Controlled Release of Ammonium Nitrate from Ethylcellulose Coated Formulations

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• 作者：Susana Pé ; rez-Garcí ; a ; Manuel Fern&aacute ; ndez-Pé ; rez ; Matilde Villafranca-S&aacute ; nchez ; Emilio Gonz&aacute ; lez-Pradas ; Francisco Flores-Cé ; spedes
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2007
• 出版时间：May 9, 2007
• 年：2007
• 卷：46
• 期：10
• 页码：3304 - 3311
• 全文大小：701K
• 年卷期：v.46,no.10(May 9, 2007)
• ISSN：1520-5045

文摘

Different ammonium nitrate controlled-release (CR) systems based on ethylcellulose have been investigatedto reduce environmental pollution derived from nitrogen-fertilizer use. Coated ammonium nitrate granuleswere produced in Wurster-type fluidized-bed equipment using two different amounts of ethylcellulose. Thehighest one was modified by the addition of two plasticizers, dibutyl sebacate, and dibutyl phthalate. Havingresearched the encapsulation efficiency and the homogeneity of the coated granules, we carried out the kinetic-release experiments in water and soil. The release rate of the active ingredient was related to the thickness ofthe coating film, granule size, and type of plasticizer used. Using an empirical equation, the time taken for50% of the active ingredient to be released into water and soil (T₅₀) was calculated. From the analysis of theT₅₀ values, we can deduce that the release rate of ammonium nitrate can be controlled, mainly changing thethickness of the coating film and using plasticizer as well. In water experiments, T₅₀ values for granulesprepared without plasticizers ranged between 7.47 h for 1 mm < d < 2 mm granules coated with 10% ofethylcellulose and 24.06 h for 2 mm < d < 3 mm granules coated with 20% of ethylcellulose. For thoseprepared with plasticizers, T₅₀ ranged between 22.80 h for 1 mm < d < 2 mm granules containing dibutylsebacate and 35.74 h for 1 mm < d < 2 mm granules containing dibutyl phthalate. However, in soil experimentsT₅₀ values ranged between 10.24 h for 1 mm < d < 2 mm granules coated with 10% of ethylcellulose and38.80 h for 1 mm < d < 2 mm granules containing dibutyl sebacate. Finally, a linear regression of the T₅₀values was obtained by the results of the study carried out in water and soil. This allows us to predict thebehavior of the formulations in soil. This could be useful in the design of systems which control the nitrogenrelease.