Absorption Thermodynamic and Kinetics of Heavy Metals by Magnetic Hydrogel Nanocomposite Absorbents with Semi‐interpenetrating Networks Structure

KH570-modified magnetic hydrogel nanocomposite absorbents (KH570-mHNAs) with semi-interpenetrating networks (semi-IPNs) were synthesized by radical copolymerization based on poly(acrylamide-co-acrylic acid), PVP and KH570-modified magnetic nanoparticles. KH570-mHNAs with porous and ravine structure have the target structure confirmed by FTIR and XRD results. KH570-mHNAs have high adsorption capacities of Cu(II) (163 mg/g), Cd(II) (150 mg/g), and Pb(II) (460.8 mg/g), approaching the absorption equilibrium at 60 min. Heavy metal absorption was highly dependent on different process variables, such as pH value, initial heavy metal ion concentration, contact time, and temperature. The endothermic, entropy increasing, and spontaneous nature of heavy metal ion adsorption was revealed from thermodynamic study. Heavy metal ions adsorption isotherms and kinetics were in agreement with the Langmuir model and pseudo-second-order kinetic model, respectively. Besides, KH570-mHNAs had good magnetic responsiveness, desorption, and reusability, which made it a promising adsorbent for removing heavy metal ions from the contaminated wastewater.