Citric acid crosslinked carboxymethyl cellulose/graphene oxide bead for adsorption of tetracycline from an aqueous system

Tetracycline (TC) and its derivatives are emerging contaminants in water systems with potential to accumulate in living organisms and spread antibiotic resistance. A novel oxygen-rich CMC/GO bead was fabricated as a chemically and thermally stable functionalized adsorbent for effective TC removal. BET analysis revealed that low-porosity micropores dominated the CMC/GO bead. The adsorption of TC onto the CMC/GO bead was most effective at pH 4. The monolayer adsorption capacities obtained via nonlinear and linear Langmuir isotherms are 267.11 and 277.78 mg/g, respectively, for 200 mg/L TC at neutral pH using 5 mg bead. The Hill isotherm describes the adsorption best, suggesting that the adherence of TC onto the bead permits cooperative interactions. The adsorption process is endothermic, and the bead is reusable, with 83.9% desorption during the third cycle using 1.0 M NaOH.