Radiation grafted polyacrylic acid–polyurethane foam copolymer for efficient toxic metal removal from aqueous waste: a sustainable approach to waste management

Abstract

The acrylic acid-grafted functionalized base polyurethane foam (PAA-g-PUf) is synthesized through mutual radiation grafting technique using acrylic acid as functional monomers and polyurethane form (PUf) with macroporous structure as base polymer, for the extraction of lead from the aqoueous waste streams. The incorporation of functionality on PUf is identified and confirmed by FT-IR spectroscopy, degree of grafting and thermal stability by TGA–DSC technique while the surface morphology, and pores dimensions are evaluated by SEM techniques. The kinetics measurements indicate that the synthesized sorbent reaches its saturation sorption capacity within 10 min at ~ 25 °C under near-neutral pH condition. The monolayer sorption capacity of the synthesized PAA-g-PUf for lead ion (Pb2+) is calculated from Langmuir’s model and found to be ~ 257 mg g−1, which is quite good as compared to the other functionalized material available. These grafted foams are quite efficient over a wide range of concentrations and temperature of the experimental solutions. In this study, the adsorbed lead ions are eluted out in 0.5 M HCl strippent efficiently. These sorbents exhibit excellent reusability up to five cycles without losing appreciable capacity, suggesting better usability in real water samples for many cycles. The polyurethane foam used was obtained from municipal waste, and hence, they cannot generate any additional secondary waste to the environment and make the process more sustainable and economically viable.Graphical abstract