Novel thin film composite hollow fiber membranes incorporated with carbon quantum dots for osmotic power generation

By means of carbon quantum dots incorporation, we have developed novel thin film composite (TFC) membranes for osmotic power generation. The newly developed TFC membrane exhibits a peak power density as high as 34.20 W/m(2) at 23 bar using 1.0 M NaCl and deionized water as the feed pair. To our best knowledge, this is the highest ever power density reported in the literature. The carbon quantum dots (CQDs) are a new class of carbon nanomaterials with advantages of excellent hydrophilicity, low toxicity, environmental friendliness, easy synthesis and low cost. The CQDs are incorporated into the polyamide selective layers via the conventional interfacial polymerization reaction. The effects of incorporating different CQDs and their loadings on membrane morphology, properties and PRO performance have been examined. It is found that the addition of Na+-functionalized CQDs not only increases the existence of hydrophilic oxygen-containing groups and surface area of the polyamide layer, but also changes the morphology with a looser and thinner polyamide network. The TFC membrane comprising 1 wt% Na-CQD-9 has the optimal performance. Compared with the control, the water flux and power density at 23 bar increase from 44.52 to 53.54 LMH and 28.44 to 34.20 W/m(2) respectively, while the reverse salt flux remains unchanged.