【作者】 倪博立；

【导师】 柳明珠；

【作者基本信息】 兰州大学 ， 高分子化学与物理， 2012， 博士

【摘要】 随着人类对环境、健康以及自然资源可持续利用等的关注不断提高,在保证粮食产量的同时,最大限度地减少肥料损失、提高肥料利用率,是当前农业肥料科技创新的重要任务,也是实现农业可持续发展的重要保证。本学位论文着眼于开发高效、环保、低成本的多功能缓控释肥料,以无机矿物凹凸棒黏土为基质,尿素、硫酸铵、氯化铵和磷酸二氢钾等为化肥原料,海藻酸钠、瓜尔胶、淀粉及其衍生物、纤维素衍生物、腐植酸、聚丙烯酸、聚衣康酸、聚丙烯酰胺等天然高分子和合成高分子为包膜原材料,采用圆盘造粒的工艺制备了一系列多功能有机/无机复合包膜型缓控释肥料；对多功能肥料样品的养分缓控释行为、缓控释机理、对土壤的调理作用,以及包膜材料的降解性等多方面进行了系统研究,具体内容如下：1.将尿素、磷酸二氢钾和焦磷酸铜钾包埋于交联的海藻酸钠中,以此作为肥料内核,保水剂海藻酸钠-g-聚丙烯酸作为肥料颗粒包膜材料,制备了一种具有保水功能的多元缓释肥料。所制备的接枝聚合物SA-g-PAA作为肥料的包膜材料,既可以起到减缓肥料养分释放的作用,又可以有效降低土壤中水分的蒸发率,提高土壤的保水性。将天然高分子海藻酸钠引入到保水剂的制备中,可以改善保水剂的降解性能。合成了一种低水溶性化合物焦磷酸铜钾,具有非常好的缓释效果,可以作为一种长效铜肥使用。2.将尿素和磷酸二氢钾包埋于凹凸棒黏土基质中,以此作为肥料内核,海藻酸钠作为内层包膜,保水剂海藻酸钠-g-聚(丙烯酸-co-丙烯酰胺)/腐植酸作为外层包膜,制备了一种双层包膜的多功能缓释肥料。凹凸棒黏土不仅具有较强的吸附功能,而且元素含量丰富,因此,作为肥料的组成部分不仅可以起到缓释的作用,还可以提供多种营养元素。使用天然高分子海藻酸钠作为包膜材料,不仅工艺简单,而且可以对养分产生一定的缓释效果。将所制备的保水剂材料海藻酸钠-g-聚(丙烯酸-co-丙烯酰胺)/腐植酸作为外层包膜材料,不仅起到了减缓肥料养分释放速率和提高土壤持水能力的作用,而且还可以调节土壤的酸碱性。3.将尿素和磷酸二氢钾包埋于凹凸棒黏土基质中,以此作为肥料内核,瓜尔胶作为肥料内层包膜,保水剂瓜尔胶-g-聚(衣康酸-co-丙烯酰胺)/腐植酸作为外层包膜,制备了一种多功能有机/无机复合缓释肥料。使用环境友好型的亲水性聚合物瓜尔胶作为包膜材料,利用其较大的粘度特性来控制肥料养分的释放。在保水剂瓜尔胶-g-聚(衣康酸-co-丙烯酰胺)/腐植酸的制备中,瓜尔胶和腐植酸的引入不仅提高了产品的吸水能力,降低了成本,改善了其降解性能,而且腐植酸还是一种很好的有机肥成分。将该保水剂材料作为肥料的外层包膜,在控制肥料养分的释放、改善土壤的水分状况和pH值方面起到了较好的效果。4.以乙基纤维素为肥料的内层包膜,羧甲基纤维素/羟乙基纤维素复合保水剂为外层包膜制备了一种环境友好型包膜氮肥。基于乙基纤维素的疏水性和成膜性,将其作为肥料的内层包膜,起到了较好的缓释效果。此外,合成的可完全生物降解的羧甲基纤维素/羟乙基纤维素复合保水剂作为肥料的外层包膜,在其吸水溶胀的过程中也可以对营养元素进行吸附,既起到了缓释的作用又对土壤持水和保水能力的提高产生了明显的效果。5.以淀粉为原料合成了取代度为2.8的高取代度醋酸酯淀粉,以此作为颗粒肥料的内层疏水性包膜材料,以羧甲基淀粉和黄原胶为原料,在三偏磷酸钠交联条件下,制得一种新型的农用保水剂材料,以此作为颗粒肥料的外层包膜材料,制备了一种新型多功能缓控释肥料。通过控制包膜量和加入增塑剂来改善醋酸酯淀粉膜的性能,进而来控制肥料养分的释放速率,从而达到养分的可控释放。羧甲基淀粉/黄原胶复合保水剂作为包膜材料不仅可以提高土壤的持水能力,而且,由于该新型保水剂的组成都是天然高分子材料,降解后还可作为一种有机肥增加土壤的有机质含量,改善土壤肥力。6.通过包肥法在一定条件下的土壤中对所制备的几种多功能缓控释肥料的缓释性能进行研究,结果发现,使用亲水性高分子材料海藻酸钠和瓜尔胶作为肥料的内层包膜,尽管包膜工艺简单,但在缓释性能上不及疏水性的乙基纤维素和醋酸酯淀粉。将一定比例的多功能肥料施入土壤后,对土壤的持水能力和保水能力进行考察,结果发现,所制备的保水剂材料在改善土壤水分状况方面有明显的效果,但使用纤维素衍生物和淀粉衍生物所制备的羧甲基纤维素／羟乙基纤维素和羧甲基淀粉／黄原胶复合保水剂材料,由于全部采用环境友好的天然高分子作为原料,在一定程度上减轻了保水剂对石油相关产品的过分依赖,具有不污染土壤环境、成本低等优点,有望得到推广应用。本学位论文选择来源广泛、价格低廉、无污染且又能保证肥料具有较好缓控释性的包膜材料,采用简单的制备工艺,制备了一系列环境友好型有机／无机复合的多功能缓控释肥料,对其多方面的性能进行了系统地评价和研究,这将为拓展包膜型缓控释肥料的种类、促进其推广应用奠定一定的理论和实际应用基础。更多还原

【Abstract】 With the increasing public concern toward human health, environmental protection, and natural resource sustainability, there is a shift toward the development of sustainable agriculture that sustains food production with minimal fertilizer nutrient loss. This is an important task of the scientific and technological innovation of agricultural fertilizers. This thesis focuses on the development of efficient, environmentally friendly, low cost multifunctional slow/controlled release fertilizers, based on attapulgite clay as matrix, urea, ammonium sulfate, ammonium chloride, and potassium dihydrogen phosphate as fertilizer raw materials, sodium alginate, guar gum, starch and its derivatives, cellulose derivatives, humic acid, poly(acrylic acid), poly(itaconic acid), polyacrylamide, etc. as coating