Porous <scp>CNTs</scp>/<scp>SA</scp> Composite Aerogel for Sustainable Purification of Cationic Dyes From Wastewater

ABSTRACT The discharge of untreated dye wastewater into aquatic environments not only obstructs the photosynthesis of aquatic plants but also poses carcinogenic and mutagenic risks to organisms, threatening ecological balance and human health. Carbon nanotubes (CNTs) have been extensively employed for the removal of organic dyes from wastewater due to their high porosity, large surface area, and strong affinity for pollutants. However, their small size and low surface polarity render them susceptible to van der Waals forces, leading to poor dispersion in water and challenges in recovery, which may result in secondary pollution. In this study, we synthesized CNTs/sodium alginate (SA) aerogels characterized by a three‐dimensional porous network structure, employing sol–gel and freeze‐drying methods. These aerogels demonstrate remarkable adsorption capabilities for cationic dyes, achieving an adsorption capacity for methylene blue (MB) of 195.29 mg·g −1 , surpassing that of other adsorbents. Furthermore, the aerogels maintained a removal rate exceeding 80% after five cycles of adsorption and regeneration. These findings highlight the significant potential of CNTs/SA aerogels for the efficient purification of dye wastewater.