Carboxymethyl cellulose grafted poly(acrylamide)/magnetic biochar as a novel nanocomposite hydrogel for efficient elimination of methylene blue

In the present study, the grafting of acrylamide (AAm) onto the carboxymethyl cellulose (CMC) backbone was performed using the free radical polymerization method to eliminate methylene blue (MB) from water media. Biochar (BC) was produced from tea waste by pyrolysis and doped with Fe3O4 nanoparticles. Magnetic biochar (MTWBC) nanoparticles were incorporated in CMC-g-P(AAm) hydrogel (HG) for the first time to enhance its adsorption properties. FTIR, XRD, TGA, VSM, BET, and SEM-EDS techniques characterized synthesized nanoparticles and adsorbents. The BET surface area for HG, HG/BC, and HG/MTWBC was obtained at 1.74, 2.011, and 3.58 m2/g, respectively, demonstrating how BC and MTWBC nanoparticles can enhance the surface area of HG. The magnetic saturation of MTWBC and HG/MTWBC was 15.45 and 1.85 emu/g, respectively. The maximum removal performance of HG, HG/BC, and HG/MTWBC nanocomposite hydrogels under optimum conditions of pH = 8, adsorbent dose 1.5 g/L, contact time 70 min, initial concentration 10 mg/L, and temperature 25 degrees C was obtained 83.22, 92.57, and 94.27%, respectively showing the effectiveness of BC and MTWBC nanoparticles in promoting removal performance of HG. Kinetic and equilibrium data followed Langmuir and pseudo-second-order models, respectively. The monolayer adsorption capacity for HG, HG/BC, and HG/MTWBC nanocomposite hydrogels was computed to be 12.3, 14.2, and 20.79 mg/g, respectively. The thermodynamic study showed that the MB elimination process is spontaneous and exothermic. The adsorption mechanisms of MB onto HG/MTWBC include hydrogen bonding, electrostatic interaction, and pi-pi interactions. Finally, it can be inferred that HG/MTWBC nanocomposite hydrogel can be applied as a novel, easy-separable, and efficient adsorbent to decontaminate MB from water media.