Toward Understanding the Environmental Risks of Combined Microplastics/Nanomaterials Exposures: Unveiling ZnO Transformations after Adsorption onto Polystyrene Microplastics in Environmental Solutions

Abstract

Over recent decades, there has been a dramatic increase in the manufacture of engineered nanomaterials, which has inevitably led to their environmental release. Zinc oxide (ZnO) is among the more abundant nanomaterial manufactured due to its advantageous properties, used for piezoelectric, semiconducting, and antibacterial purposes. Plastic waste is ubiquitous and may break down or delaminate into smaller microplastics, leaving open the question of whether these small polymers may alter the fate of ZnO through adsorption within aquatic media (tap‐water and seawater). Here, scanning electron microscopy analysis confirms the effective Zn nano/microstructures adsorption onto polystyrene surfaces after only 24‐h incubation in the aquatic media. After pre‐aging the nanomaterials for 7‐days in different environmental media, nanoprobe X‐ray absorption near‐edge spectroscopy analysis reveals significant ZnO transformation toward Zn‐sulfide and Zn‐phosphate. The interaction between a commercial ZnO‐based sunscreen with polystyrene and a cleanser consumer containing microbeads with ZnO nanomaterials is also studied, revealing the adsorption of transformed Zn‐species in the microplastics surfaces, highlighting the environmental relevancy of this work. Understanding the structural and functional impacts of the microplastics/ZnO complexes, and how they evolve, will provide insights into their chemical nature, stability, transformations, and fate, which is key to predicting their bioreactivity in the environment.

A critical review on the toxicity regulation and ecological risks of zinc oxide nanoparticles to plants

“…As an example, heavy metals, humic substances, and acetic acid in leachate affect the aggregation, electrostatic adsorption, and ion release of ZnO NPs, especially Cr( iii ) ions binding to hydroxyl groups on ZnO to generate ZnO–O bonds. 113 In addition to the combined exposure of multiple nanomaterials, 114 ZnO NPs can also adsorb with microplastics 115 but are limited by Zn 2+ , 116 as well as stimulate surface oxidation and degradation of microplastics. 117 Considering that ZnO NPs can act as both bioregulator products and exogenous nano-pollutants, the unknown risks to plants induced by exposure to multiple systems may be either toxicity mitigation or toxicity exacerbation (Table 1), implying that the field needs to be supported by more adequate research in the future.…”

Atomic spectrometry update: review of advances in elemental speciation

“…Lastly the behaviour of nano/microplastics as a vector of organic and metal contaminants is an active area of work as micro/nanoplastics can adsorb chemical compounds in their heterogeneous surface. In this line, Gomez-Gonzalez et al 147 evaluated the adsorption of ZnO NPs to microplastics under different environmental conditions (tap water, sea water and artificial seawater without DOM). The procedure was applied not only to suspensions of ZnO NPs (80–200 nm) and polystyrene microplastics standards (200 nm) but also to commercial sunscreen containing ZnO and an exfoliating cleanser containing microbeads.…”