Highly effective pH-universal removal of tetracycline hydrochloride antibiotics by UiO-66-(COOH)2/GO metal–organic framework composites

Effective removal of tetracycline hydrochloride antibiotics (TC) from aqueous solution has received widespread attention in the field of wastewater treatment. In this work, a Zr(VI)-based metal organic framework UiO-66-(COOH)2/GO composite was prepared and then used for TC adsorption. The maximum adsorption capacity of UiO-66-(COOH)2/GO reached 164.91 ​mg/g, with approximately five-fold higher than that of UiO-66 (27.53 ​mg/g). The enhanced adsorption performance of UiO-66-(COOH)2/GO is predominantly attributed to increased adsorption active sites caused by the introduction of GO and carboxyl groups. Particularly, the UiO-66-(COOH)2/GO adsorbent is pH-universal, showing ultra-high acid-base adsorption stability in acidic, alkaline and neutral media (i.e pH 1–11). The precursor amplification experiment proved the scalable preparation of UiO-66-(COOH)2/GO. Besides, adsorption behaviors were explored, including adsorption kinetics, isotherms and thermodynamics, effect of pH and coexisting ions. The possible adsorption mechanism is proposed on account of π-π interaction, chemical coordination, and weak electrostatic interaction between UiO-(COOH)2/GO and TC.