Co-Cu oxide nano-flake adsorbent for tetracycline removal from aqueous solution

In this study, a new adsorbent based on Co-Cu oxide nano-flakes was investigated to remove tetracycline from aqueous systems. Ultrasonic-assisted co-precipitation method has been used to synthesize the adsorbent nanoparticles with different precursor concentration of Cu²⁺/Co²⁺. The properties of the adsorbents have been investigated using BET, FESEM/EDS, XRD, and FTIR techniques. The removal experiment results show that the maximum tetracycline adsorption (q_max=195mg·gr^-1) was obtained for the adsorbent synthesized by Cu²⁺:Co²⁺ molar ratio of 1:5. The adsorbent nanoparticles have a Co₃O₄ spinel crystal structure and a flake-shape morphology with thickness of 20 nm. Incorporation of copper atoms in the spinel structure was confirmed by XRD and FTIR results and hence, effectively promotes the removal of the tetracycline. The effect of various parameters such as adsorbent weight, pH, and time on the kinetics of adsorption was investigated. The results showed that the Langmuir isotherm was in better agreement with the experimental data of tetracycline adsorption. The overall rate of adsorption follows the first-order kinetic model, although the results of intraparticle diffusion model showed that diffusion mechanism is one of the controlling steps during the adsorption process.