Degradation Products from Consumer Nanocomposites: A Case Study on Quantum Dot Lighting

Abstract

Most nanomaterials enter the natural environment as nano-enabled products, which are typically composites with primary nanoparticles bound on substrates or embedded in liquid or solid matrices. The environmental risks associated with these products are expected to differ from those associated with the as-produced particles. This article presents a case study on the end-of-life emission of a commercial prototype polymer/quantum-dot (QD) composite used in solid-state lighting for homes. We report the extent of cadmium release upon exposure to a series of environmental and biological simulant fluids, and track the loss of QD-characteristic fluorescence as a marker for chemical damage to the CdSe/ZnS nanoparticles. Measured cadmium releases after 30-day exposure range from 0.007-1.2 mg/g of polymer, and the higher values arise for low-pH simulants containing nitric or gastric acid. Centrifugal ultrafiltration and ICP was used to distinguish soluble cadmium from particulate forms. The leachate is found to contain soluble metals with no evidence of free QDs or QD-containing polymeric debris. The absence of free nanoparticles suggests that this product does not raise nanotechnology-specific environmental issues associated with degradation and leaching, but is more usefully regarded as a conventional chemical product that is a potential source of small amounts of soluble cadmium.

Environmental release of core–shell semiconductor nanocrystals from free-standing polymer nanocomposite films

“…We note that our results are consistent with an earlier effort by Liu et al . 36 that utilized QD/acrylate polymer materials as a case study to assess the potential environmental exposure to nanoparticles from nanocomposite-based consumer products; however this prior work provides a different view of release mechanisms that our study offers, because it only investigated a single QD size and also focused predominantly on release of cadmium.…”

“…Several studies have focused on PNCs intended for food contact applications, 15-27 but release from nanocomposite textiles, 28-31 exterior paints, 32,33 biomedical devices, 34 and other consumer products 31,35,36 has also been evaluated. Release of silver nano-particles or residuals from PNCs has received a high amount of attention 15-22,27,31,35,37 due to the widespread interest in the antimicrobial properties of silver.…”

Suitability of analytical methods to measure solubility for the purpose of nanoregulation

“…UF is different from dialysis in that this is a pressure-driven process (through the use of a vacuum/centrifugal force), which leads to the separation across a semi-permeable membrane (Cheryan, 1998). The use of UF has been extensively applied to nanomaterials, and membranes with pore size in the range of 3-100 kDa (smaller than 1 nm) have been used to study the solubility/dissolution of (for example): silver (El Badawy et al, 2011;Fabricius et al, 2014;Hadioui et al, 2013;Liu et al, 2012a), zinc oxide (Fabricius et al, 2014;Sivry et al, 2014), cerium oxide (Cornelis et al, 2011;Fabricius et al, 2014), titanium dioxide (Fabricius et al, 2014), copper oxide (Wang et al, 2012), quantum dots (Liu et al, 2012a) and gold (Fabricius et al, 2014). One limitation in UF relates to potential interactions of the membrane not only with the nanomaterial but also with the dissolved species.…”

Detection, characterization and quantification of inorganic engineered nanomaterials: A review of techniques and methodological approaches for the analysis of complex samples

“…1 nm) are available. Thus free ionic species can be easily isolated from nanoparticles, whereas the separation of the corresponding complexes can be difficult depending on the molecular weight of the complexes and the size of the NPs [49,50]. Moreover, depending on their composition and surface functionality, ENMs and the corresponding dissolved species can show interactions with the membrane surfaces, affecting their recoveries [51].…”