Novel green sustainable hydrogel composites based on guar gum and algal species for wastewater remediation

Abstract An innovative approach was developed for removing very potent heavy metal cations and dyes such as lead (Pb +2 ), copper (Cu +2 ) and methylene blue (MB) from simulated solutions at different application conditions. The sorbent material was green hydrogels based on guar gum/poly acrylamide (GG/PAam) fabricated with rice husk core (GG/PAAm/RH) and the optimized formulation was blended with Ulva fasciata and Sargassum dentifolium green algae (denoted as GG/PAAm/RH/Ulva and GG/PAAm/RH/Sarg respectively). The chemical modification process was confirmed by FTIR. The effect of rice husk on the crystallographic and the thermal properties of the hydrogel composites was verified via the XRD and TGA analyses respectively. The surface topography versus structure variation and adsorption process of the aforementioned hydrogels were substantiated by the AFM in order to prove their suitability as effective candidates for wastewater remediation. Different adsorption and kinetic isotherms were applied to precisely describe the adsorption process. The data reveal that the adsorption mechanism best fit multilayer adsorption Freundlich process with q max values onto GG/PAAm/RH/Ulva and GG/PAAm/RH/Sarg as follows: 50.25 and 73.52 mg g for adsorption of Cu +2 , 45.24 and 52.63 mg g for Pb +2 , and 51.54 and 68.02 mg g for MB. The reusability investigation proved that the algal-supported sorbents were very successful in removing of reasonable amounts of pollutants after four adsorption–desorption cycles. Graphical abstract