In Situ Reduction of Silver by Polydopamine: A Novel Antimicrobial Modification of a Thin-Film Composite Polyamide Membrane

Abstract

We report a facile method for the antimicrobial modification of a thin-film composite polyamide reverse osmosis (RO) membrane. The membrane surface was first coated with polydopamine (PDA), whose reducing catechol groups subsequently immobilized silver ions in situ to form uniformly dispersed silver nanoparticles (AgNPs) inside the coating layer. Agglomeration of AgNPs was not observed despite a high silver loading of 13.3 ± 0.3 μg/cm(2) (corresponding to a surface coverage of 18.5% by the nanoparticles). Both diffusion inhibition zone tests and colony formation unit tests showed clear antimicrobial effects of the silver loaded membranes on model bacteria Bacillus subtilis and Escherichia coli. Furthermore, the silver immobilized membrane had significantly enhanced salt rejection compared to the control PDA coated membrane, which is attributed to the preferential formation of AgNPs at defect sides within the PDA layer. This self-healing mechanism can be used to prepare antimicrobial RO membranes with improved salt rejection without scarifying the membrane permeability, which provides a new dimension for membrane surface modification.

Facile one-pot synthesis of silver nanoparticles encapsulated in natural polymeric urushiol for marine antifouling

“…In addition, when the antibacterial rate has reached 100%, the AgNPs content in the coating was lower than previously reported studies. 44 The excellent antibacterial properties exhibited in the coatings we have developed were actually the result of the synergistic antibacterial effect of AgNPs and urushiol.…”

A novel gravity-driven nanofibrous membrane for point-of-use water disinfection: polydopamine-induced in situ silver incorporation

“…Previous studies have reported that membranes incorporated with silver nanoparticles are capable of inactivating different types of bacteria effectively 19, 30, 32 . The bactericidal effect is mainly caused by release of silver ions, damages to cell membrane via direct contact and generation of reactive oxygen species 15, 33 .…”

“…Silver nanoparticles were immobilized onto cPAN membranes through a spontaneous reduction of silver ions in situ by PDA 32 . Typically, a cPAN coupon (diameter of 7.6 cm) was immersed into a silver nitrate solution (0.5, 1.0, or 1.5 g/L) for 5.0 h. The silver ions were reduced by the catechol groups in the PDA chain.…”

Current Advances in Biofouling Mitigation in Membranes for Water Treatment: An Overview

“…In recent years, various porous nanomaterials were categorized as a new class of additives in the membranes. To date, several types of inorganic nanomaterials have been embedded in polymer membranes, such as zeolites [61], metal-organic frameworks (MOFs) [62], carbon nanotubes (CNTs) [63], porous organic cages (POCs) [64], silicas (mesoporous MCM-41) [65], graphene oxide (GO) [66], MOF-silica hybrid particles [67], titanium dioxide (TiO 2 ) [68], magnesium oxide [69] and Ag-based particles [70]. All these materials possess specific intrinsic features that enable them to provide enhanced properties to composite membranes.…”