Sustainable nanomaterials: the role of Cyrene in optimising carbon nanotubes dispersion and filtration efficiency

Roxana A Milescu; C Rob McElroy; Edward J Taylor; Peter Eaton; Paul M Williams; Richard Phillips; Thomas J Farmer; James H Clark

doi:10.3389/fchem.2024.1498279

Sustainable nanomaterials: the role of Cyrene in optimising carbon nanotubes dispersion and filtration efficiency

Front Chem. 2024 Dec 19:12:1498279. doi: 10.3389/fchem.2024.1498279. eCollection 2024.

Authors

Roxana A Milescu¹, C Rob McElroy², Edward J Taylor³, Peter Eaton^{2

4}, Paul M Williams⁵, Richard Phillips⁶, Thomas J Farmer⁷, James H Clark¹

Affiliations

¹ Circa Renewable Chemistry Institute, Department of Chemistry, University of York, York, United Kingdom.
² Department of Chemistry, School of Natural Science, University of Lincoln, Lincoln, United Kingdom.
³ Department of Biological and Life Sciences, School of Natural Science, University of Lincoln, Lincoln, United Kingdom.
⁴ The Bridge, University of Lincoln, Lincoln, United Kingdom.
⁵ Department of Chemical Engineering, Faculty of Science and Engineering, Swansea University Bay Campus, Swansea, United Kingdom.
⁶ Membranology Limited, Swansea, United Kingdom.
⁷ Green Chemistry Centre of Excellence, Department of Chemistry, University of York, York, United Kingdom.

Abstract

This study focuses on the fabrication and characterisation of single-walled carbon nanotube (SWCNT) buckypapers and polyethersulfone (PES) flat-sheet membranes using Cyrene, aiming toevaluate its efficacy as a green solvent for these applications. Pristine SWCNTs were dispersed inCyrene without surfactants and compared to N-Methyl-2-pyrrolidone (NMP) dispersions. Buckypapers were fabricated from these dispersions and characterised using Scanning ElectronMicroscopy (SEM), Atomic Force Microscopy (AFM), and infrared spectroscopy. Their performancewas tested in wastewater and oil-water emulsion filtrations and antimicrobial activity. PESmembranes incorporating SWCNTs were prepared using phase inversion and analysed via SEM,optical microscopy, and contact angle. Membrane properties and water permeability were assessed,and bacterial challenge tests evaluated antimicrobial activity. Cyrene enabled the dispersion ofSWCNTs at higher concentrations (0.038 mg mL⁻¹) compared to NMP (0.013 mg mL⁻¹). Transmission Electron Microscopy (TEM) analysis revealed that Cyrene effectively debundles SWCNTs, yielding better dispersion. Buckypapers fabricated with Cyrene demonstrated dense, uniform networks with enhanced surface smoothness and promising filtration performance for wastewater treatment and oil-water separation. PES membranes made with Cyrene exhibited well-organised finger-like structures, interconnected pores, superior porosity, and higher water permeability than NMP-based membranes. Incorporating SWCNTs further improved membrane performance. However, bacterial challenge tests indicated no significant antimicrobial activity. The findings highlight Cyrene's potential as a sustainable alternative to traditional solvents, offering improved material properties and filtration performance. Despite these advantages, further studies are necessary to address solvent residuals and long-term safety considerations, ensuring its suitability for broader applications.

Keywords: Cyrene; buckypaper; carbon nanotubes; filtration membrane; nanocomposite; nanofluid; renewable chemistry; sustainability.

Grants and funding

The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. The authors would like to thank the Circa Group for part-funding of this study through the RenewChem. The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article, or the decision to submit it for publication.