Search

A bi-functional chelating sorbent is synthesised by introducing two different functionalities (amine and amidoxime groups) subsequently on the surface of an earlier synthesized cross-linked poly-acrylonitrile beads. The cross-linked base polymer beads are normally synthesised through suspension polymerisation using acrylonitrile and styrene as monomers and divinyl benzene as cross-linking agent. The bi-functionality is introduced by amination of base polymer in the first step by reacting with diethylenetriamine followed by amidoximation reaction with hydroxylamine hydrochloride in the second step. The incorporation of functional groups on beads are identified and confirmed with FTIR spectroscopy while the surface morphology, porosity and pores dimensions are evaluated by SEM and BET techniques. The saturation sorption capacity of synthesized beads for uranyl ion is tested and found ~ 45 mg g−1, which is significantly higher than the beads functionalized with sole amidoxime group. These bi-functional beads are quite efficient over a wide pH (1–10) range. The kinetics measurements indicate that the synthesized sorbents reach its saturation sorption capacity within 2 h at ~25 °C under neutral pH. In this study, the sorbed uranyl ions are eluted out with 1 M HCl efficiently. These beads exhibit excellent reusability up to three cycles without losing much of its capacity, suggesting better usability in real samples. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]