materials. Granulator was used to prepare a series of multifunctional organic-inorganic coated slow/controlled release fertilizers. The release behavior and mechanism of the products, the influence of the products on soil conditioning, as well as the degradation of the coating materials were determined systematically. The main results are as follows:1. A slow-release multielement compound fertilizer (SMCF) was prepared. The nutrients (H2NCONH2, KH2PO4, and K2Cu3(P2O7)2·3H2O) were entrapped in the alginate matrix granules, and the crosslinked sodium alginate-g-ploy(acrylic acid)(SA-g-PAA) superabsorbent polymer was used as coating. The product could significantly improve the water-holding capacity and decrease the moisture evaporation of soil. Moreover, the partially degradable superabsorbent materials used as coating can alleviate the pollution which was caused by conventional non-degradable superabsorbent polymer materials. The nutrient Cu in K2Cu3(P2O7)2·3H2O showed excellent slow-release property, which is available in the soil so as to be assimilated by plants for a long period.2. A multifunctional double coated slow release fertilizer was prepared based on nutrients urea and potassium dihydrogen phosphate entrapped in the attapulgite clay matrix, sodium alginate used as an inner coating and sodium alginate-g-poly(acrylic acid-co-acrylamide)/humic acid superabsorbent polymer used as an outer coating. The introduction of APT can slow fertilizer nutrients release due to its adsorption capacity and provide abundant nutrients. Natural polymer sodium alginate as coating materials, not only made the process simple, but also can slow fertilizer nutrients release. The superabsorbent used as outer coating not only slowed down the nutrient release, improved water-holding capacity of soil, but also regulated the pH value of soil.3. A multifunctional slow release organic-inorganic compond fertilizer was prepared based on nutrients urea and potassium dihydrogen phosphate entrapped in the attapulgite clay matrix, guar gum used as an inner coating and guar gum-g-poly(itaconic acid-co-acrylamide)/humic acid superabsorbent polymer used as an outer coating. The use of environmentally friendly hydrophilic polymer guar gum as coating materials played a role in controlling nutrient release to some extent based on its high viscosity. The introduction of guar gum and humic acid in the preparation of the superabsorbent polymer guar gum-g-poly(itaconic acid-co-acrylamide)/humic acid not only enhanced water absorption capacities, reduced the cost, improved its degradability, but also provided a kind of organic fertilizers for plant growth. The superabsorbent used as outer coating played an important role in slowing down the nutrient release, improving water-holding capacity of soil, and regulating the pH value of soil.4. An environmentally friendly coated