Bionic Construction Of Wood-based Magnetic Materials And Their Functions

Recently,energy issues,climate changes,and environmental pollution have become increasingly serious problems,and achieving sustainable development has become a global consensus.Advanced functional materials made from green and renewable wood have received great interest in energy storage,water treatment,intelligent electronic devices,ion conduction,and other fields.As a natural organic polymer composite,wood has a three-dimensional porous hierarchical structure composed of lignin,cellulose,and hemicellulose.Using highly oriented microfibres in wood structure and tracheids used to conduct water,air and ions during metabolic processes,functional wood nanomaterials can be obtained by various mechanically and chemically treated,which have great potential used in high-tech fields.This paper uses the natural poplar and poplar powder from the Maoershan experimental forest farm as raw materials.Based on the magnetic properties of pigeon and sea turtle,we prepared the wood-based magnetic nanocomposites via the low-temperature hydrothermal treatment and vacuum impregnation processes.Multi-functionality can be obtained by further surface modification.The magnetic,hydrophobic and anti-ultraviolet properties of magnetic wood were studied.And the potential application of wood-based magnetic materials in the fields of magnetism,optics,induction heating,and adsorption waste was also evaluated.The main research contents of this paper are summarized as follows:(1)Based on low-temperature hydrothermal method,magnetic wood/CoFe2O4 nanocomposites with uniform distribution,complete crystal grains and stability can be prepared by low-temperature hydrothermal methods.The surface morphology of magnetic CoFe2O4 nanoparticles grown on the surface of the wood is greatly affected by the hydrothermal temperature.The high hydrothermal temperature is beneficial to the growth of magnetic nanoparticles with larger particle size on the surface of wood,resulting in higher magnetic saturation magnetization.In the initial stage of magnetic wood formation,prolonging the reaction time is beneficial to obtain magnetic wood with higher saturation magnetization,but when the reaction time exceeds 8 hours,the magnetic nanoparticles were grown on the surface of the wood reach saturation,so the magnetic properties of the magnetic wood will be relatively weakened.The reactant concentration ensures the growth of high purity spinel phase CoFe2O4 on the surface of the wood.(2)Based on low-temperature hydrothermal method,magnetic CoFe2O4 nanoparticles are deposited on the surface of the wood to form a rough binary structure on the surface of the wood.After further modification by low surface energy octadecyl trichlorosilane,a functionalized wood material with magnetic properties,superhydrophobic ity,and UV-aging resistance can be obtained.The room temperature hysteresis loop of the superhydrophobic magnetic wood exhibits a saturation magnetization of 1.71 emu g-1,and the water contact angle of magnetic wood up to 150°.After 1200 hours of UV aging,the UV-resistant of the magnetic wood was improved at least 3 times compared to untreated wood.(3)Based on vacuum impregnation method,preparing a stable sodium oleate modified Fe3O4 precursor solution,the Fe3O4 nanoparticles can be effectively deposited in the wood cell wall through vacuum impregnation and hydrothermal processes,thereby the magnetic Fe3O4/wood possesses excellent magnetic properties.By changing the amount of added Fe3O4 nanoparticles,it is possible to control the magnetic properties of Fe3O4/wood.The magnetic induction heating test proves that the magnetic Fe3O4/wood has an excellent magnetocaloric effect,and the surface temperature of the magnetic wood rises rapidly after 10 minutes of excitation in a low-frequency magnetic field of 35 kHz.With the increase of nano-Fe3O4 loading,the magnetocaloric effect is more obvious.When the magnetic nanoparticle loading is 25 wt%,the surface temperature of the magnetic wood can be raised to 70.1?.However,the high Fe3O4 loading tends to cause agglomeration of the magnetic nanoparticles,so the heating efficiency of the magnetic wood decreases as the Fe3O4 loading increases.When the magnetic nanoparticle loading is 9.4 wt%,the magnetic heat efficiency of the magnetic wood can reach the highest value.(4)Based on vacuum impregnation method,immersing magnetic fluorescent nanoparticles and polymethyl methacrylate,into delignified wood,fluorescent transparent magnetic wood with luminescent,transparent and excellent magnetic properties can be prepared.Among them,the nanoparticles and the transparent resin are completely immersed in the wood cells and firmly bonded to the wood cell wall,resulting in excellent light transmittance,fluorescence and magnetic properties of prepared fluorescent transparent magnetic wood.(5)Using natural waste-wood sawdust,magnetic sawdust was prepared by using poplar powder as raw material soaked in magnetic precursor solution thought a hydrothermal process,then further modified by amino functionalization to synthesize magnetic wood powder with the ability to adsorb heavy metal ions(Cu2+).Compared to the original wood sawdust,magnetic sawdust provides a larger specific surface area and a sufficient active site for adsorbing Cu2+.The adsorption isotherm fitting indicated that the Langmuir isotherm model is more suitable for describing the adsorption process of Cu2+by amino-functionalized magnetic sawdust,and its maximum adsorption capacity for Cu2+is 7.72 mg/g.More importantly,the amino-functionalized magnetic wood powder has excellent recovery performance and can be easily recycled under the action of a strip magnet.After 5 cycles,the adsorption efficiency of Cu2+ions still reaches 77.4%,indicating the good reusability.(6)Using natural waste-wood sawdust,magnetic wood sawdust with magnetic,superhydrophobic and lipophilic properties can be prepared through effectively combined with the magnetic CoFe2O4 nanoparticles,and further modified by surface energy silane.The prepared superhydrophobic magnetic sawdust has excellent magnetic properties,and its room-temperature saturation magnetization is 6.1 emu g-1.Meanwhile,the prepared magnetic sawdust has a contact angle with water of 151° and a contact angle with oil of 0°,demonstrating excellent hydrophobicity and lipophilicity.The super-hydrophobic magnetic sawdust exhibits the ability to quickly absorb oil on the surface of the water,and the capability of absorbing oil more than 11.5 times of its own weight.In addition,it has excellent adsorption capacity for methanol,ethanol,n-hexane,octane,diesel,and crude oil,and it can be widely used to adsorb various organic pollutants.More importantly,the strip magnet can be used to quickly recycle the adsorbent because of the good magnetic properties.The stability test results of the material show that the superhydrophobic magnetic wood powder has an anti-acid resistance and long-term storage capacity,demonstrating the potential in actual oil-water separation.