Exploring the synergistic effect of MXene@ZIF-8 hybrid composites for water treatment

Due to their exceptional physical and chemical properties, MXenes have been the focus of growing research attention for their potential to effectively eliminate a wide range of pollutants from the aquatic environment. However, disadvantages such as limited adsorption capacity due to low specific surface area and undeveloped porosity have led to challenges in using these materials. In this work, we use a well-known MXene, Ti3C2Tx, by decorating zeolitic imidazole frameworks (ZIF-8) between MXene layers (MX@ZIF) to remove methyl orange (MO) and ciprofloxacin (CIP), as well as, the effect of -O and -OH terminal groups on adsorption efficiency of MX@ZIF substrate is investigated. Our findings from molecular dynamics simulations showed that the MXO@ZIF and MXOH@ZIF systems have stronger electrostatic interactions than the MX@ZIF system due to the formation of hydrogen bonds between the -O, -OH terminal groups from the substrates and heteroatoms of pollutant molecules. Moreover, the van der Waals energy values in the MXOH@ZIF-CIP and MXOH@ZIF-MO systems are - 253.454 and - 201.660 kJ/mol, respectively, demonstrating the effective adsorption and removal of contaminants by designed substrates. The MD results show that the van der Waals interaction has a greater contribution than the electrostatic interaction in studied systems. Also, the number of contacts of pollutant molecules with the substrate increases with time, and the highest number of contacts belongs to the MXOH@ZIF-CIP and MXOH@ZIF-MO complexes, demonstrating that this substrate has a greater tendency to adsorb pollutants. Furthermore, the results of AIM calculations confirm the presence of non-covalent interactions between pollutant molecules and studied substrates. This study shows that MXOH/ZIF can be considered a promising high-performance adsorbent for removing organic dyes and antibiotics.