Construction Of MXene-based Nanocomposites And Study On The Removal Of Antimony From Wastewate

Antimony（Sb）is a toxic heavy metal that is widely present in the environment and is highly mobile and exists in many forms,posing a great risk to the environment and human health.In recent years,iron（hydro）oxides（Fe OOH）have been widely used for the adsorption and removal of Sb from the aqueous environment due to their non-toxicity,abundance,and number of active sites.However,these Fe OOH materials are usually small in size and have a loose amorphous flocculation state in the aqueous phase,making their adsorption capacity unsatisfactory.In addition,the limited structural and chemical tunability of Fe OOH hinders their practical application.MXenes are a new class of two-dimensional metal carbide and nitride nanomaterials due to their unique physicochemical properties such as hydrophilic,two-dimensional layered morphology with high specific surface area,abundant functional groups,and tunable layer spacing.In this paper,alkali-treated MXene is first used as a nanocarrier to grow Fe OOH in situ on MXene,thereby synthesizing nanocomposites with tunable chemical structures and abundant active sites.The alkali-treated Ti₃C₂ MXenes also facilitate the capture of Sb species due to their abundant hydroxyl functional groups.However,the recycling and reuse of nanomaterials is still an urgent issue to be addressed.To this end,this paper subsequently uses cellulose nanofibres（CNFs）as functional scaffolds assembled with MXene,followed by in situ growth of Fe OOH nanorods to prepare layered nanocomposite films.The removal performance and removal mechanism of antimony from these nanocomposites and nanocomposite films are explored,respectively.the detailed research contents are presented as follows:（1）The effective removal of Sb（III）and Sb（V）from water is achieved by in situ growth of Fe OOH on alkalinized Ti₃C₂.After alkalinization,the negatively charged MXenes on the surface form stable heterojunctions between Ti₃C₂ and Fe OOH via electrostatic self-assembly,resulting in the uniform distribution of Fe OOH nanoparticles on the Ti₃C₂ nanosheets.The maximum adsorption capacities of the as-prepared Ti₃C₂@Fe OOH nanocomposites are 111.50 and 93.22 mg/g for Sb（III）and Sb（V）,respectively,outperforming most metal-based adsorbents.Density functional theory calculations show that the binding energy of Ti₃C₂@Fe OOH to Sb（III）is higher than that of Sb（V）,which is in agreement with the experimental results.X-ray photoelectron spectroscopy analysis shows that internal surface complexation and electrostatic attraction are the main forces for the removal of Sb.In addition,the as-prepared nanocomposites are reusable and sustainable in the treatment of Sb-contaminated wastewater.In electrochemical experiments,Ti₃C₂@Fe OOH after Sb adsorption can be used as a potential electrode material,thus minimizing the secondary pollution of the environment from the spent adsorbent.Overall,this section opens up new avenues for the remediation of heavy metal pollution in the aqueous environment by nano multi-layer composites.（2）To improve the practicality of the MXene-based composites,CNFs are used as functional scaffolds,assembleing with Ti₃C₂T_x MXenes,and forming interlocking topologies,which significantly improves the mechanical strength and toughness of the composite films.Meanwhile,β-Fe OOH nanorods grown in situ in the nano-gaps act as adsorption and photocatalysts to enhance the removal of the target pollutants.The as-prepared MXene@CNF@Fe OOH（MCF）nanocomposite membranes exhibit stable static removal of Sb.Excellent dynamic retention performance of Sb contaminated synthetic wastewater is achieved in continuous flow mode with high feed flow rates of 102.3 L/m²/h/bar,allowing rapid purification of antimony containing wastewater and meeting the permitted discharge standards.In addition,the MCF membranes exhibit an unique self-cleaning capability,degrading over 90%of the adsorbed organic dyes within 1 hour.Molecular dynamics simulations further demonstrate the excellent dynamic removal performance of the nanocomposite membranes for Sb.This section identifies the basis for the design of mechanically robust MXene based water purification membranes with good self-cleaning properties.Overall,the nanocomposites（membranes）designed in this work provides theoretical and experimental basis for exploring new generation of MXene-based water purification materials for efficient,rapid and sustainable treatment of heavy metal（antimony）contaminated wastewater.