Effect of modified ZnO nanoparticles synthesized via the sonochemical method on the self-cleaning behavior of a waterborne acrylic coating

In this research, the self-cleaning property of Al-doped ZnO nanoparticles prepared via the sonochemical method was investigated. The photocatalytic and hydrophilic activities of nanoparticles were studied while being applied as an additive into the waterborne acrylic resin-based coating. The influence of various doping amounts of Al with ZnO has been evaluated in terms of crystallographic structures, morphologies, optical properties, etc. using XRD, TEM, EDS, and UV-Vis analysis. Hexagonal and rod-like nanoparticles were revealed as the dominant morphology for the low and high dosage of doped Al, respectively. The photocatalytic activity of coating was studied using methyl orange by exposing them to ultraviolet (UV) irradiation. Results showed that acrylic coating with doped nanoparticles represented higher degradation, in comparison with the pure ZnO nanoparticles. The rate of degradation of 5% Al-doped nanoparticles was found to be higher than that of other samples. Furthermore, the hydrophilic property of the coating was determined by measuring the water droplet contact angle with the surface under UV irradiation. The results showed that the resin coating with doped nanoparticles represented a lower contact angle, compared to the pure ZnO nanoparticles. The least angle equal to 21 degrees was achieved at 7% Al-doped sample after 180 min UV irradiation. Kinetic studies showed that the degradation of methyl orange corresponds well with the first-order reaction.