Avalanche effect for chemically modified dust mitigation from surfaces

Abstract

Cost effective dust mitigation from surfaces is one of the challenges in various sectors. The reduction of dust adhesion on surfaces plays a vital role for dust mitigation from surfaces under the gravitational influence. Creating an avalanche effect on dusty surfaces improves the dust mitigation rate and provides an effective cleaning process. Hence, solution treatment of dust by low concentration hydrofluoric acid is considered towards reducing dust adhesion on glass surfaces. To increase the rate of dust mitigation, the avalanche influence is created by the higher density and larger size particles (5300 kg/m3 and ~ 50 µm) than the average size dust particles (2800 kg/m3 and 1.2 µm) via locating them in the top region of the dusty glass surfaces. Mitigation velocity of the dust particles is evaluated using a high-speed recording system and the tracker program. Findings revealed that solution treatment (curing) of the dust particles results in the formation of fluorine compounds, such as CaF2 and MgF2, on dust surfaces, which suppress dust adhesion on surfaces. OSHA Globally Harmonized System lists the fluorine compounds formed as environmentally non-harmful. Avalanche's influence results in dust mitigation at a smaller tilt angle of the glass surface (~ 52°) than that of the case with none-avalanche influence (63°). Area cleaned on the glass surface, via dust mitigation, is larger as the avalanche is introduced, which becomes more apparent for the solution treated dust particles. Dust mitigation under avalanche influence improves optical transmittance of the dusty glass samples by a factor of 98%.

Impacting Water Droplets Can Alleviate Dust from Slanted Hydrophobic Surfaces

“…, 33 where r corresponds to the roughness parameter, which is about 0.62 for the dust particles. 2,26 The interfacial resistance can be estimated as γ s − L =2.1 mJ/m 2 for water, which is similar to the data presented. 26 Hence, water wets the dust surface (S>0).…”

“…The dust surface free energy is found to be 112.5 ± 8 mJ/m 2 , which is similar to the that reported earlier. 2 Therefore, the spreading factor for water can be obtained from: 33,34 However, the interfacial tension between water can be determined from…”

“…1 Hydrophobic states become favorable because of the small pinning force created between the surface and the particles such as environmental dust. 2 Water droplet motion enables cleaning via mitigating of the particles from the dusty hydrophobic surfaces. However, several challenges are encountered during dust mitigation by rolling water droplets.…”

“…Small-size dust particles strongly attach to the surfaces, and their removal by rolling droplets or gravitational acceleration becomes extremely difficult. 2 The force created by the combination of the impacting droplet and gravity on the inclined surfaces can improve dust mitigation rates from the surfaces. Hence, investigation of droplet impact and dust mitigation from slanted hydrophobic surfaces becomes essential.…”

“…Surface characteristics are critically important for self-cleaning applications . Hydrophobic states become favorable because of the small pinning force created between the surface and the particles such as environmental dust . Water droplet motion enables cleaning via mitigating of the particles from the dusty hydrophobic surfaces.…”