包膜型尿素缓释肥料发展动向

本文综述了包膜型型素缓释肥料的国内外发展动向。     

以松香和桐油为成膜物质的包膜尿素的释放特性和表面形貌

以松香和桐油为成膜物质制备了一系列包膜尿素,用浸泡溶解法和无土柱淋溶法表征了所得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形貌,讨论了涂覆成分、涂覆层数、密封层对包膜尿素释放特性的影响。采用双层涂覆和单层外密封工艺制备的包膜尿素其一天溶解释放率为12.7％,释放周期大于11天,累积释放率为80％。     

石蜡-天然松香包膜尿素的研制

以石蜡 -天然松香作为包膜材料 ,采用熔融喷雾包涂的方法制备控制释放尿素 ,并讨论了松香与石蜡的配比、涂层量和操作条件对包膜尿素养份释放速率的影响。实验结果表明 :涂层中松香的含量及包膜量 (膜厚 )是影响包膜尿素养份释放速率的主要因素。     

可生物降解PBS包膜尿素缓释肥料的制备与性能研究

研究可生物降解PBS包膜尿素缓释肥料的制备与性能。以可生物降解PBS为包膜材料,通过循环流化床工艺制备PBS包膜尿素缓释肥料,经过对制备工艺进行优化,确定包膜剂PBS质量分数为5%、二次流化时间为20 min、包膜率为10%的PBS包膜尿素具有良好的缓释效果,其初期释放率为10%,第28天时累积释放率为72%,基本符合缓释肥料标准。     

聚氨酯包膜控释尿素制备工艺与养分释放特性研究

4,4'-二苯基甲烷二异氰酸酯(MDI)与植物油多元醇均匀喷涂在流化状态的尿素颗粒表面并发生化学反应,形成聚氨酯膜层。以侧喷流化床包膜工艺为基础,通过研究包膜量、反应温度、反应物比例等不同工艺条件下包膜尿素的养分释放性能,获得的生产聚氨酯包膜尿素的最佳工艺条件为反应温度75℃、MDI与植物油质量比1.0:1.0、反应时间20 min、催化剂用量0.40%(质量分数)、包膜比率为4.0%(质量分数),此包膜控释尿素的养分释放周期可达70 d。     

包膜尿素控制释放过程传质模型

根据质量守衡定律和F ick扩散定律建立了包膜尿素控制释放过程的传质模型,并用3种新颖的石蜡-松香混合物包膜尿素在蒸馏水中的释放数据和扫描电镜照片对模型进行了验证。结果表明,该模型能有效地描述和预测由扩散机制控制的包膜尿素的养分释放行为,拟合的相关系数R2分别为0.997 6,0.997 3和0.998 4。模型显示,包膜尿素的养分释放速率与膜的有效扩散系数Deff成正比,与尿素粒径的平方及膜的厚度成反比。     

超薄可降解聚氨酯包膜尿素的快速检测方法

采用静水溶出率法,在不损伤包膜的情况下,找出高温（50℃）静水浸提树脂包膜尿素与常温（25℃）静水浸提时间的相关系数。结果表明：通过50℃静水浸提来检测相应指标,可以有效缩短缓释肥料国家标准（GB／T23348-2009）和控释肥料行业标准（HG／T4215-2011）采用的25℃静水浸提检测所需的时间;树脂包膜尿素养分累积释放曲线相关系数均≥0．9900,呈极显著水平;检测时间只需8—10d,测量误差范围在2％-3％。     

桐油包膜尿素单个颗粒养分释放行为的研究

桐油包膜尿素单个颗粒的养分表现出3个阶段释放规律,即时滞期、线性释放期和衰退释放期,养分释放具有由扩散机理支配的S形逐步释放特征。尽管粒径和包膜厚度存在差异,包膜尿素单个颗粒的养分释放不同。但是由30-90颗包膜尿素颗粒构成的6个包膜尿素颗粒群的养分释放行为却非常接近。     

脲醛树脂包膜尿素的制备研究

介绍了脲醛树脂包膜尿素的制备方法,研究了脲醛树脂及植物油用量对脲醛树脂包膜尿素氮初期溶出率的影响。结果表明,包膜量越多,包膜尿素氮的溶出率越低,但使用脲醛树脂直接包膜尿素的方法并不理想;先使用植物油在尿素颗粒的表面包一层油膜,再使用脲醛树脂包膜,可大幅度降低包膜尿素氮的溶出率,在使用1.0%的植物油后,树脂包膜量为15%时,氮的初期溶出率即可低于40%,大大降低包膜材料的使用量。     

脲醛缓释肥在橡胶树上的肥效研究

通过试验研究了脲醛缓释肥、脲醛缓释肥加尿素及尿素等6个养分投入量相同的处理对橡胶树胶水产量的影响.试验结果表明,施用脲醛缓释肥,提高了橡胶树胶水产量,以肥料中掺混60％脲醛缓释肥和40％普通尿素一次性施用效果最好,既降低了施用脲醛缓释肥的成本,又节省了劳动力.     

