Engineering Heterostructured Thin-Film Nanocomposite Membrane with Functionalized Graphene Oxide Quantum Dots (GOQD) for Highly Efficient Reverse Osmosis

Abstract

In this study, custom-tailored graphene oxide quantum dots (GOQD) were synthesized as functional nanofillers to be embedded into the polyamide (PA) membrane for reverse osmosis (RO) via interfacial polymerization (IP). The heterostructured interface-functionalization of amine/sulfonic decoration on GOQD (N/S-d-GOQD) takes place via the tuning of the molecular design. The embedded N/S-d-GOQD inside the PA matrix contributes to facilitating water molecules quick transport due to the more accessible capturing sites with higher internal polarity, achieving a nearly 3-fold increase in water permeance when compared to the pristine thin-film composite (TFC) membrane. Covalent bonding between the terminal amine groups and the acyl chloride of trimesoyl chloride (TMC) enables the formation of an amplified selective layer, while the sulfonic part assists in maintaining a robust membrane surface negative charge, thus remarkably improving the membrane selectivity toward NaCl. As a result, the newly developed TFN membrane performed remarkably high water permeance up to 5.89 L m–2 h–1 bar–1 without the compromising of its favorable salt (NaCl) rejection ratio of 97.1%, revealing a comparably high separation property when comparing to the state-of-the-art RO membranes, and surpassing the permeability-selectivity trade-off limits. Furthermore, we systematically investigated the GOQDs with different surface decorations but similar configurations (including 3 different nanofillers of pristine GOQD, amine decorated GOQD (N-d-GOQD), and N/S-d-GOQD) to unveil the underlying mechanisms of the swing effects of internal geometry and polarity of the embedded nanofillers on contributing to the uptake, and/or release of aqueous molecules within TFN membranes, providing a fundamental perspective to investigate the impact of embedded nanofillers on the formation of an IP layer and the overall transporting behavior of the RO process.

ZnO Nanoneedle-Modified PEEK Fiber Felt for Improving Anti-fouling Performance of Oil/Water Separation

“…Their FTIR spectra were collected and are shown in Figure b. In comparison with the original PEEK felt (PEEK-f), all of sulfonated felts had two new absorption peaks located at 960–1010 and 1038 cm –1 , which could be ascribed to vibrations of SO. − The result proved that the pressed felts were successfully sulfonated.…”

Advances in Integrating Carbon Dots With Membranes and Their Applications

“…Simultaneous modification of CDs with amine and sulfonic acid groups can give NF membrane better performance. CDs with amine/sulfonic acid (N/S‐CDs) were synthesized via microwave‐assisted pyrolysis of citric acid and diethylenetriamine (DETA) and Shen et al [34] . integrated them into the polyamide layer of the NF membranes (N/S‐CDs@membranes) through IP (Figure 3).…”

In Situ Assembly of Polyamide/Fe(BTC) Nanocomposite Reverse Osmosis Membrane Assisted by Fe3+–Polyphenolic Complex for Desalination

“…14−18 Although some progress has been made in improving the membrane permeability, the poor compatibility between inorganic fillers and PA matrix usually leads to defects in the structure, which severely affect the separation performance of the PA nanocomposite membranes. 19,20 There is a big challenge between filler material design and dispersion control in the fabrication of high-quality PA RO membranes for desalination. Metal−organic frameworks (MOFs) are a type of porous crystalline coordination compounds composed of metal centers or clusters and functional organic linkers.…”