Toxicity assessment of multiwalled carbon nanotubes and fullerenes to Pseudokirchneriella subcapitata, Daphnia magna and Poecilia reticulata in simulated fresh water systems

Abstract: A huge variety of benefits are expected from the application of carbon based nanomaterials. Currently, the nanoproducts that can be found on the market can be classified as consumer products whereas future applications are presumed to encompass areas such as medicine, water purification and industrial applications. Nanomaterials are used mainly for their unique physicochemical properties which are known to improve products’ characteristics. Contrary to the physicochemical goodness, it is these very unique properties that have since raised health and the environmental concerns for. For the sustainability of this innovation and protection of the environment as well as human health, pro-active effort to understand and alleviate potential risks is vital. Current knowledge on nanoecotoxicology is clouded by uncertainties pertaining their fate and behaviour in the environment. With the increase in nanotechnology, carbon-based nanomaterials’ (CBN) have been earmarked for water purification. Their (CBN) behaviour in the aquatic environment, their biovailability in aquatic systems, interaction with and internalization by living organisms and their sub-lethal effects to aquatic organisms are key-determinates to their toxicity, yet they have only just began to emerge. The overarching aim of this thesis therefore was to address the existing gap in knowledge and further bring understanding of fate and behaviour of multi-walled carbon nanotubes (MWCNT) and fullerenes (C60) and their acute and sub-lethal toxicity to algae (Pseudokirchneriella subcapitata), daphnia (Daphnia magna) and fish (Poecilia reticulata) in simulated fresh water systems of varied salinity. The MWCNT and C60 were successfully synthesized using nebulized spray pyrolysis and chemical vapour deposition, respectively, as evidenced by characteristic peaks (D and G bands) identified using Raman spectroscopy. Acid oxidation of p-MWCNT and p-C60 yielded o-MWCNT and o-C60 respectively...Ph.D. (Chemistry