Amine functionalized sodium alginate hydrogel for efficient and rapid removal of methyl blue in water.

Herein, a potential hydrogel based on sodium alginate (SA) integrated with polyethyleneimine (PEI) was fabricated and employed for the elimination of methyl blue (MB) in aqueous media. The SA/PEI hydrogel demonstrated excellent removal performance for MB, i.e. ~99% of MB could be removed from water within ~30 min using 0.5 g/L SA/PEI hydrogel at 100 mg/L initial concentration. The SA/PEI hydrogel presented maximum adsorption capacity for MB as-high as 400.0 mg/g with the adsorption isotherm and kinetics abide with the Langmuir isotherm model and pseudo second-order kinetics, respectively. The adsorption process followed through chelation between the functionality of the hydrogel and MB as-confirmed by the X-ray photoelectron spectroscopy (XPS) analysis. After four consecutive adsorption/desorption cycles, the adsorption capacity of the SA/PEI hydrogel remained up to ~60% of its adsorption capacity in first cycle. Thus, being a cost-effective and eco-friendly material, the SA/PEI hydrogel can be a potential adsorbent in the decontamination of MB in wastewater.