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Table of contents entryHighly porous magnetic nanocomposite hydrogel (m-CVP) beads were prepared and used for the removal of dyes and heavy metal ions. AbstractNovel magnetic nanocomposite hydrogel (m-CVP) beads were prepared by instantaneous gelation of carboxymethyl starch-g-polyvinyl imidazole (CMS-g-PVI), poly(vinyl alcohol) (PVA), and Fe 3 O 4 mixture in boric acid solution followed crosslinking by glutaraldehyde (GA). Highly porous m-CVP beads with magnetic sensitivity were fully characterized and used as eco-friendly absorbent for removal of crystal violet (CV) and congo red (CR) dye and Pb(II), Cu(II) and Cd(II) from water. Batch adsorption results showed that the sorbent had high affinity to the heavy metals and dyes in water. The adsorption kinetics results showed that the adsorption rates could be described by pseudosecond-order kinetics indicating chemical sorption at rate determining step. Sorption of Pb(II), Cu(II), Cd(II), CR and CV to m-CVP beads agreed well to the Langmuir adsorption model at different ionic strengths with the maximum adsorption capacity of 65.00, 83.60, 53.20, 83.66 and 91.58 mg g -1 , respectively. Positive values of ∆H 0 showed that the adsorption was chemisorption, and the negative values of ∆G 0 indicated the spontaneity of the pollutant adsorption. Desorption and reusability of m-CVP beads was also investigated for tested heavy metal ions and dyes based on sequential adsorptiondesorption cycles. All the studied results indicated that m-CVP beads were an efficient, low cost, and reusable adsorbent for removal of dye and heavy metal ions from aqueous solutions.

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A series of magnetic semi-interpenetrating polymer network (semi-IPN) hydrogels was prepared in one-stage strategy composed of linear poly(vinyl alcohol) (PVA) chains and magnetic γ-Fe 2 O 3 nanoparticles entrapped within the cross-linked poly(acrylamide-co-vinylimidazole) (poly(AAm-co-VI)) network. The influence of PVA, weight ratio of AAm:VI, γ-Fe 2 O 3 , and MBA on the swelling properties of the obtained nanocomposite hydrogels was evaluated. The prepared magnetic semi-IPN hydrogels were fully characterized and used as absorbent for removal of Pb(II) and Cd(II) from water. Factors that influence the metal ion adsorption such as solution pH, contact time, initial metal ion concentration, and temperature were studied in details. The experimental results were reliably described by Langmuir adsorption isotherms. The adsorption capacity of semi-IPN nanocomposite for Pb(II) and Cd(II) were175.80 and 149.76 mg g À1 , respectively. The kinetic experimental data indicated that the chemical sorption is the ratedetermining step. According to thermodynamic studies, Pb(II) and Cd(II) adsorption on the hydrogels was endothermic and also chemical in nature. The prepared magnetic PVA/poly(AAm-co-VI) semi-IPN hydrogels could be employed as efficient and low-cost adsorbents of heavy metal ions from water.