nitrogen fertilizer was prepared based on ethyl cellulose as an inner coating, carboxymethyl cellulose/hydroxyethyl cellulose composite material as an outer coating. Ethylcellulose played an important role in slowing down the nutrient release due to its hydrophobicity and excellent film-forming ability. The degradable composite absorbent material carboxymethyl cellulose/hydroxyethyl cellulose used as outer coating materials can adsorb the nutrition element in the process of absorbing water, which was helpful in retarding nutrient release, improving water-holding and water-retention capacity of soil.5. A controlled release fertilizer system based on starch acetate with high degree of substitution and weakly cross-linked carboxymethyl starch/xanthan gum absorbent with trisodium trimetaphosphate as coating materials was developed to improve fertilizer use efficiency. The N release can be controlled by changing the thickness of coating and the content of plasticizer. The polysaccharide based absorbent material carboxymethyl starch/xanthan gum used as a novel coating played an important role in holding water in soil. Moreover, when the absorbent material was degraded, it can be used as an organic fertilizer to increase soil organic matter content and improve soil fertility.6. The nutrient release behaviors of the several multifunctional slow/controlled fertilizers were determined by burying an amount of products in sealed plastic mesh bags in the soil. The results showed that although the processing is simple with the hydrophilic polymer sodium alginate and guar gum used as inner coatings, the slow release properties were compromised compared with ethyl cellulose and starch acetate. The results of the effect of the multifunctional fertilizer products on water-holding and water-retention capacity of soil showed that, the absorbent materials we prepared played an important role in holding water in soil. Moreover, the composite absorbent materials carboxymethyl cellulose/hydroxyethyl cellulose and carboxymethyl starch/xanthan gum were prepared based on environmentally friendly natural polymer, which could reduce the excessive reliance on petroleum-based products of superabsorbents to some extent. The products with the characteristics of non-polluting and low-cost could be expected to have wide applications.In conclusion, several kinds of environmentally friendly multifunctional slow release organic-inorganic compond fertilizer were prepared in a simple process by using the coating materials with extensive source, low cost, and non-polluting properties. The structural and chemical characteristics of the products, as well as the aspects of performance were examined. This work will lay the theoretical and practical foundation to some extent for expending the types of coated slow/controlled fertilizers and promoting the practical applications.更多还原