New efficient and recyclable magnetic nanohybrid adsorbent for the metronidazole removal from simulated wastewater

Carbohydrate polymers, such as cellulose and its derivatives, are the most abundant materials that find in nature that can use as adsorbents for water treatment. Carboxymethyl cellulose (CMC) or cellulose gum is one of the cellulose derivatives with carboxymethyl groups which has features such as biodegradability, biocompatibility, hydrophilicity, non-toxicity, and low cost. In this case, CMC was utilized to synthesize CoFe2O4@CMC/Hydrogen-exchanged Zeolite Socony Mobil-5 (HZSM-5). The aim of this research was the synthesis of CoFe2O4@CMC/HZSM-5 in green conditions as a new nanomagnetic adsorbent for metronidazole (MNZ) removal from the aqueous media. The physicochemical structure of the adsorbent was characterized by various techniques. After that, in the adsorption process under the optimal conditions including pH 6, temperature 20 °C, MNZ concentration of 50 mg/L, contact time 60 min, and adsorbent dose 2 g/L, the synthetic and real samples removal efficiency was obtained 94% and 85%, respectively. The adsorption experiments were fitted with the Freundlich isotherm and pseudo-second-order kinetic. The values of entropy changes (ΔS = 46 J/mol k), enthalpy changes (ΔH = 9.33 kJ/mol), and negative Gibbs free energy changes (ΔG) showed that the adsorption process was endothermic, random, and spontaneous and had a physical mechanism. In addition, the findings showed that after the nanosorbent recovery, the adsorbent chemical structure did not change and the efficiency decreased to 86% after six runs. CoFe2O4@CMC/HZSM-5 magnetic nanocomposite had effective adsorption capacity for MNZ removal.