Preparation Of Ti₃AlC₂ MAX Phase-derived Nanomaterials And Investigation Into Their Performances In Heavy Metal Cd（Ⅱ） And Cu（Ⅱ） Adsorption

On the planet on which living things depend,the growth of animals and plants requires clean water.People are aware of the importance of environmental protection and health,and put forward higher requirements for the water quality of rivers,lakes and domestic water.Sewage treatment technology can significantly improve water quality.Among many water treatment methods,adsorption can be used to remove oxygen-consuming organic compounds,phenolic organic compounds,phosphorus and nitrogen-containing organic compounds,and heavy metal ions（such as lead,chromium,mercury,cadmium and copper,etc.）,and radioactive elements.In the development of new adsorbents,high adsorption performance has become one of the key and core issues.Transition metal carbides have specific active groups that can interact with metal ions,so they can be used for removal of heavy metal ions and radionuclides.We obtained titanium carbide material by hydrothermal treatment of MAX phase Ti₃AlC₂ under alkaline conditions.The chemical composition can be expressed as Ti₃Al_xC₂T_y（0≤x<1,T=OH or ONa）.The removal of element Al depends on hydrothermal synthesis conditions,such as the concentration and amount of alkali solution,reaction temperature and time,etc.By optimizing the synthesis conditions,we have obtained a pure fiber structure without aluminum,and the chemical composition can be expressed as Ti₃C₂T_x（T=OH or ONa）.On this basis,we added in situ glucose,cellulose,wood chips and other carbonaceous materials or manganese acetate metal salt precursors.By changing the raw materials and synthesis conditions（such as alkali solution concentration,reaction temperature and time）,the material morphology,composition and structure can be controlled.In particular,the surface is rich in oxygen-containing groups,so that the adsorbent has high adsorption heavy metal ions performance.The results of these studies can provide basic data and empirical reference for the removal of divalent heavy metal ions in environmental water by alkalized Ti₃AlC₂ derived materials.Hydrochar is one of the promising candidates derived by hydrothermal carbonization of biomass in pressurized hot water.The synthesis of“hydrochar-wrapped Ti₃AlC₂-derived nanofibers”was successfully achieved by a facile one-pot hydrothermal reaction using glucose as the hydrochar precursor.Meanwhile,cellulose and Chinese fir wood sawdust as raw materials were also investigated.Products were characterized by XRD,N₂ adsorption/desorption isotherms,Zeta potential,SEM,TEM and FT-IR to investigate their crystal structures,textural properties,morphologies,and surface species.In the adsorption test to remove Cd（Ⅱ）and Cu（Ⅱ）in aqueous solution,hydrochar-wrapped nanofibers outperformed pure nanofibers derived from Ti₃AlC₂,hydrothermal carbon derived from glucose and commercial activated carbon.Finally,the adsorbent regeneration,sorption kinetics,isothermal adsorption and adsorption mechanism were also explored.Using manganese acetate as an additive and glucose as a growth director and stabilizer,the same hydrothermal synthesis method was used to prepare"manganese-doped Ti₃AlC₂-derived nanofibers and nanosheets."The obtained solid samples were characterized using XRD,SEM,FT-IR,N₂ adsorption/desorption,XPS,Zeta potential,etc.The influence of the amount of manganese acetate added on the composition and morphology of the material was studied,and a preliminary law was obtained on the change of the morphology of the material.In the adsorption experiment,using the Cd（Ⅱ）aqueous solution as a model,the system studied the adsorption capacity,adsorption kinetics,isothermal adsorption performance of the composite materials.