Incorporation of Silver-Embedded Carbon Nanotubes Coated with Tannic Acid into Polyamide Reverse Osmosis Membranes toward High Permeability, Antifouling, and Antibacterial Properties

Abstract

In this work, tannic acid (TA)-functionalized carbon nanotubes (CNT@TA) were synthesized by hydrogen bond and π−π stacking interactions. CNT@TA embedded with silver nanoparticles (Ag-CNT@TA) was obtained by in situ reducing silver ammonia ions in the pore channels of CNT@TA. CNT@TA and Ag-CNT@TA were added into the polyamide (PA) layer by interfacial polymerization to fabricate high-performance nanocomposite reverse osmosis membranes. The results show that the functionalized CNTs can be uniformly distributed in the PA matrix with random orientations. A loose PA separation layer was obtained by introducing CNT@TA. Correspondingly, abundant new water channels were formed. Compared with the pure PA membrane, the water permeability (4.81 L m −2 h −1 bar −1 ) of the nanocomposite membrane is enhanced by 49.8% without any loss in NaCl rejection (99.3%). The membrane exhibits satisfactory chemical-and bio-fouling resistances to bovine serum albumin and Escherichia coli as model foulants. The high bactericidal rate should be ascribed to the formation of the TA coating and confined Ag nanoparticles in CNT channels. The confined structure effectively avoids the leaching out of the Ag nanoparticles and keeps the persistence of the antibacterial property. The excellent compatibility between the CNTs and the polyamide matrix endows the membrane with long-term performance stability.

Antimicrobial activity of thin-film composite membranes functionalized with cellulose nanocrystals and silver nanoparticles via one-pot deposition and layer-by-layer assembly

“…The reason for this observation could be attributed to the nucleation of AgNP on CNC, which improves the stability of AgNP, thereby reducing the pace at which the metallic AgNP oxidizes and dissolves into the neighboring solution. The average Ag + leaching rate of TFC-OP, estimated as 0.027 μg cm −2 per day, is lower than that of deposited AgNP 68 and similar to the release rate observed in membranes modified with a hybrid nanomaterial consisting of tannic acid-functionalized carbon nanotubes embedded with in situ nucleated AgNP 69 (Table S3 †).…”

Tannic Acid-Based Coatings Containing Zwitterionic Copolymers for Improved Antifouling and Antibacterial Properties

“…The EDX results indicated that the control TA/Ag and TA/pMP coatings exhibited the highest percentages of the silver element compared with the surfaces covered with copolymers. This high silver content can be explained by many catechol groups on the TA layer that reduce silver ions into AgNPs . By contrast, the amino groups on copolymer coatings can bind covalently with TA, resulting in fewer catechol groups and fewer AgNPs on the surfaces.…”

“…This high silver content can be explained by many catechol groups on the TA layer that reduce silver ions into AgNPs. 44 By contrast, the amino groups on copolymer coatings can bind covalently with TA, resulting in fewer catechol groups and fewer AgNPs on the surfaces. As expected, the EDX results for the pMP8AE2/Ag coating, with the highest ratio of AEMA content, showed that this coating had the lowest percentage of AgNPs, which could be ascribed to the low number of catechol groups available to reduce silver ions.…”

Natural Nanoclay-Based Silver–Phosphomolybdic Acid Composite with a Dual Antimicrobial Effect

“… 4 , 5 Another promising approach is to use the biocide-release coatings that release bactericidal components that cause bacterial inactivation. 6 − 9 However, for most applications, the antibacterial coatings must withstand mechanical stress and combine antibacterial response and rigidity. 10 , 11 …”

“…The problem of microbial growth and biofilm formation on the different surfaces remains a significant concern, especially in the context of antibiotic misuse and the spreading of hospital infections . Nanomaterials can serve as the antibiotic-free remedy and prevent intraclinical bacterial transmission. , Nanostructured surfaces provide mechano-bactericidal action, which could be combined with superhydrophobicity, thus preventing surface contamination. , Another promising approach is to use the biocide-release coatings that release bactericidal components that cause bacterial inactivation. − However, for most applications, the antibacterial coatings must withstand mechanical stress and combine antibacterial response and rigidity. , …”