Carrageenan-based Hydrogel Nanocomposites Prepared in Presence of Carbon Nanotubes and Their Adsorption of Brilliant Green

Novel hydrogel nanocomposites, based on κ-carrageenan polysaccharide, were prepared by graft copolymerization of acrylamide (AAM) and maleic anhydride (MAH) as comonomers in the presence of multiwall carbon nanotubes (MWCNT), using methylene bisacrylamide (MBA) and ammonium persulfate (APS),former as a crosslinking agent and the latter as an initiator. The hydrogel nanocomposites structure was characterized by FTIR spectroscopy, scanning electron microscopy (SEM) and XRD patterns, and their thermal stability was investigated by TGA thermal analysis. The hydrogel nanocomposites were evaluated using gel content measurements and swelling rate in distilled water and in saline solutions. The carbon nanotube content was examined in relation to its effect on the properties of nanocomposites. The results showed that with increasing carbon nanotube content, the rate of water absorbency and equilibrium swelling in distilled water decreased whereas the water absorbency in the saline solutions increased. Water retention capacity was also studied and the results indicated that the inclusion of carbon nanotube increased water retention under heating condition. Furthermore, the experimental conditions of adsorption kinetics and dynamics for the removal of cationic dye, Brilliant Green (BG), were studied in the range of 6-8 for pH, 10-60 min for time (t), and 10-300 mg/L for initial concentration (C0) of the dye. The optimum conditions obtained for adsorption of Brilliant Green dye were pH 7, t= 50 min and C0= 10 mg/L. Also, the results indicated that more than 98% of the maximum adsorption capacity toward Brilliant Green dye was achieved within the initial 10 min. The experimental tests showed that the hydrogels could be used as fast–responsive and high capacity sorbents in Brilliant Green removal processes from industrial waste water.