Progress and Perspective for Carbon Quantum Dots and Analogous Carbon-Based Nanomaterials in Augmenting Forward Osmosis Performance

Forward osmosis (FO) has emerged as a new star in the family of membrane-based separation processes not only as a stand-alone system for high-fouling feed but also in combination with other membrane processes. In spite of being a non-pressurized process, their widespread commercial applications compared to classical technologies are still constrained by core challenges, primarily low flux, concentration polarization, energy-intensive draw, and solute recovery. Carbon Quantum dots (CQDs) - an emerging class of carbon-based smart nanomaterials has stimulated a renewed interest in FO research for membrane as well as draw solutes development. Given the general panorama of past-to-present literature, the paper intends to provide a comprehensive survey on the CQD synthesis and their various modes of incorporation into FO membranes for process improvement. Thin film nanocomposites and active skin layers modification by incorporation of CQDs, via phase inversion or interfacial polymerization, were attempted by researchers and compared to other techniques. Although CQD incorporation resulted in appreciable water flux improvements, the reverse solute flux remains a concern. The uses of CQDs, both as a pristine and functionalized version, prove to be promising as a valuable ingredient of draw solute for the FO process.

Automated summary

Forward osmosis (FO) is a membrane-based separation process that has attracted attention as both a stand-alone system and in combination with other membrane processes. However, its commercial applications are limited due to challenges such as low flux, concentration polarization, energy-intensive draw, and solute recovery. Carbon Quantum dots (CQDs) have shown promise in improving FO performance, but the issue of reverse solute flux remains a concern. The use of CQDs, both in pristine and functionalized forms, shows potential as valuable draw solutes for FO processes.