Novel triangular silver nanoparticle modified membranes for enhanced antifouling performance

Abstract

This study marks the first ever attempt at the successful fabrication of a novel reactive membrane to combat fouling through layer-by-layer (LBL) surface modification with polyelectrolyte (PE), followed by anisotropic triangular silver nanoparticles (TSNP). The morphology and the presence of TSNP on the membrane was confirmed by HR-TEM, FE-SEM and XPS. The charge density of the novel membrane (PE-TSNP) was increased 15.6 fold, as a result of the sharp-tip morphology of the TSNP forming tip-based "hot spots" on the membrane surface and high-atom-density active facets, which also enhanced the membrane hydrophilicity by 36%. Owing to these improved features, the novel membrane displayed remarkable antibacterial and anti-adhesion properties by achieving 100% bactericidal effect against high initial bacterial concentration (10 7 CFU mL À1 ). The membrane flux was improved by 31% while retaining a high flux recovery rate of 98.2% against biofouling. The membrane also mitigated organic and bio-organic fouling by maintaining high flux recovery rates of 96% and 95% respectively. As compared with a spherical silver nanoparticle modified membrane (PE-SSNP), the PE-TSNP membrane was 25.7% more hydrophilic and achieved 10% higher bacterial killing. Moreover, the novel membrane displayed 9.5%, 11.6%, and 14% higher flux recovery rates than that of the PE-SSNP membrane against biofouling, organic and bio-organic fouling respectively. Furthermore, the novel membrane retained a long-term biocidal capability of 93% even after 4 months of successive tests. ICP-MS revealed silver ion leaching of 4 mg L À1 and the total silver loss of 14% from the PE-TSNP membrane after 14 days. Fig. 1 (a) Absorption spectrum of spherical silver nanoparticles and triangular silver nanoparticles. (b) HR-TEM image of the triangular silver nanoparticles. The inset shows the morphology of the single triangular silver nanoparticle. (c) XRD spectra of TSNP. Planes at {111}, {200}, {220} indicates face-centered cubic (fcc) lattice structure of crystalline Ag. (d) Shows the XPS spectrum of the PE-TSNP2 modified membrane. Distinct Ag3d peaks indicating the presence of Ag on the membrane surface. This journal isFig. 7 Long-term membrane performance (a) antibacterial rate of the PE-TSNP2 modified membranes against E. coli. (b) FE-SEM image of PE-TSNP2 membrane after fouling in long-term studies, showing the presence of triangular silver nanoparticles on the membrane.This journal is

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“…The modified membrane also poses an enhanced flux of 36% and high flux recovery of up to 96%. Moreover, the modification with silver nanoparticles with a triangle shape gives long-term membrane stability for up to 4 months of usage [43].…”

Enhanced Fouling Resistance and Antimicrobial Property of Ultrafiltration Membranes Via Polyelectrolyte-Assisted Silver Phosphate Nanoparticle Immobilization

“…Furthermore, the SEM image of the surface of the virgin membrane showed the presence of rod-shaped bacteria ( Figure 12 a), which were not observed on the AgPNP embedded membrane surface. The visible particles ( Figure 12 b) on the modified membrane resembled the immobilized AgPNPs that are shown in Figure 4 c. This clearly demonstrates that the PAH/PAA BL assisted AgPNP immobilization imparted the antimicrobial property to the UF membrane, implying less activity [ 76 ] and attachment of microorganisms that initiate the multi-step process of biofilm formation on the membrane surface [ 77 ]. A previous study by Liu et al [ 78 ], who tested a Ag-loaded chitosan/cellulose acetate blended membrane, suggested that functionalizing an anti-adhesive membrane surface with anti-microbial property was an effective way of providing anti-biofouling performance when compared to the approach of killing/inactivating the bacteria after attachment to the membrane surface.…”

Complex organic fouling and effect of silver nanoparticles on aquaporin forward osmosis membranes

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