磷酸氢钙包膜尿素的研制及其释放特性

Development of calcium hydrogen phosphate coated urea and its release characteristics

以聚乙烯醇水溶液为粘结剂,以肥料级磷酸氢钙为包膜材料,采用喷雾包涂的方法制备一种新的、多营养的、不污染土壤的缓释/控释尿素。用水浸泡法和土壤培养法表征了包膜尿素的释放特性,用扫描电子显微镜研究了包膜尿素的表面和截面形貌。讨论了涂层量对包膜尿素的缓释性能的影响。实验结果表明:涂层量是影响尿素释放的重要因素,磷酸氢钙包膜尿素在水中氮素的释放行为可用一级释放动力学方程来描述;CU-25和CU-30包膜尿素在水中溶出80%的氮素分别需要5.36 d和12.53 d,而在土壤中溶出80%的氮素所需要的时间大于110 d;包膜尿素的扫描电镜照片显示,包膜层中的缝隙小于1μm。

A series of poly-nutrient and slow release/controlled novel urea, which were harmless to soil, were made by using fertilizer-grade calcium hydrogen phosphate as coating material and PVA water solution as adhesive. The release characteristics of coated urea were determined by means of water marinating and soil incubation. Surface and cross-section topography of the urea were detected by scanning electronic microscopy. The experimental results indicate that coating proportion was the domain factor controlling the release rate of the urea. The results of regression of release data showed that the N-release process of CaHPO4 coated urea could be fitted by the first-order release kinetics; it will take 5.36 d and 12.53 d to release 80% N in water for CU-25 and CU-30 fertilizers respectively, while in the soil it will take over 110 d; the SEM results for the coated urea showed that the aperture in the membrane was less than 1 μm.