Surface Complexation Enhanced Adsorption of Tetracycline by ALK-MXene

The removal of tetracycline antibiotics from wastewater iscurrently an important environmental issue due to the serious waterenvironment pollution caused by tetracycline. However, the complexcomposition of industrial wastewater, including a wide variety of metal ions,may affect the removal efficiency of tetracycline. In this paper, ALK-MXenewith a hydroxyl-rich surface was prepared using an alkaline intercalation methodto remove tetracycline from wastewater. The effects of the presence of metalions, including Co(II), Cu(II), Cr(III), Cd(II), and Ni(II), on the adsorptionof tetracycline by ALK-MXene were explored. Batch adsorption experimentsshowed that the presence of metal ions could improve the tetracyclineadsorption capacity and that the removal capacity could be increased by 750%when coexisting with Ni(II). Three adsorption isotherm models, including theLangmuir model, Freundlich model, and monolayer model, were used toinvestigate the adsorption mechanism, and the results indicated that theadsorption follows the Freundlich model. Finally, systematic characterizations confirmed that adsorption occurred at the hydroxylsite on the surface of ALK-MXene, and the enhancement of surface complexation due to the surface modification of metal ions wasthe main mechanism for the increase in tetracycline adsorption