Application Of Superhydrophobic Surface In Liquid Distributor And Its Process Intensification Studies

Rotating packed bed(RPB)is a reactor with outstanding micromixing performance.However,when it is applied in the manufacture of pharmaceutical,cosmetics and fine chemicals with low liquid flow rate,liquid cannot be flow out from liquid distributor continuously,and such dripping flow pattern will decrease the micromixing performance and affect the product quality.Liquid distributor,as a vital part of RPB,plays an important role on the micromixing performance of the reactor.Herein,in order to change the liquid flow pattern under low liquid volumetric flow rate,this thesis proposed to change the wettability of liquid distributor by applying superhydrophobic coating.The effect of liquid distributor with different wettability on miromixing efficiency of RPB and the mean diameter of calcium carbonate particle were investigated.This novel strategy is expected to provide a reference to apply RPB in manufacture industry with low liquid flow rate.The main contents of this thesis are as follows:(1)Liquid distributor surface was covered smoothly by cooper foil,and chemical deposition method and low-surface-energy material were used to fabricate superhydrophobic coating on its surface.The water contact angle of superhydrophobic coating was around 154.6°.When the liquid volumetric flow rate ranged between 3.0 mL/min and 3.8 mL/min,liquid can be sprayed out from liquid outlet of the liquid distributor continuously with relative high velocity by using surface-modified liquid distributor.(2)By adopting competitive-parallel reaction system of iodide-iodate,the micromixing performance of RPB with liquid distributors of different wettability was investigated.Under the same experimental conditions,RPB with surface-modified liquid distributor has better micromixing efficiency.According to the incorporation model,its micromixing characteristic time was calculated as 1.5×10-6 s to 3.6×10-6 s.Compared with liquid distributor without superhydrophobic coating,the micromixing characteristic time was decreased by one order of magnitude.(3)Ultrafine calcium carbonate particle was prepared in RPB by adopting sodium carbonate-calcium chloride system.Under the same experimental conditions,the mean calcium carbonate particle diameter prepared with the surface-modified liquid distributor was about 1.23 ?m,which was much smaller than that with liquid distributor without superhydrophobic coating.