Inhibition of algae growth on HVDC polymeric insulators using antibiotic-loaded silica aerogel nanocomposites

Algae contamination has been observed on high-voltage direct current transmission (HVDC) polymeric insulators in tropical and subtropical areas, and this has an impact on the outdoor insulation performance. In this paper, the antibiotic 4,5-dicholoro-2-octyl-2H-isothiazolone-one (DCOIT) was chosen to be loaded onto the porous silica aerogel through sol-gel and dip-molding methods; the nanocomposites were mixed with base silicone rubber to prepare the antibiotic polymeric insulator. The algae inhibition properties of the insulators were characterized by the damaged membrane rate, photosynthesis rate (SAT) and chlorophyll-a density (Chl) of the algae cells. The results showed that the antibiotic insulators were free from algae colonization and that the extermination process could be completed within 21 days. During the antibiotic treatment process, the specimen surface stayed hydrophobic because of the water repellent property of nano silica. Meanwhile, due to its excellent dispersibility and electrical resistivity, the volume conductivity and surface conductivity were slightly increased in the initial period within insulation margins. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) of antibiotic-containing insulators was carried out, and the intermediate products in the treatment process were verified. After algae apoptosis, the functional group on the silicone rubber was returned to its initial condition before algae colonization. After application on-site for 1 year, the antibiotic-loaded insulators retained antibiological properties without algae spots upon their surfaces.