脲醛缓释肥料在水稻上的应用研究

对脲醛缓释肥料在水稻上的应用进行肥效试验。结果表明:施用脲醛缓释肥料可延长水稻生育期5~7 d;有效提高分蘖苗数、有效穗和株高,增加总粒数和实粒数,降低空秕率,提高千粒质量;增产增收效果明显,增产幅度达4.73%~10.22%,每667 m2增加纯收益21.52~86.62元。     

重量法测定脲甲醛缓释肥料活性指数的研究

研究重量法测定脲甲醛缓释肥料的活性指数,对重量法和行业标准HG/T 4137—2010指定测定方法测定结果进行相关性研究。结果表明,两种方法的测定结果存在极显著正相关性,相关系数为0.996 6,两种方法测定值的绝对差值范围为-0.85%~0.56%。重量法具有简便、高效和准确的特点,可替代HG/T 4137—2010中脲甲醛缓释肥料活性指数测定方法。     

尿素过磷酸钙复肥生产工艺

介绍了尿素过磷酸钙（USP）复肥的主要生产工艺过程及条件,认为USP复肥是普通过磷酸钙（SSP）生产厂理想的升级产品。     

Parametric study of tumbling fluidized bed to evaluate nitrogen release characteristics of biopolymer-coated controlled release urea

To impede nitrogen loss due to leaching and NH₃ volatilization, pristine urea particles are coated with synthetic polymers such as poly(acrylic acid) and polyethylene for the controlled release of nitrogen. However, due to nonbiodegradability and environmental and economic issues, these synthetic polymers are replaced with cheap, biodegradable, and green coating materials. In this study, borax-modified starch biopolymer is used to produce controlled release urea (CRU) in a tumbling fluidized bed. Central composite rotatable design is used to study the interactive effect of process parameters on time and kinetics of nitrogen release. Nitrogen release in distilled water is monitored by the UV–Vis spectrophotometer and soil burial test is used to observe release in soil. The optimum values of process parameters and response objectives generated by the analysis of variance are validated by triplicates of confirmation runs and the % error is reported as a precision indicator. A mathematical model is used to determine the diffusion coefficient of nitrogen release. Biopolymer-coated urea results in much better release performance when compared with starch-based CRU reported in the literature. The most influential process parameter both for time and kinetics of nitrogen release appears to be the coating time. Release time increases linearly with coating time and the diffusion coefficient decreases with increase in coating time. The kinetic study reveals that some of the samples followed non-Fickian diffusion and others followed Case-II transport during the release of nitrogen.     

Factors affecting N release of urea from reactive layer coated urea

An experimental fertilizer called reactive layer coated urea (RLCU) has been developed by coating urea with a mixture of diisocyanate and polyol in the presence of a catalyst. The hard, durable layer that is formed on the granule conveys slow-release character to the product. A series of soil incubation tests were conducted under simulated upland conditions for periods up to 56 days to study the effect of factors such as temperature, pH, soil moisture, and organic C additions on N release. The N release rate from RLCU was shown to be increased with increasing temperature and decreasing coating thickness. It was unaffected by the addition of lime to raise the pH or organic carbon sources to increase microbial activity. Although a slight effect of soil moisture was noted, it was not pronounced. Urea release tended to be in two stages — a constant diffusive stage in which, it is postulated, urea was still dissolving within the granule and diffusing to the soil at a constant rate and a slower logarithmic stage where the rate of release decreased with time.     

低成本缓释化肥的实验室制备及其养分释放特征研究

研制了一种低成本缓释化肥,并对其养分缓释性能及养分释放规律进行了研究.实验结果表明:蒸馏水的作用无法使该缓释肥料中的大分子物质水解而释放出养分,而土壤则能使其养分基本释放,这说明该缓释肥料中的高分子物质能够在土壤中降解,作为化肥施入土壤后在一段时间内能够降解成能被植物吸收的小分子营养物质.     

可生物降解PBAT包膜尿素缓释肥料的制备与性能研究

以可生物降解PBAT为包膜材料,通过循环流化床工艺制备一系列PBAT包膜尿素缓释肥料,并对制备工艺进行了优化;通过扫描电镜观察包膜肥料表面形态特征,分析缺陷形成原因;通过水中静置法测试PBAT包膜尿素缓释肥料的缓释性能,测定缓释曲线,样品的初期释放率为20%~50%,第28天的累积释放率为70%~90%。