Phosphorylation of chitosan/HEMA interpenetrating polymer network prepared by γ-radiation for metal ions removal from aqueous solutions

•CS/pHEMA IPN was synthesized by radiation polymerization.•Phosphorylation of CS/pHEMA IPN (Phos-CS/pHEMA) was achieved and confirmed.•Removal of Ca(II), Cu(II) and Zn(II) from aqueous solution was achieved.•The adsorption increased by Phosphorylation and adsorption capacity was in the order Cu(II)>Zn(II)>Ca(II).•Phos-(CS/pHEMA) is effective for adsorption of metal ions from aqueous solution. Interpenetrating polymer network (IPN) hydrogels, based on chitosan (CS) and 2-hydroxyethyl methacrylate (HEMA), have been prepared by γ-radiation followed by chemical modification via phosphorylation reaction and used for adsorption of Ca(II), Cu(II) and Zn(II) ions from their aqueous solutions. The gel content (%) increases with increasing the HEMA concentration. The maximum swelling (%) observed at the ratio (70/30) (CS/HEMA). CS/pHEMA IPN showed a higher thermal stability than CS. The phosphorylated hydrogel, Phos-(CS/pHEMA), characterized by XRD, EDS, SEM, DSC and TGA techniques. FT-IR spectra before and after adsorption of metal ions have been studied. Factors affecting the maximum adsorption capacity were also investigated. The maximum adsorption capacity using 0.01g Phos-(CS/pHEMA) was 66.3, 57.6 and 48.7 (mg/g) for Cu(II), Zn(II) and Ca(II) ions, respectively. The adsorption isotherms were simulated by Langmuir and Freundlich models and the adsorption kinetics were simulated by the pseudo-first-order and pseudo-second-order kinetics. The adsorption follows Langmuir models and pseudo-second order. The IPN hydrogels showed effective adsorption of the three metal ions from aqueous solution.