Toxicity evaluation based on particle size, contact angle and zeta potential of SiO2 and Al2O3 on the growth of green algae

In this investigation, ecotoxicity of nano and micro metal oxides, namely silica (SiO2) and alumina (Al2O3), on the growth of green algae (Porphyridium aerugineum Geitler) is discussed. Effects of nano and micro particles on the growth, chlorophyll content and protein content of algae are analysed using standard protocols. Results indicate that SiO2 nano and micro SiO2 particles are non-toxic to P. aerugineum Geitler up to a concentration of 1000 mg/L. In addition, Al2O3 microparticles are less toxic to P. aerugineum Geitler, whereas Al2O3 nanoparticles are found to be highly toxic at 1000 mg/L. Moreover, Al2O3 nanoparticles decrease the growth, chlorophyll content, and protein content of tested algae. In addition, zeta potential and contact angle are also important in enhancing the toxicity of metal oxide nanoparticles in aquatic environment. This study highlights a new insight into toxicity evaluation of nanoparticles on beneficial aquatic organisms such as algae.