Environmentally benign approach for the efficient sequestration of methylene blue and coomassie brilliant blue using graphene oxide emended gelatin/κ-carrageenan hydrogels

Herein, we report the synthesis and characterization of gelatin/kappa-carrageenan crosslinked polyacrylic acid hydrogel (GT-CAG-cl-polyAA) and graphene oxide incorporated hydrogel nanocomposite (GO(HNC)) through a free radical crosslinking pathway. Under optimized reaction conditions, GT-CAG-cl-polyAA displayed 486 % maximum swelling percentage. TEM image depicted wrinkled silk veil wave-type surface morphology of graphene oxide (GO), whereas, the SEM analysis indicated the porous nature of the GT-CAG-cl-polyAA and GO(HNC) capable of accumulating a large number of water/dye molecules. GT-CAG-cl-polyAA exhibited 96.11 % and 82.16 % dye removal potential for the adsorption of methylene blue (MB) and coomassie brilliant blue (CB), respectively under optimized conditions. GO(HNC) enhanced the % dye removal efficiency (98.39 % for MB and 94.50 % for CB). The maximum adsorption capacity of GO(HNC) for the removal of CB and MB was 312.7 mg/g and 94.9 mg/g, respectively. The adsorption of CB and MB exhibited best fitting with Flory-Huggins adsorption isotherms data. The negative values of Delta G degrees and positive values of Delta S degrees which were obtained from the adsorption isotherm plot suggested the thermodynamic feasibility of the adsorption. Also, the samples were reusable for up to five consecutive cycles without any degradation and hence suggested a considerable pathway for the separation of textile dyes.

Automated summary

In this study, gelatin/kappa-carrageenan crosslinked polyacrylic acid hydrogel and graphene oxide incorporated hydrogel nanocomposite were synthesized and characterized. The adsorption performance of these hydrogel materials was investigated, and they showed good adsorption capacity for dyes removal.