Enhanced Adsorption of Malachite Green Using Carboxymethyl Cellulose/Carboxylic-Multiwall Carbon Nanotube Hybrid Hydrogel Nanocomposite

Synthesis and investigation of a sodium carboxymethyl cellulose grafting poly (acrylic acid) hydrogel (NaCMC-g-pAAc) and a sodium carboxymethyl cellulose grafting poly (acrylic acid)/carboxylic multiwalled carbon nanotubes hydrogel nanocomposite (NaCMC-g-pAAc\COOH-MWCNTs nanocomposite hydrogel) as malachite green (MG) dye adsorbents was undertaken in this study. The grafting reaction integrated a certain weight of oxidized COOH-MWCNTs into the hydrogel matrix through the copolymerization of acrylic acid AAC onto sodium carboxymethyl cellulose ( NaCMC). The resulting optimal hydrogel, with its maximum swelling capacity, was further combined with oxidized MWCNTs to form NaCMC-g-pAAc\COOH-MWCNTs, displaying a swelling capacity peak of 1800% at pH 7.0. The NaCMC-g-pAAc and NaCMC-g-pAAc\COOH-MWCNTs’ structure, thermal stability, and morphology were characterized utilizing techniques such as fourier transform infrared (FTIR), x-ray diffraction (XRD), TGA, and scanning electron microscopy (FE-SEM). Batch-wise investigations of the effects of pH, equilibrium time, weight, and salt on MG dye adsorption were conducted. Adsorbent’s negatively charged groups (COOH) were generated at an optimal pH 7, which established a strong interaction with MG’s positive charges, reaching adsorption equilibrium in 120 min. The adsorption potential of the NaCMC-g-PAA/COOH-MWCNTs hydrogel nanocomposite for MG was remarkably high, recorded at 198.8173 mg/g at 25°C. A suitable match for the dye adsorption data was found to be provided by both the pseudo-second-order model and the Freundlich model.