Research On The Preparation Of Nano-hydroxyapatite And Its Composite Materials Based On Ionic Liquid

With the rapid development of economy and technology,based on the need for environmental protection,pollution-free clean technology has received increasing attention from all over the world.The development of green chemistry has become the theme of the current era.The excellent properties of ionic liquids make it an extremely promising application in green chemistry such as non-volatility,low melting point,wide liquid range and stable properties.This research topic fully utilizes the advantages of ionic liquid greening,and makes ionic liquids also serve as a template for the synthesis of nano-hydroxyapatite,a solvent for cellulose in combination,and a dispersant for nano-hydroxyapatite.It provides a simple,green and efficient method for the preparation of inorganic nanomaterials and inorganic nanomaterials/natural polymer composites.In this paper,the preparation and properties of nano-hydroxyapatite and its composite based on ionic liquid were mainly studied.Firstly,nano-hydroxyapatite was synthesized by reflux-hydrothermal method using ionic liquid 1-butyl-3-methylimidazolium bromide([Bmim]Br)and 1-allyl-3-methylimidazolium chloride([Amim]Cl)as templates respectively.The effects of template dosage,template type and preparation method on the preparation of nano-hydroxyapatite were investigated.Then ionic liquid circulation guided synthesis of nano-hydroxyapatite.The experimental conditions were optimized and the optimal synthesis process was determined.Nano-hydroxyapatite/microcrystalline cellulose composite(HA/MCC)were prepared by using ionic liquid[Amim]Cl as solvent and dispersant.The morphology,structure,mechanical properties,hydrophilicity,thermal stability,phenol adsorption properties and mechanism of the composites were studied.The results showed that:(1)Nano-hydroxyapatite was successfully prepared by ionic liquid as a green template combined with reflux-hydrothermal method.The HA nanorods prepared by the ionic liquid[Amim]Cl as a template have a length of 30-60 nm,a diameter of 20-30 nm,and have pits with a diameter of 2-6 nm on the surface.The ratio of calcium to phosphorus is 1.69,the specific surface area is 94.50 m2/g,the pore volume is 0.40 cm3/g,and the pore size mainly distribution is at 5.5 nm.(2)A nano-hydroxyapatite/microcrystalline cellulose composite was prepared by using ionic liquid[Amim]Cl as solvent and dispersant.With the increase of HA content,the structure of the composite gradually became loose and the hydrophilicity was continuously enhanced;When HA content was 3%,the tensile strength of the composites reached the maximum,65.23 MPa,which was 18.4%higher than that of pure MCC materials,and the thermal stability of the composite was improved to some extent by adding nano-HA.(3)Phenol adsorption experiment showed that the adsorption effect was the best when the nano-HA content was 20%,the adsorption amount was 6.59 mg/g,the phenol removal rate was 52.68%.The composite material reached adsorption equilibrium at 120 min,and the adsorption process f,ollowed pseudo second order kinetic model.(4)The ionic liquid as the HA template and MCC solvent can be recycled and reused.The cycle-oriented synthesis nano-HA still has good crystallinity and purity,and the reflux-hydrothermal and blending process does not have a great impact on the structure of the ionic liquid.