A study on the performance of a novel adsorbent UiO-66 modified by a nickel on removing tetracycline in wastewater.

In the present study, Ni-UiO-66 was synthesized to improve the adsorption efficiency of tetracycline (TC) in wastewater treatment. To this end, nickel doping was performed in the preparation process of UiO-66. The synthesized Ni-UiO-66 was characterized by XRD, SEM and EDS, BET, FTIR, TGA, and XPS for obtaining the lattice structure, surface topography, specific surface area, surface functional groups, and thermostability. More specifically, Ni-UiO-66 has a removal efficiency and adsorption capacity of up to 90% and 120 mg g, respectively, when used to treat TC. The presence of ions HCO, SO, NO and PO slightly affects the TC adsorption. A 20 mg L humic acid reduces the removal efficiency from 80% to 60%. The performed analyses revealed that Ni-UiO-66 had similar adsorption capacity in wastewater with different ion strengths. The variation of adsorption capacity with the adsorption time was fitted using a pseudo-second-order kinetic equation. Meanwhile, it is found that the adsorption reaction occurs only on the monolayer of the UiO-66 surface so the adsorption process can be simulated using the Langmuir isotherm model. The thermodynamic analysis indicates that the adsorption of TC is an endothermic reaction. Electrostatic attraction, hydrogen-bond interaction, and π-π interaction might be the main reasons for the adsorption. The synthesized Ni-UiO-66 has well adsorption capacity and stable structure. Accordingly, it is expected to achieve a good prospect in industrial applications and wastewater treatment plants.