droplets at a fixed slipping length. In addition, increasing the slipping length leads to a decrease in its rolling speed.

خود تميز شونده , فتوكاتاليست , اسپري الكترواستاتيك , غلتش , آب گريز

Superhydrophobic , Photocatalytic , Self-cleaning , Electrostatic spray , Rolling

ali ansari

nowroz mohammad nouri