| Based on the cross-linking reaction between chitosan and glutaraldehyde, the porous sustanied-release microspheres as a carrier for nutrient absorption of plant roots were prepared by emulsion chemical cross-linking method. It was investigated the effects of several factors including chitosan concentration, oil-water volume ratio(VO/VW), rotational speed, emulsification temperature, as well as volume ratios of hole agent dibutyl phthalate (DBP) and crosslinking agent glutaraldehyde on the formation of the porous microspheres. And the optimal process parameters were determined. The morphology and structure of the composite microspheres were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The sustained-release properties of the composite microspheres were detected by elemental analysis (EA) and inductively coupled plasma-atomic emission spectroscopy(ICP-AES). And the practical application of the novel sustained-release materials was examined.The results show that the spherical regularity of the prepared composite microspheres is the most excellent under the conditions of 1.8-2.0 wt% of chitosan solution,5:1 of VO/VW ratio, 900 r/min of stirring speed,45 ℃ of emulsification temperature, 1:7.5 of volume ratio of DBP to O/W and 1:40 volume ratio of 50% (v/v)glutaraldehyde to O/W. The average particle size of microspheres is about 50 μm,and nitrogen, phosphorus, potassium compound fertilizer was successfully wrapped in the microshperes. The results of sustained-release dynamic indicate that the carrier structure has greatly improved the absorption efficiency of compound fertilizer by plant flora.And the release gradually becomes stable after 132 hours which conforms to the Higuchi skeleton model and also indicates that the prepared composite microspheres have good sustained-release effect. Meanwhile the single factor study was further carried out, and the results show that the sustained-release effect was the most obvious for plant flora when appropriate amount of porous composite microspheres was added to the succulent plant.In summary, this dissertation provides a new preparation method for compound fertilizer carrier, which has the properties of easy biodegradation and excellent sustanied-release, and will have great application prospect in plant cultivation. |
