Production of continuous carbon nanotube/geopolymer composite fibers by wet spinning for adsorption applications

Porous geopolymers are highly regarded for dye and heavy metal adsorption due to their porous structure, versatile raw material options, and excellent chemical and thermal stability. Additionally, fiber-based adsorbents offer superior adsorption performance, with enhanced flexibility, adaptability, and a high surface area. In this study, pure geopolymer and carbon nanotubes (CNTs)/geopolymer continuous composite microfibers, with a diameter of ~ 300 µm, were synthesized using a wet spinning method. Sodium alginate (SA) was utilized as a dispersant, and a solution of 5% CaCl2 in 75% ethanol served as the coagulation bath. The morphology, structure changes, specific surface area, mechanical properties and adsorption properties of these composite microfibers were thoroughly studied. The addition of CNTs enhanced both the mechanical strength and the adsorption performance of microfibers for methylene blue (MB). The tensile stress and Young’s modulus of the CNTs/geopolymer fibers reached 35.41 ± 1.09 MPa and 33.22 ± 0.99 MPa, respectively, with a CNTs content of 25 wt.%. In addition, the high MB removal rates (~ 84%) were achieved after 24 h when the initial concentration of MB was 10 mg/L. These findings suggest that the obtained CNTs/geopolymer continuous composite microfibers are promising materials for adsorption applications, particularly in flexible, braided, and complex-shaped adsorption materials.