Metal-organic framework electrospun nanofibers in application to dye removal from textile wastewaters: A review

Emissions of dyes with wastewater from textile industries are increasing every year. Dyes, persisting or decomposing in the environment, enter drinking water through nature's water cycle and can cause severe problems to human health. Researchers have investigated and proposed various wastewater treatment techniques to reduce dyes' emissions, including adsorption, which appears to be the most cost- and time-effective. Metal-organic frameworks (MOFs) are adsorption materials used for many applications for their high specific surface area, pore size, and volume tunability. In dye removal, MOFs are used exceptionally in batch experiments, which hinders their application on an industrial scale. In this review, a comprehensive understanding of the most recent strategies for MOF synthesis is discussed with a focus on effective adsorption of dyes. The most considered interactions between MOFs and dyes are presented with examples and an endeavor is made to understand the contribution of surface charge and size compatibility to adsorption process. Furthermore, the present survey presents the strategies for incorporation of MOF into electrospun nanofiber (ENF) carriers in detail and demonstrates examples of MOF/ENF composite’s effective application towards the adsorption of dye in textile effluents. It is highlighted that dye-MOF interactions are mostly responsible for the dye adsorption process on MOF/ENF. Current limitations of MOF/ENF application in industrial textile wastewater treatment are extensively discussed and include technical and environmental concerns. These limitations need to be resolved before commercialization, and we suggest a number of studies that can be conducted to address this issue.