Highly Porous Multiwalled Carbon Nanotube-Foam Composite for Batch Adsorption Performances of Dyes

Treatment of dye pollutants prior to their release into the environment remains a formidable challenge, persisting as a longstanding issue. This study focuses on the development of a multiwalled carbon nanotube-foam (MWCNT-foam) composite through low-temperature chemical fusion (LTFC), resulting in a composite with a remarkably high accessible surface area (>475 m² g^-1). The MWCNT-foam composite exhibits a three-dimensional porous structure and demonstrates a notable affinity for organic dye adsorption. The efficacy of this composite was evaluated against various cationic dyes such as Methylene blue (MB) and Crystal Violet (CV) as well as anionic dyes such as Congo red (CR) and Eriochrome black T (EB), and the composite showed removal rates exceeding 99%. Furthermore, the study delved into the impact of the initial dye concentration, adsorbent dosage, kinetics, and other factors on the performance of the MWCNT-foam composite. The adsorption process achieved equilibrium in 10 min and strongly correlated with the pseudo-second-order kinetic model and Langmuir isotherm. The maximum adsorption capacity of MWCNT-foam for MB, CV, CR, and EB was found to be 168.63, 147.49, 99.50, and 93.11 mg g^-1, respectively. In order to showcase the potential of this material for continuous adsorption, a specialized cartridge was designed and employed to treat dye solutions, demonstrating the feasibility of continuous mode adsorption.