Study On Synthesis And In Situ Modification Of Typical Inorganic Nanomaterials By Microdispersion Device

Inorganic nano materials are the most important research field in nano materials,which are widely used in environment,energy,biology,etc.However,due to the characteristics of high activity,small particle size and high surface energy,inorganic nanoparticles are easy to agglomerate in the preparation process,resulting in the loss of due physical properties and functions of nanoparticles in the final application.Therefore,it is crucial to develop an efficient and controllable technique to synthesize inorganic nano materials.On the one hand,this situation can be improved by suitable equipment.Currently,membrane dispersion microreactors are widely used in the preparation of nanoparticles because of their good mixing performance and dispersion effect,which can enhance the mass and heat transfer of the reaction,and provide a homogeneous environment for the preparation of inorganic nanoparticles.In addition,it has the advantages of low energy consumption,high safety and easy scale-up.On the other hand,surface modification can be used to inhibit the agglomeration of nanoparticles and to prepare nanoparticles that are compatible with organic materials.Among them,the in-situ modification method is an ideal surface modification method,because the two processes of nanoparticle synthesis and surface modification are completed simultaneously,and it has the advantages of high production efficiency,low energy consumption,simple post-treatment and mild reaction conditions.Therefore,in this paper,the outstanding advantages of membrane dispersion microreactors in enhancing mixing,mass transfer and heat transfer are combined with in-situ surface modification technology to prepare inorganic nanomaterials with special application properties-nano calcium carbonate detergent and nano barium sulphate,and the main findings were as follows:(1)The technology can effectively control the rapid mixing and mass transfer of multiphase fluid,and realize the controllable preparation of nano-calcium carbonate detergent with high alkali value.The alkali value of the product is 377 mg KOH/g,and the average particle size of calcium carbonate in the product is 15 nm,with a narrow particle size distribution of 15±4 nm.(2)By adjusting the concentration of reactants and the feed flow,various morphologic nano-barium sulfate can be prepared,including square,leaf-shaped and sphere-like.When the feed flow rate was 20 m L/min and the concentration of reactant was 0.1mol/L,barium sulfate nanoparticles with a narrow particle size distribution and a particle size of about 100 nm were prepared.(3)The prepared barium sulfate nanoparticle films can meet the requirements of radiation cooling,and the solar reflectance can reach 96.89% in the band of 0.25～2.5 μm,and the emissivity can reach 80.7% in the band of 8～13 μm.