A Novel Fabrication Approach for Multifunctional Graphene-based Thin Film Nano-composite Membranes with Enhanced Desalination and Antibacterial Characteristics

Hanaa M Hegab,Dusan Losic,Christopher P Saint,Linda Zou,Thomas G Barclay,Andrew Michelmore,Ahmed Elmekawy,Milena Ginic-Markovic

doi:10.1038/s41598-017-07531-y

Abstract

A practical fabrication technique is presented to tackle the trade-off between the water flux and salt rejection of thin film composite (TFC) reverse osmosis (RO) membranes through controlled creation of a thinner active selective polyamide (PA) layer. The new thin film nano-composite (TFNC) RO membranes were synthesized with multifunctional poly tannic acid-functionalized graphene oxide nanosheets (pTA-f-GO) embedded in its PA thin active layer, which is produced through interfacial polymerization. The incorporation of pTA-f-GOL into the fabricated TFNC membranes resulted in a thinner PA layer with lower roughness and higher hydrophilicity compared to pristine membrane. These properties enhanced both the membrane water flux (improved by 40%) and salt rejection (increased by 8%) of the TFNC membrane. Furthermore, the incorporation of biocidal pTA-f-GO nanosheets into the PA active layer contributed to improving the antibacterial properties by 80%, compared to pristine membrane. The fabrication of the pTA-f-GO nanosheets embedded in the PA layer presented in this study is a very practical, scalable and generic process that can potentially be applied in different types of separation membranes resulting in less energy consumption, increased cost-efficiency and improved performance.

Highlights

That intensify the adherence of bacterial cells[10, 11]
Integration of higher concentrations of pTA-f-graphene oxide (GO) resulted in the creation of thicker and rougher pTA-f-GO-PA active layers compared to pTA-f-GOL (Fig. 1c and d)
The results indicate that the water flux of the pristine membrane was significantly (p < 0.05) lower than other membranes fabricated with pTA-f-GO nanosheets (Fig. 5, Tables S1 and S2) with improvements in permeation compared to the pristine of 41%, 34% and 32% for the pTA-f-GOL, pTA-f-GOM and pTA-f-GOH fabricated membranes respectively

Summary

Introduction

That intensify the adherence of bacterial cells[10, 11]. As such, RO membranes have been modified with biocidal agents, made with smoother surfaces to reduce the number of bacterial binding sites and produced with more hydrophilic chemistry to generate a hydrogen bonded hydration layer, helping to prevent bacterial attachment[12]. As part of the efforts to address the challenges to RO technologies, a new type of thin film nanocomposite (TFNC) membrane was fabricated by incorporating zeolite nanoparticles within the polyamide (PA) active layer during the interfacial polymerization (IP) reaction[13, 14] This resulted in the enhancement of the membrane properties in terms of the water flux and biocidal efficiency, without losing the desalination performance of the TFNC membrane. More innovative research is still required to achieve TFNC membranes with high performance across all of the aspects of membrane filtration[15] Graphene nanosheets are another promising nanomaterial for RO TFNC membrane fabrication due to their smooth nature, superior biocidal activity and very large surface area[16, 17], but their chemistry prevents dispersal in most solvents and interactions with other TFC components. The fabricated membranes were subjected to a range of analyses to confirm their structure and chemical composition followed by evaluation of their water flux, selectivity, chlorine resistance and biocidal performance compared with pristine membranes enabling us to better understand the role of pTA-f-GO in improving TFC membrane performance

Methods

Results

Conclusion