Removal of tetracycline by La(OH)₃ modified MIL-101(Cr) adsorbent with multiple adsorption sites

The impressive water stability demonstrated by MIL-101(Cr) highlights its considerable potential for the effective elimination of organic contaminants from wastewater. Nevertheless, the limited availability of adsorption sites within MOFs leads to an unsatisfactory capacity for tetracycline (TC) adsorption. In this case, the lanthanum modified MIL-101(Cr) porous adsorbents, termed as nLa-MIL-101(Cr), were successfully synthesized using a post-synthetic modification method. Through various characterization analyses, it was confirmed that lanthanum exists in the form of La(OH)₃ within the adsorbents, and all adsorbents also preserved the original structure as MIL-101(Cr). The results of static adsorption experiments demonstrated that, compared to the original material, the adsorption capacity of 1La-MIL-101(Cr) for TC increased by 3.5 times. Further experiments demonstrated that the adsorbent exhibits remarkable ion interference resistance and cycle stability. Finally, based on X-ray photoelectron spectroscopy, the adsorption mechanism was primarily attributed to the coordination between TC molecules and metals active site, while electrostatic interactions also played a significant role in the process. This study has developed a highly efficient adsorbent for the treatment of TC-contaminated wastewater, which reflects promising practical application prospects.