Study On Modified Attapulgite/Fe₃O₄ Composite And Synthesis On Neotame-calcium Chelate

In this work, Fe₃O₄ nanoparticles were prepared by chemical co-precipation and then were loaded by attapulgite. Attapulgite/Fe₃O₄ we have gotten were modified by KH-550.The surface organic modified attapulgite/Fe₃O₄ were characterized by IR,XRD,TEM,VSM. Take lipase as the research object to study enzyme immobilization on the modified attapulgite/Fe₃O₄ composites by cross-linking adsorption. The effort of lipase immobilization was determined by lipase activity and amount of lipase immobilized on modified attapulgite/Fe3O4 composites. The influencing factors on lipase immobilization were studied by single factor experiments: immobilization pH, immobilization time and temperature.The results show that attapulgite/Fe₃O₄ composites have been successfully coated by silane coupling agent KH-550. TEM transmission photos reveales that the composite particles have approximatly spherical structure, uniform size and good dispersion. XRD peaks shows the modified Fe₃O₄ composites have an excellent crystal structure. The modified composite fully retained crystal diffraction peaks of magnetic Fe3O4 particles. The diameter of particles was calculated by Scherrer equation, Fe₃O₄ nanoparticle size is about 9.3nm, while the modified attapulgite/Fe₃O₄ particles have increased to 50nm. The saturation magnetic intensity of magnetic nanoparticles Fe3O4 prepared by chemical co-precipation is 78.271emu/g and the modified attapulgite/Fe₃O₄ composite is 16.097 emu/g both with superparamagnetism. The organic modified attapulgite/Fe₃O₄ acts as carriers to fix lipase by cross-linking adsorption with glutaraldehydethe. The optimum process conditions were studied by single factor experiments: immobilization pH is 5, temperature is 50℃and time is 3h, the product obtained on these conditions has a better property with immobilized lipase activity 121u/g, amount of loading 108.08mg/g, saturation magnetization 13.788emu/g and also has with superparamagnetism.In addition, we also studied the nutritional additive and successfully synthesized the neotame-calcium chelate from neotame and calcium carbonate as raw materials. The optimum technological conditions were determined by single factor experiments and orthogonal experiments, the molar ratio of neotame to calcium carbonate is 1:2, the reaction temperature is 90, the time is 3h. The chelate was characterized by elementary analysis, IR, TG, XRD, the results indicated that neotame and calcium had a successful ligand with an excellent crystal form, the calcium accounted for 9.2% in the chelate and the inferred composition was Ca(C₂₀H₃₀N₂O₅)·H₂O.