Improved Forward Osmosis Performance of Thin Film Composite Membranes with Graphene Quantum Dots Derived from Eucalyptus Tree Leaves

Abstract

The major challenges in forward osmosis (FO) are low water flux, high specific reverse solute flux (SRSF), and membrane fouling. The present work addresses these problems by the incorporation of graphene quantum dots (GQDs) in the polyamide (PA) layer of thin-film composite (TFC) membranes, as well as by using an innovative polyethersulfone nanofiber support for the TFC membrane. The GQDs were prepared from eucalyptus leaves using a facile hydrothermal method that requires only deionized water, without the need for any organic solvents or reducing agents. The nanofiber support of the TFC membranes was prepared using solution blow spinning (SBS). The polyamide layer with GQDs was deposited on top of the nanofiber support through interfacial polymerization. This is the first study that reports the fouling resistance of the SBS-nanofiber-supported TFC membranes. The effect of various GQD loadings on the TFC FO membrane performance, its long-term FO testing, cleaning efficiency, and organic fouling resistance were analyzed. It was noted that the FO separation performance of the TFC membranes was improved with the incorporation of 0.05 wt.% GQDs. This study confirmed that the newly developed thin-film nanocomposite membranes demonstrated increased water flux and salt rejection, reduced SRSF, and good antifouling performance in the FO process.

Graphene Quantum Dot-Added Thin-Film Composite Membrane with Advanced Nanofibrous Support for Forward Osmosis

“…Thus, 2.0 wt.% of MPD was identified as the optimized monomer loading and was used for the preparation of the TFNC membranes and for further FO performance evaluation. The proper explanation for the higher flux values in the FO membranes with SBS nanofiber support was explained in a study by Saleem et al [ 30 ]. Here, the membrane’s nanoporous structure was an extremely significant factor that regulated its water flux and the rejection of solutes.…”

“…GQDs were synthesized from banyan tree leaves by adopting the preparation method reported by Saleem et al [ 30 ]. The powder of banyan tree leaves (5.0 g) was acquired via the ball-milling of leaves, and this powder was heated in DI water (200 mL) for 1 h at 80 °C temperature.…”

“…A diagrammatic representation of the synthesis stages of B-GQD is shown in Figure 1 . The GQD yield we obtained for the preparation from Eucalyptus tree leaves was 38.4% [ 30 ], whereas the GQD yield we obtained for the preparation from banyan tree leaves was 49.2%. Thus, it can be confirmed that banyan tree leaves is a better precursor than Eucalyptus tree leaves and neem leaves (25.2% yield) [ 67 ].…”

“…In recent times, nanomaterials have been successfully applied in various sectors for environmental remediation [ 28 , 29 ]. Numerous modification methods, such as nanomaterial inclusion into a selective layer or membrane substrate and membrane surface coating, have been examined to enhance the PA TFC membrane performance for specific applications [ 30 , 31 , 32 , 33 ]. Nanomaterials can be included into a selective PA layer by adding them into monomer solutions to develop thin-film nanocomposite (TFNC) membranes [ 34 , 35 ].…”

Sustainable Preparation of Graphene Quantum Dots for Metal Ion Sensing Application

“…GQD is a zero-dimensional (0-D) member in the carbon-based nanomaterials family and is generally considered a shredded fragment from a graphene sheet. This material has been studied widely since its unforeseen discovery in 2004, during the carbon nanotube’s purification, and it has a honeycomb structure with a single carbon layer [ 27 ]. It has exceptional electrical, structural, chemical, and tunable optical properties of PL as well as electrochemiluminescence.…”