Abstract:
Following the huge growth in nanotechnology-related industries, significant concerns have arisen about their impact on both human health and the environment. As commercial exploitation of engineered nanomaterials (ENMs) continues to expand, it is increasingly urgent to understand, reduce and, where possible, to eradicate, potential negative environmental impacts and ultimately control their safety to the environment.
There are several pathways for ENMs to enter the environment depending on their application, e.g. ENMs released from paints or fabrics during the washing process are predicted to end up in landfill, soil, and surface waters, whereas for sunscreens, coatings, and cleaning agents, the major release of ENMs to the environment will be via sewage treatment plants. Zinc oxide (ZnO) has attracted a vast quantity of research owing to its wide range of optoelectronic and electrical properties. ZnO NPs are widely utilised in cosmetics, paints, personal hygiene products, sunscreens and moisturizers, and also used as antibacterial agents in ointments, lotions and surface coatings to prevent microorganism growth
In this work, we aim to quantify the lifetime of ENMs, and to characterise their physicochemical characteristics as they reach the environment through sewage and wastewater treatment. We hypothesise that the ZnO ENMs nanomaterials will transform in these media and these subsequent physico-chemical alterations will change the bioreactivity of the nanomaterials to biota and bacteria. In the aquatic environment for example, ionic zinc may partition and sorb to sediments or suspended solids in surface waters, and may sorb on to clay minerals, and organic material.
ZnO ENMs with highly controlled morphologies were synthesised following a procedure described by Xie et al. [1] and Wang et al. [2]. Physicochemical properties (i.e. shape, size distribution, agglomeration state, crystal structure bulk and surface chemistry) and concentrations of the selected ENMs after their incubation in a range of synthetic and environmental waters are being characterised using a range of both conventional bulk and spatially resolved techniques (i.e. high resolution EM, XRD, DLS, ICP-OES, etc). Finally, I will present data using new in situ synchrotron techniques to track dissolution and changes in the aggregation state as well as to evaluate the Zn speciation in the environment.
This work has been financially supported by project MMRE_P57561 from the Natural Environment Research Council.
1. Xie, F., et al., Tunable synthesis of ordered Zinc Oxide nanoflower-like arrays. Journal of Colloid and Interface Science, 2013. 395: p. 85-90.
2. Wang, T., et al., Broadband enhanced fluorescence using zinc-oxide nanoflower arrays. Journal of Materials Chemistry C, 2015. 3(11): p. 2656-2663.