Clean Water Recycling Through Adsorption via Nanocomposites of Ti₃C₂T_x MXene-AgMOF and Graphene-Oxide-Ag-MOF

The use of dyes in many chemical industries, such as in the production of plastics, paints, papers, textile, has been increasing in recent years. Issues with environmental pollution related to dyes still exist if these chemicals are allowed to flow into wastewater bodies, since they are non-biodegradable, toxic, mutagenic, and carcinogenic. In this work, nanocomposites of GO-AgMOF and MXene-AgMOF were fabricated for the first-time using silver-based metal-organic framework (AgMOF). AgMOF has been functionalized by its heterogeneous bondage with graphene-oxide (GO) and Ti₃C₂T<i>_x</i> MXene and investigated for the adsorption of cationic methylene blue (MB) and anionic orange G (OG) dyes. The nanocomposites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and energy dispersive spectroscopy, before and after the adsorption. Batch adsorption tests suggested pseudo first-order kinetics of adsorption, suggesting a physical mechanism of adsorption. The effects of initial dye concentration and of pH were also studied. Very high adsorption efficiencies were observed for MB, with GO-AgMOF, MXene-AgMOF, and AgMOF able to remove 99.9%, 99%, and 98% of this dye from water at an initial concentration of 200 mg/L and an adsorbent mass of 0.01 g. In case of OG, adsorption efficiency did not exceed 20%, suggesting the electrostatic nature of the driving force for adsorption. The results suggest that these nanocomposites can be promising adsorbents for cationic contaminants, since 399.9 mg/g adsorption capacity was observed for GO-AgMOF. Incorporation of MXene into AgMOF enabled enhanced functionality to AgMOF, such as improving the adsorption capacity toward anionic and cationic dyes, suggesting that MXene-AgMOF can be further investigated for environmental remediation applications.