雾化状态对控释肥料膜结构和性能的影响

Effect of atomization on membrane structure and characteristics during manufacture of polymer-coated controlled-release fertilizer

利用喷雾相转化法将聚乙烯和石蜡溶于四氯乙烯的溶液喷射到处于流化状态的大颗粒尿素上,制备控制肥料养分释放的控释膜,系统地研究了喷雾-相转化-成膜过程中雾化状态对控释肥料膜结构和养分释放性能的影响。结果表明,随着雾粒粒径由43μm增加到120μm,膜的平均孔径由25.1nm增大到149.2nm,包膜尿素释放期从360d递减到96d;说明了雾化状态可影响相转化过程中的成膜结构和性能,膜的微孔结构可影响控释尿素的养分释放速率,即雾粒大小对膜结构和控释性能有十分重要的影响。为了获得达标的控释肥,必须将雾化颗粒控制在40～120μm的范围内,将膜的平均孔径控制在50～150nm范围内,才能获得预期的控释性能。

Controlled-release membrane was prepared based on the phase inversion method in which circulated urea particles were coated with polyethylene and olefin dispersed in tetrachloroethylene solution. The effect of atomizing on the membrane structure and nutrients release characteristics was investigated systematically. The results showed that as atomizing diameter changed from 43μm to 120 μm, the average pore diameter of membrane increased from 25.1 nm to 149.2 nm, thus, the release duration of nitrogen coated-urea dropped from 360 d to 96 d consequently. Atomizing diameter played an important role in the structure and characteristics of the membrane and atomizing influenced the membrane formation during phase inversion, therefore, nitrogen release rate of controlled-release urea was manipulated by the mini-pore structure of membrane. Furthermore, in order to obtain satisfactory release, the atomizing diameter should be optimized around 40--120 μm , and the ideal average diameter of the membrane pores should be in the range of 50--150 nm.