Fabrication of cross-linked chitosan beads grafted by polyethylenimine for efficient adsorption of diclofenac sodium from water.

Diclofenac sodium (DS) is an emerging contaminant that is toxic and remains at high concentrations in natural aquatic environments. The aim of this study was to fabricate a novel spherical polymeric adsorbent composed of cross-linked chitosan beads grafted by polyethylenimine (PEI) to remove DS from water. The adsorbents were thoroughly characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, elemental analyses, and X-ray photoelectron spectroscopy. A cross-linking step was expected to enhance adsorption. The experimental data obtained from a series of adsorption experiments were fit well by the Langmuir isotherm model and pseudo-second-order model. The epichlorohydrin-PEI adsorbent (EPCS@PEI) showed a maximum adsorption capacity of 253.32 mg/g and removal efficiency of nearly 100% for the DS in the initial 50 mg/L solution. Therefore, EPCS@PEI is proposed as a potential adsorbent for DS removal, where these initial findings are expected to promote further design and fabrication of effective adsorbents for practical applications.