Preparation of a superparamagnetic nanocomposite hydrogel for adsorptive performance in the wastewater treatment

Abstract

ABSTRACT Magnetic nanocomposite hydrogels based on carrageenan (kappa:iota = 1:1) and maghemite (γ‐Fe 2 O 3 ) are prepared. Scanning electron microscopyimages show that the γ‐Fe 2 O 3 is dispersed on the surface of the hydrogels and transmission electron microscopy images show that maghemite particles are in nanometric size. The hydrogels present superparamagnetic behavior and respond to the stimulus of a magnet. The samples crosslinked with KCl are classified as superabsorbent materials (swelling degree >700%) and they show a higher saturation magnetization value than those crosslinked with CaCl 2 . Vibrating sample magnetometry curves show that the hydrogels do not present a hysteresis cycle and the remanent magnetization in all the samples is near zero. The performance of the hydrogels is evaluated for adsorption of heavy metals from aqueous solutions. The samples are immersed in aqueous solutions containing Cd(II) and Pb(II) ions. After 150 min of immersion, the hydrogels remove about 40% and 30% of each heavy metal contaminant, respectively. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47705.