A study of the adsorption of titanium dioxide and zinc oxide nanoparticles on polyethylene microplastics and their desorption in aquatic media

Putar, Ula (author), Klun, Barbara (author), Marolt, Gregor (author), Imperl, Jernej (author), Kalčíková, Gabriela (author)

In this study, we investigated the interactions between titanium dioxide (nTiO$_2$) and zinc oxide (nZnO) nanoparticles and polyethylene microplastics (MPs) with respect to their adsorption and subsequent desorption in aquatic media. Adsorption kinetic models revealed rapid adsorption of nZnO compared to nTiO$_2$, while nTiO$_2$ was adsorbed to a greater extent – four times more nTiO$_2$ (67%) was adsorbed on MPs than nZnO (16%). The low adsorption of nZnO can be explained by the partial dissolution of zinc from nZnO in the form of Zn(II) and/or Zn(II) aqua-hydroxo complexes (e.g. [Zn(OH)]$^+$, [Zn(OH)$_3$]$^−$, [Zn(OH)$_4$]$^{2−}$), which were not adsorbed on MPs. Adsorption isotherm models indicated that the adsorption process is controlled by physisorption for both nTiO$_2$ and nZnO. The desorption of nTiO$_2$ was low (up to 27%) and not pH dependent, and only nanoparticles were desorbed from the MPs surface. On the other hand, the desorption of nZnO was pH dependent; at a slightly acidic pH (pH = 6), 89% of the adsorbed zinc was desorbed from the MPs surface and the majority were in the form of nanoparticles; at a slightly alkaline pH (pH = 8.3), 72% of the zinc was desorbed, but the majority were in the soluble form of Zn(II) and/or Zn(II) aqua-hydroxo complexes. These results demonstrated the complexity and variability of interactions between MPs and metal engineered nanoparticles and contribute to a better understanding of their fate in the aquatic environment.

• Language: English
• Keywords: microplastics, nanoparticles, metal nanoparticles, adsorption, desorption, isotherms, kinetics, freshwaters, nanomaterials
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: 10 str.
• Numbering: Vol. 888, art. 164163
• PID: 20.500.12556/RUL-146387
• UDC: 66:504.4:628.1
• ISSN on article: 1879-1026
• DOI: 10.1016/j.scitotenv.2023.164163
• COBISS.SI-ID: 153539331
• Publication date in RUL: 26.05.2023

Record is a part of a journal

• Title: Science of the total environment
• Publisher: Elsevier
• ISSN: 1879-1026
• COBISS.SI-ID: 23110917

Licences

• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.

Secondary language

• Language: Slovenian
• Keywords: mikroplastika, nanodelci, kovinski nanodelci, adsorpcija, desorpcija, površinske vode