Preparation of ultrahigh‐water‐content nanofiber composite hydrogel for Cd²⁺ removal

Abstract

BACKGROUND The rising volumes of industrial wastewater discharge are causing an ecological crisis, which has become a challenge for humans. Herein, a novel ultrahigh‐water‐content nanofiber composite (NC) hydrogel was prepared as an efficient adsorbent for cadmium ion (Cd2+). This hydrogel has a porous and loose 3D cross‐linked structure and the polymer chains are interspersed with titanium dioxide (TiO2) nanofibers, which provide a supporting framework for the NC hydrogel. RESULTS The adsorption of Cd2+ on the NC hydrogel could rapidly achieve the equilibrium and the maximum adsorption capacity (qmax) of 76.92 mg g−1 at pH 7 and 293 K. The intraparticle diffusion was the rate‐controlling step in the adsorption process, however, the diffusion coefficient (D) was just 2.57 × 10−10 m2 s−1 at 298 K, much lower than that of activated carbon. After five adsorption–desorption cycles, the NC hydrogel still maintained a certain adsorption efficiency, obtaining a regenerability close to 95.8%. Simultaneously, results of X‐ray photoelectron spectroscopy analysis revealed that the adsorption was mainly caused by the ion exchange between Cd2+ and calcium ion (Ca2+), and partly due to the chemisorption of Cd2+ by hydroxyl groups. CONCLUSION These results suggest that the innovative NC hydrogel can be a potential adsorbent material for removing heavy metal ions from industrial effluent. © 2020 Society of Chemical Industry