Microwave-assisted synthesis of gum gellan-cl-poly(acrylic-co- methacrylic acid) hydrogel for cationic dyes removal

The present work highlights the microwave-assisted synthesis of novel superabsorbent gum gellan cross-linked poly(acrylic-co- methacrylic acid) hydrogel [GG-cl-poly(AA-co-MAA)] prepared by the simultaneous graft copolymerization using ammonium persulfate as the initiator and N,N′-methylene-bis-acrylamide as the cross-linker for the removal of cationic dyes [malachite green (MG) and methylene blue (MB)]. The GG and hydrogel were studied by using Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction spectroscopic techniques. Swelling studies were conducted out in various concentrations of initiator, monomer, and cross-linker. The outstanding dye removal efficiency of ~ 99% for MG and ~ 95% for MB was found at the initial dye concentration of 50 mg L^-1 with an adsorbent dose of 500 mg within the time duration of 6 h and 25 °C. The adsorption kinetics data for both MG and MB dyes exhibited the pseudo-first-order kinetics.