Resource recovery from textile wastewater: Dye, salt, and water regeneration using solar-driven interfacial evaporation

The solar-driven interfacial evaporation has created a new pathway in energy desalination. However, its application in the treatment of organic wastewater with high-salinity, such as textile wastewater, has not been studied. In this study, we have employed the activated carbon fiber cloth (ACFC) to treat textile wastewater. The ACFC exhibited excellent light-to-thermal conversion capacity, and the evaporation rate reached >1.188 kg m−2 h−1 for textile wastewater under 1 sun irradiation. Furthermore, salt and organic dye with high purity are well-separated by the evaporator, enabling ease of recovery. Up to 89.6% of salt can be recovered. The highest recovery rate of 69.2% was observed for Alizarin yellow R, which is an anionic dye and is repelled from the negatively charged ACFC surface. In addition, by modifying ACFC with cationic surfactant, the recovery rate for cationic dye increased significantly from 46.5% to 54.7% for rhodamine B. However, we found organic dyes can be partially degraded on the ACFC surface under solar irradiation due to carbon-mediated self-photosensitization, although its effect on the purity of recovered salt and organic dye is negligible. Overall, our study may open up new exploration of zero-liquid discharge technologies for the treatment of textile wastewater.