Granular hydrogel initiated by Fenton reagent and their performance on Cu(II) and Ni(II) removal

With acrylic acid (AA) and allylthiourea (AT) as the monomers, an “instantaneous” granular hydrogel was prepared using Fenton reagent as redox initiator under an ambient temperature in air atmosphere, and then characterized by means of Fourier transform infrared spectroscopy and scanning electron microscope. The obtained hydrogels were investigated as the adsorbents to remove Cu(II) and Ni(II) from the aqueous solution. The effects of operating parameters on the adsorption capacity were studied, including the composition ratio (AT:AA), contact time, pH and initial concentrations of heavy metal ions. The results indicate that the introduction of allylthiourea into the hydrogel can reduce greatly the swelling ratio, but with no significant variation in the adsorption capacity as the initial Cu(II) and Ni(II) concentrations lower than 400 and 200 mg/L, respectively. In addition, the adsorption capacity shows a pH-independence at pH ⩾ 4.0, and the adsorbed Cu(II) and Ni(II) can be partially desorbed using 0.01 mol/L HCl as the desorbent, rendering the as-prepared hydrogel good re-adsorption ability, especially for Cu(II). The applicability in real electroplating wastewater demonstrates that the as-prepared hydrogel with AT is promising for the removal of Cu(II) and Ni(II) for its comparable adsorption capacity with the hydrogel without AT.

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► Granular hydrogel was formed using Fenton reagent in air atmosphere.
► Allylthiourea was used to decrease the swelling degree during the adsorption.
► The hydrogel can interact with Cu(II) and Ni(II) via different functional groups.
► The hydrogel can work as effective adsorbent for treatment of a real wastewater.