Reaction of Water-Stable C-60 aggregates with ozone
ABSTRACT While the reactivity of C60 has been described in a variety of organic solvents, little information is available regarding aqueous-based reactions due to solubility limitations. In this study, a reaction between C60, as a nanoscale suspension, and dissolved ozone in the aqueous phase was investigated. Findings indicate a facile reaction occurs, resulting in aggregate dissolution concurrent with formation of water-soluble fullerene oxide species. Product analyses, including 13C NMR, MS (LDI), FTIR, UV-Vis, and XPS, indicate highly oxidized fullerene with an average of approximately 29 oxygen additions per molecule, arranged in repeating hydroxyl and hemiketal functionalities. These findings are significant in that they (1) demonstrate the feasibility of other aqueous-based fullerene chemistries, including those for alternative synthesis routes, which might otherwise be considered prohibitive on the basis of solubility limitations, and (2) imply that the aqueous reactivity of fullerene-based materials must be considered appropriately for accurate assessment of their transport, fate, and potential risk(s) in environmental systems.
- SourceAvailable from: Xianji Tao[Show abstract] [Hide abstract]
ABSTRACT: Understanding sub-lethal effects of nanomaterial may be particularly important to determining ecosystem responses as current levels of nanomaterial release are low compared to levels projected for the future. In this work, the sub-lethal effects of water stable, nanocrystalline fullerenes as C60 (termed nC60) were studied on Scenedesmusobliquus, a globally distributed phytoplankton. Sub-lethal concentration for S. obliquus was firstly determined as 0.09mgL(-1) using the standard 72h exposure tests (OECD Guideline 201). Subsequent sub-lethal experiment of nC60 on the S. obliquus was carried out for 60d and focused on the photosynthesis processes. The results demonstrate that upon sub-lethal exposure, the photosynthetic products of polysaccharide, soluble protein and total lipid were decreased with exposure time. The photosynthetic pigments of chlorophyll a and chlorophyll b were negatively impacted. Further investigations indicate that the decrements in photosynthetic products and pigments were mainly due to the algal Mg(2+) decrement (by 40%) at the sub-lethal concentration (0.09mgL(-1)) of nC60. The decrement in Mg(2+) of S. obliquus was due to the inhibition of Mg(2+)-ATPase activity caused by nC60. Sum up, these results not only describe the sub-lethal effects but also provide the probably mechanism for sub-lethal effects of nC60 on exposed S. obliquus. Copyright © 2014 Elsevier Ltd. All rights reserved.Chemosphere 12/2014; 122. DOI:10.1016/j.chemosphere.2014.11.035 · 3.50 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: The environmental application and risk assessment of manufactured nanoparticles (MNPs) in soil greatly depend on our understanding of the interactions between MNPs and soil components. Because of the complexity of the soil system and the very early stage of MNP research in soil, our understanding of MNP behaviour in this system is very limited. This review summarizes the progress of research on MNPs and their implications for soils. Manufactured nanoparticles are applied deliberately for soil remediation and are also released unintentionally through various other pathways to soil. Their colloidal behaviour in the soil system is discussed by analysing the effect of dissolved organic matter, light irradiation, water chemistry conditions and biological processes. The methods currently used for modelling MNP leaching and transport are summarized and several requirements for model improvement are proposed. The current topics regarding the environmental risks of MNPs (such as identifying the toxicity of MNPs and their dissolved ions, evidence that MNPs may be taken up by soil organisms or the risks of other pollutants as affected by the presence of MNPs) are described. Future research directions are discussed and proposed.European Journal of Soil Science 08/2012; 63(4). DOI:10.1111/j.1365-2389.2012.01475.x · 2.39 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Ozone is a strong oxidizer that can kill bacteria and other micro- organisms very effectively. In the recent years, ozone has become very important for sterilization of water used in shrimp farming and treatment of wastewater from food industry. However, ozonisers available in the markets are very expensive and have low energy-efficiency. In this work, a highly- efficient and low-cost system that can produce high-concentrations of ozone gas and dissolved ozone in water has been developed. The system consists of a dried air unit, high-voltage rf power supply, ozoniser tubes and venturi injector. The tubes are designed and configured to convert oxygen gas to ozone gas by atmospheric surface glow barrier discharge.