CNR ExploRA

Articolo in rivista, 2023, ENG, 10.3390/nano13222970

Polymeric Membranes Doped with Halloysite Nanotubes Imaged using Proton Microbeam Microscopy

G. Vasco, V. Arima, S. Boudjelida, M. Carraro, M. Bianco, A. Zizzari, E. Perrone, F. Galiano, A. Figoli, M. Cesaria

CEDAD--Center of Applied Physics, Dating and Diagnostics, Cittadella della Ricerca, University of Salento, SS. 7, Km. 7300, 72100 Brindisi, Italy; Department of Mathematics and Physics "Ennio De Giorgi", University of Salento, Campus Ecotekne, 73100 Lecce, Italy; CNR NANOTEC--Institute of Nanotechnology, c/o Campus Ecotekne, 73100 Lecce, Italy; Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy; Department of Material Sciences, University Mohamed El Bachir El Ibrahimi, Bordj Bou Arreridj 34030, Algeria; Institute on Membrane Technology (CNR-ITM), University of Padova, Via Marzolo 1, 35131 Padova, Italy Institute on Membrane Technology (CNR-ITM), Via P. Bucci 17/c, 87036 Rende, CS, Italy

Polymeric membranes are useful tools for water filtration processes, with their performance strongly dependent on the presence of hydrophilic dopants. In this study, polyaniline (PANI)-capped aluminosilicate (halloysite) nanotubes (HNTs) are dispersed into polyether sulfone (PES), with concentrations ranging from 0.5 to 1.5 wt%, to modify the properties of the PES membrane. Both undoped and HNT-doped PES membranes are investigated in terms of wettability (static and time-dependent contact angle), permeance, mechanical resistance, and morphology (using scanning electron microscopy (SEM)). The higher water permeance observed for the PES membranes incorporating PANI-capped HNTs is, finally, assessed and discussed vis-à-vis the real distribution of HNTs. Indeed, the imaging and characterization in terms of composition, spatial arrangement, and counting of HNTs embedded within the polymeric matrix are demonstrated using non-destructive Micro Particle Induced X-ray Emission (?-PIXE) and Scanning Transmission Ion Microscopy (STIM) techniques. This approach not only exhibits the unique ability to detect/highlight the distribution of HNTs incorporated throughout the whole thickness of polymer membranes and provide volumetric morphological information consistent with SEM imaging, but also overcomes the limits of the most common analytical techniques exploiting electron probes. These aspects are comprehensively discussed in terms of practical analysis advantages.

Nanomaterials (Basel) 13 (2970)