Design of Recyclable Adsorbent for Water Pollutants Based on Chitosan-Coated Carboxymethyl Cellulose-Calcium Alginate Wrapped Iron Oxide-Copper Oxide Composite Beads

In this study, an efficient nanocomposite based on calcium alginate-carboxymethyl cellulose/iron oxide-copper oxide (CA-CMC/Fe₂O₃-CuO) is developed in beads form and utilized as nanoadsorbent and nanocatalyst. Further, the beads were coated with chitosan, resulting in Cs@CA-CMC/Fe₂O₃-CuO beads. The prepared beads exhibited exceptional adsorption capabilities for selected heavy metal ions. Notably, the Cs@CA-CMC/Fe₂O₃-CuO beads displayed remarkable adsorption among the other beads toward the three selected metal ions. Ag(I) was highly adsorbed by Cs@CA-CMC/Fe₂O₃-CuO beads, and the adsorption capacity of beads was 4.91 mgg⁻¹, while 4.5 mgg⁻¹ and 3.0 mgg⁻¹ for Co(II) and Ni(II), respectively. Beads’ ability to adsorb Ag(I) varied depending on several factors. It was observed that the adsorption capacity of Ag(I) ions increased as the interaction time and metal concentration rose. However, increasing the beads dose led to a decrease in the Ag(I) ion adsorption. Further, the waste beads after Ag(I) adsorption were treated with reducing agent to form beads supported Ag nanoparticles (Ag/Cs@CA-CMC/Fe₂O₃-CuO) and used as effective catalyst for reducing 4-nitrophenol in the presence of NaBH₄ as a reducing agent. Ag/Cs@CA-CMC/Fe₂O₃-CuO achieved reduction up to 93% for 4-NP within 30 min. The designed nanocomposite beads displayed several desirable attributes, including eco-friendliness and robust catalytic performance, making them highly promising for useful reduction of 4-NP.