The Study Of The Preparation Technology And The Properties Of Fe₃O₄/AC Microcapsules

Taking the separation of products in industrial fermentation as the research background, the mild and efficient Impulsive Electrostatic Technique as the preparation technology, chitosan and sodium alginate as the carrier materials, Fe₃O₄ nanopowdes with superparamagnetic property as the magnetic material, The Fe₃O₄ / AC microcapsules are prepared. Its preparation process and membrane-forming reaction conditions are optimized. The paper make a prelimminary research on Fe₃O₄-loaded microcapsules immobilized cells and its magnetic responsiveness.Experimental results show that:1. The optimum conditions to prepare Fe₃O₄ / AC microspheres with Impulsive Electrostatic Preparation process are as follows: Voltage 375V, Frequency 0.05HZ, Pulse-width 2ms, concentration of algninate solution 22mg/mL, Fe₃O₄ consentration 0.003g/mL, pinhole aperture 700μm. The magnetic microcapsules has an efficency of 66.75%-73.59%.2. The optimum condition of the mebrane formation are as follows: chitosan molecular weight 5×10⁴, membrane formation time 15min, concentration of chitosan 1mg/mL. The particle size between 300-450μm are better to form stable microcapsule membrane. The introduction of Fe₃O₄ has no significant influence on the stability of the membrane.3. When Fe₃O₄-loaded microcapsules immobilized cells , the microcapsules are selective to the culture enviroment. The composition of peptone has a greate infulence on the memebrane stability. The probable reason that there is some multi-acid in pepton which destroyed the membrane stability.4. The introduction of Fe₃O₄ in the cell culture has no apparent influence on cell growth property. Fe₃O₄ has a good cell biocompatibility with the characteristics of magnetic material-oriented; The magnetic field around the systerm does not affect the microcapsules' magnetic responsiveness and the growth of B.licheniformis within it. The study prove the possibility of cells to separate on-line and achieve continuous operation with Fe₃O₄ /AC microcapsules.5. The optimum condition to prepare magnetic immobilized B.licheniformis are as follows: Fe₃O₄ consentration 0.003g/mL, the intial inoculation density of 1.5 times (6.25×10⁶ cells/mL), the average diameter of magnetic microcapsules are about 350μm.6. Cell metabolism has a shorter lag in microcapsules compared with free culture because of the mass diffusion effect of the microcapsule membrane. But the microcapsules can provide a steady micro-environment for cells. The experiment obtained higher cell biomass after four batch cultures with a fine microcapsule's shape. so it also prove that the membrane stability strong enough for the cell culture.