Multiwalled Carbon Nanotube-Foam Composites for Fixed-Bed Continuous Flow Column Adsorption of Dyes

The most practical application for wastewater treatment is the removal of dyes from aqueous solutions through fixed-bed column adsorption studies, which are conducted using MWCNT-foam. In this study, Multiwalled carbon nanotube (MWCNT)-foam nanocomposites were fabricated using the low-temperature chemical fusion (LTCF) process. These foam-based composites were subsequently employed in fixed-bed continuous flow column adsorption studies to remove anionic Congo Red (CR) and cationic Methylene Blue (MB) dyes from aqueous solutions. A fixed-bed column, packed with MWCNT-foam (bed height: 0.6 and 1.1 cm), was used to adsorb MB and CR from dye solutions (50 mg L–1). The column exhibited adsorption capacities of 5.6 and 7.8 mg g–1 for MB and CR, respectively, at a flow rate of 2 mL min–1. To assess the impact of bed height, flow rate, and initial dye concentration on column adsorption performance, breakthrough curves were analyzed using multiple models. The Thomas model provided the predicted adsorption capacities for both dyes as 14.46 mg g–1 for MB and 15.49 mg g–1 for CR. The τ values for both dyes were calculated using Yoon–Nelson model as 151 min for MB and 203 min for CR. The Adams–Bohart model predicted the N0 values as 17.33 mg L–1 for MB and 22.96 mg L–1 for CR. Moreover, the adsorption capacity of the MWCNT-foam composite in the fixed-bed column remained relatively stable even after three regeneration cycles, demonstrating its potential for long-term use in dye removal applications.