Rapid and efficient uptake of aqueous lead pollutant using starch-based superabsorbent hydrogel

The need for a viable and sustainable environment has triggered the increased preference for eco-friendly agro-based biosorbents to synthetic ones. In this study, a superabsorbent hydrogel (‘c-hydrogel’) synthesized from a renewable agro-based precursor via polyacrylonitrile (PAN) graft copolymerization and subsequent hydrolysis was utilized for aqueous lead [Pb(II)] uptake. The chemical structure (using Fourier transform infrared spectroscopy, FTIR equipment), surface morphology (using scanning electron microscopy, SEM equipment) and the physicochemical properties of the synthesized ‘c-hydrogel’ were investigated. Similarly, the effect of some process variables on the biosorbents’ adsorption capacity, as well as the process equilibrium and kinetics modelling, was also undertaken in the study. The isotherm data were best fitted to the Langmuir and Temkin model, with a maximum adsorption capacity of 264.37 mg/g and fast kinetics of 40 min at pH 5.0. Conversely, the kinetic data were well fitted to the pseudo-first-order model. The ‘c-hydrogel’ showed a high water absorbency of 550 g water/g ‘c-hydrogel’ and demonstrated effectiveness, as a renewable and eco-friendly biosorbent for the aqueous lead ion [Pb (II)] removal.