Ultra-strong adsorption of organic dyes and antibiotic onto the alk-MXene/ZIF adsorbents with a specific intercalation structure

Abstract

By in-situ growing tiny ZIF (ZIF-67/ZIF-8) particles on the interlayer and surface of alkalized MXene (alk-MXene), alk-MXene/ZIF adsorbents with specific intercalation structure and ultra-strong adsorption capacity for antibiotics and dyes are designed. The introduction of ZIF particles offers a larger specific surface area and more adsorption functional groups in alk-MXene/ZIF composites. Changing the additive amount of alk-MXene (1, 0.5 and 0.25 g) can effectively tune the adsorption properties and morphology of the composites. Herein, when the additive amount of alk-MXene is 0.5 g (sample S2) exhibits optimal adsorption performance with maximum adsorption capacities q_m of 539.7, 1053.3 and 7111.3 mg g⁻¹ for Congo Red (CR), Tetracycline (TC) and Malachite Green (MG). That is, too much (sample S1) or too little (sample S3) addition of the alk-MXene into the composites will suffer the performance degradation. Impressively, the composites show fast adsorption kinetics, strong recycling ability and powerful anti-interference capacity to multiple ions in contaminants. Benefiting from the intercalation structure, ZIF particles protect alk-MXene from being oxidized in air, making the composites exhibit excellent chemical stability. Typically, Sample S2 retains its stable microstructure and outstanding adsorption properties in air for 45 days. Also, the actual application of sample S2 is analyzed by filtering the adsorbates multiple times. Furthermore, it is demonstrated that the synergistic effects of electrostatic interaction, hydrogen bonding and π-π stacking lead to the excellent adsorption capacity of alk-MXene/ZIF composites. This study suggests that alk-MXene/ZIF can be regarded as a high-efficiency and promising adsorbent to remove organic dyes and antibiotics.