BACKGROUND: One of the main drawbacks of membrane processes is (bio)fouling. Recent attempts to overcome these phenomena focus on incorporation of nanoparticles into polymeric membrane matrices. This paper presents an investigation of the influence of modification of polyethersulfone (PES) ultrafiltration membranes with Ag/titanate nanotubes (Ag/TNTs) on physicochemical characteristics, water permeability and antifouling and antibacterial properties.RESULTS: The modified membranes were prepared via a wet phase inversion method by adding 0.1-1.5 wt% of Ag/TNTs relative to PES into the casting solution. An increase of water permeability with increasing Ag/TNTs content up to 1 wt% was found. The modification contributed to fouling mitigation during ultrafiltration of humic acids solution due to (i) improved hydrophilicity, (ii) presence of Ag/TNTs turbulence promoters and (iii) negative surface charge of the membranes. A correlation between membrane surface roughness, zeta potential and proneness to fouling is discussed. The highest inhibition of bacterial growth, reaching 99.8 and 99.3% for Escherichia coli and Staphylococcus epidermidis, respectively, was observed at the highest Ag/TNTs content. CONCLUSIONS:The introduction of Ag/TNTs into PES membrane structures improved membrane permeability, fouling resistance and antibacterial properties. The most significant improvement was observed in the case of membranes containing the largest quantities of Ag/TNTs. density of polyethersulfone (g mL −1 ) w density of water at 20 ∘ C (g mL −1 )

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Silver nanoparticles (NPs) are effective antibacterial agents; however, aggregation of NPs and uncontrolled release of Ag+ affect their efficiency and may pose a risk to the environment. To overcome these disadvantages, immobilization of Ag onto titanate nanotubes (TNTs) was investigated. This paper describes the physicochemical and antibacterial properties of silver incorporated titanate nanotubes (Ag/TNTs) prepared using five procedures and containing different Ag amounts (0.11–30.85 wt.%). The methods were (i) sol-gel followed by a hydrothermal process; (ii) photodeposition under ambient conditions; (iii) photodeposition under an inert atmosphere; (iv) NaBH4 reduction; and (v) electroless deposition after activation of TNTs with Sn2+. Depending on the synthesis procedure, the presence of metallic Ag NPs, AgO or AgCl was observed. The electroless method led to an additional deposition of SnO2 NPs. The antibacterial properties of Ag/TNTs were analyzed as a function of Ag content and released against Escherichia coli and Staphylococcus epidermidis. The best bactericidal properties exhibited Ag/TNTs prepared through the photodeposition process due to the higher interaction of exposed Ag NPs with bacteria. An increase of Ag loading resulted in improvement of antibacterial activity of Ag/TNTs although no direct correlation between silver content or release and inhibition of bacterial growth was found.

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