Enhanced efficiency fertilisers: a review of formulation and nutrient release patterns

Fertilisers are one of the most important elements of modern agriculture. The application of fertilisers in agricultural practices has markedly increased the production of food, feed, fuel, fibre and other plant products. However, a significant portion of nutrients applied in the field is not taken up by plants and is lost through leaching, volatilisation, nitrification, or other means. Such a loss increases the cost of fertiliser and severely pollutes the environment. To alleviate these problems, enhanced efficiency fertilisers (EEFs) are produced and used in the form of controlled release fertilisers and nitrification/urease inhibitors. The application of biopolymers for coating in EEFs, tailoring the release pattern of nutrients to closely match the growth requirement of plants and development of realistic models to predict the release pattern of common nutrients have been the foci of fertiliser research. In this context, this paper intends to review relevant aspects of new developments in fertiliser production and use, agronomic, economic and environmental drives for enhanced efficiency fertilisers and their formulation process and the nutrient release behaviour. Application of biopolymers and complex coacervation technique for nutrient encapsulation is also explored as a promising technology to produce EEFs. © 2014 Society of Chemical Industry     

Applying fractography and fracture mechanics to the energy and mass of crack growth for glass in the mirror region

The mirror region following the fracture initiation site is considered by applying fracture mechanics principles along with experimental observations of the crack velocity at the formation of the mirror mist boundary. Several issues regarding this crack growth in glass are addressed after considering the terminal velocity of crack growth and the mirror mist boundary information on silicate glasses. A strain energy release rate criterion is applied to estimate the kinetic energy of an advancing crack in glass at the mirror/mist boundary. This energy is then utilized to estimate the effective mass of the crack at the mirror/mist boundary. It is compared with material volumes in the vicinity of the crack.     

土壤和沉积物中磷素释放过程的影响因子分析

磷素是水体富营养化的限制性因子,土壤和底泥沉积物中磷素的释放和水体中磷素的迁移转化,都会对水体富营养化产生影响。磷素的最终释放量是物理、化学及生物因素共同作用的结果。文章从影响磷素释放的影响因子入手,系统分析影响磷素释放的关键因子,研究其在磷素释放过程中所起的作用,为研究磷素在水-土介质及水-沉积物界面中的迁移转化提供依据。     

激光粒度仪分级测定水煤浆粒度分布的研究

为确定多种磨矿产品级配制得水煤浆样品的粒度分布,文章提出了分级测定水煤浆粒度的方法,已知各磨矿产品的粒度分布,通过分级拟合的方法得到不同质量比级配样品的粒度分布。结果表明:分级计算方法得到的煤样粒度分布可以准确反映出级配样品的峰型,且粒度测试结果较为准确。     

不同因素对HAP-尿素缓释肥中养分释放性能的影响

以羟基磷灰石(HAP)作为载体材料制备羟基磷灰石-尿素缓释复合肥,利用DMAB显色法检测尿素的含量,考察温度、肥水比、pH值对HAP-尿素复合物养分在水中释放率的影响,复合物在水中溶出养分释放率最佳条件是:肥水比为1∶20,温度为30℃,pH值为7。     

包膜尿素总氮含量测定方法的改进

采用经典的凯氏定氮法[1]对包膜型控释尿素总氮含量的测定,试样需经过消解、蒸馏、滴定三个操作步骤。该方法分析人员在操作过程中稍有不慎易导致误差,分析速度慢。改用KDY-9830型凯氏定氮仪法可减少或避免分析人员操作误差,分析速度较快。用该方法测定包模型控释尿素样品中总含氮量与用国标法(GB/T23348—2009)测定的相比,结果相差小于0.5%。KDY-9830型凯氏定氮仪法较经典的凯氏定氮法操作简便、快速、导致误差的几率少,测定数据稳定可靠,且可进行大批量样品的测定。     

用湿法磷酸生产工业级磷酸二氢钾工艺技术的研究

研究用湿法磷酸中和法制备工业级磷酸二氢钾的工艺过程,主要研究了反应终点p H对净化效果及磷收率的影响,以及磷酸浓度对磷收率的影响。研究结果表明:当反应终点溶液p H达到3.96时,铁、铝和氟脱除较完全,钙脱除率其次,镁脱除率较低;磷酸浓度升高,磷收率降低,反应终点p H升高,磷收率也有所降低;在实验条件下,磷酸二氢钾溶液经浓缩、冷却结晶后得到的磷酸二氢钾产品w(KH2PO4)可达99%以上。     

水性丙烯酸酯乳液包膜尿素研究

水性聚合物乳液包膜肥料技术在提高肥料利用率、有效控制农业污染方面发挥重要作用。采用预乳化半连续滴加的种子乳液聚合工艺合成水性丙烯酸酯乳液、高压喷枪喷涂包裹尿素制得包膜尿素;讨论了不同聚合硬软单体质量比、油水质量比、引发剂用量、乳化剂用量对乳液性质及包膜效果的影响,当聚合硬软单体质量比为48.0∶52.0、油水质量比为100∶120、w(引发剂)为0.5%、w(乳化剂)为2.4%时,包膜尿素缓释性较好。     

微/纳米药物给药系统的研究进展

在过去的几十年中,探索高效的微/纳米给药系统一直是药剂学领域的研究热点。不同的微/纳米颗粒已被用于药物输送的研究,以期实现有效靶向给药,最大限度地减少副作用,从而提高治疗效果。本文主要综述了微/纳米药物输送给药系统及在药物制剂领域应用。     

鄂尔多斯盆地B区延长组长8储层四性关系及有效厚度下限研究

通过岩心、试油和分析化验等资料并结合测井资料,对鄂尔多斯盆地B区延长组长8储层进行"四性"关系研究。研究结果表明长8储层岩性主要为浅灰、深灰色细粒—极细粒长石岩屑砂岩或岩屑长石砂岩,成分成熟度较低而结构成熟度较高;储集空间以溶蚀孔隙为主,属于低孔、特低渗储层,岩性、物性的差异控制了储层油气的富集程度。确定了其储层物性下限标准为:孔隙度为7.5%,渗透率为0.15×10-3μm2;电性下限标准为:电阻率为31Ω·m。声波时差为220μs/m;含水饱和度小于等于62%。该研究为以后的油气勘探与开发工作提供了理论依据。