A new way to combine carboxymethyl cellulose with Fe: Application and mechanism analysis

A new, effective powdered adsorbent (CMCFe) for removing oxytetracycline (OTC) was synthesized successfully in an acidic environment using a thermal fusion technique. CMC-Fe underwent comprehensive SEM, EDS, FT-IR, XRD, XPS, TGA, and BET analyses before and after adsorbing OTC. These studies systematically examined preparation variables such as CMC and FeCl₃ ratios, acetic acid quantity, reaction duration, and temperature. Batch adsorption experiments evaluated how well CMC-Fe absorbs OTC, with detailed analyses of adsorption mechanisms through kinetics, isotherms, and thermodynamic methods. Characterization analysis of CMC-Fe pre- and post-OTC adsorption confirmed its stability, high adsorption capacity, and the presence of OTC on its surface. Within 2 h, batch adsorption experiments demonstrated that CMC-Fe could adsorb up to 1005 mg·g^-1 of OTC. Examination of kinetics, isotherms, and thermodynamics showed that OTC adsorption by CMC-Fe is a complex, multilayered, endothermic process where physical adsorption prominently contributes to OTC removal. Key factors driving the adsorption process include chelation involving Fe²⁺, Fe³⁺, and OTC, π-π stacking, pore filling, and strong electrostatic interactions. CMC-Fe exhibits exceptional adsorption capacity for OTC, demonstrating strong environmental adaptability and promising potential for pollutant removal in aquatic environments.