Plasma deposition of silver nanoparticles on ultrafiltration membranes: Antibacterial and anti-biofouling properties

Abstract

A novel and versatile plasma reactor was used to modify Polyethersulphone commercial membranes. The equipment was applied to: i) functionalize the membranes with low-temperature plasmas, ii) deposit a film of poly(methyl methacrylate) (PMMA) by Plasma Enhanced Chemical Vapor Deposition (PECVD) and, iii) deposit silver nanoparticles (SNP) by Gas Flow Sputtering. Each modification process was performed in the same reactor consecutively, without exposure of the membranes to atmospheric air. Scanning electron microscopy and transmission electron microscopy were used to characterize the particles and modified membranes. SNP are evenly distributed on the membrane surface. Particle fixation and transport inside membranes were assessed before- and after-washing assays by X-ray photoelectron spectroscopy depth profiling analysis. PMMA addition improved SNP fixation. Plasma-treated membranes showed higher hydrophilicity. Anti-biofouling activity was successfully achieved against Gram-positive (Enterococcus faecalis) and -negative (Salmonella Typhimurium) bacteria. Therefore, disinfection by ultrafiltration showed substantial resistance to biofouling. The post-synthesis functionalization process developed provides a more efficient fabrication route for anti-biofouling and anti-bacterial membranes used in the water treatment field. To the best of our knowledge, this is the first report of a gas phase condensation process combined with a PECVD procedure in order to deposit SNP on commercial membranes to inhibit biofouling formation.

Electrochemical Signature of Escherichia coli on Nickel Micropillar Array Electrode for Early Biofilm Characterization

“…Following centrifugation at 6000 rpm for 5 min at 23 °C, the pellet formed was washed with PBS three times to eliminate residual nutrients and impurities. The cells were then re‐suspended in fresh LB at OD 600 =0.4 to ensure the homogeneity of the culture and incubated again for 2.5 h at 37 °C. After that, the biomass was centrifuged and washed as described earlier.…”

Protection of polymeric membranes with antifouling surfacing via surface modifications

“…The improvement of PMMA membrane film by plasma enhanced chemical vapor deposition (PECVD) and Ag nanoparticles was deposited by gas flow sputtering [58]. The treated plasma membrane showed an improved hydrophilic membrane surface.…”

Investigation of Biocidal Effect of Microfiltration Membranes Impregnated with Silver Nanoparticles by Sputtering Technique

“…It has been also described that, after long periods (e.g., more than 6 min) of plasma treatment, the surface of PES membranes can be damaged, for instance, the molecular bonds C-C and C-H can be cleaved by argon plasma. On the other hand, the application of short periods of time seams not affect the polymer chains of the membranes [ 43 , 44 ]. Therefore, in this current work, the FTIR spectra ( Figure S1 in Supplementary Materials ) of the membranes, before and after the impregnation of the nanoparticles, revealed no significant effects of the sputtering technique.…”