| 张菁,刘亚青.柠檬酸改性脲甲醛缓控释肥的制备及性能研究[J].广东农业科学,2023,(5):- |
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柠檬酸改性脲甲醛缓控释肥的制备及性能研究 |
| Preparation and performance study of citric acid modified urea formaldehyde slow release fertilizer |
| 投稿时间：2023-04-30 修订日期：2023-05-29 |
| DOI： |
| 中文关键词: 柠檬酸 脲甲醛 化学改性 缓控释 养分释放 |
| 英文关键词: citric acid urea-formaldehyde chemical modification slow and controlled release nutrient release |
| 基金项目:中央引导地方科技发展资金项目（YDZJSX2021B007）；聚合物基功能新材料山西省“1331工程”重点创新团队；山西省高等学校科技创新项目资助（2019L0585）；山西省应用基础研究计划项目（201901D211273） |
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| 摘要点击次数: 273 |
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| 中文摘要: |
| 【目的】为降低脲甲醛（UF）的初期养分释放速率，并提高中后期养分释放速率，采用柠檬酸（CA）对脲甲醛进行化学改性，改善UF养分释放速率，使其与作物生长规律更加匹配。【方法】采用溶液缩聚法配合反应挤出工艺，使柠檬酸与脲甲醛的反应前驱体羟甲基脲（MU）共聚，制备得到一种新型具有优异氮养分缓释效果的缓释肥。采用FTIR和NMR对柠檬酸改性脲甲醛缓控释肥料（CAUF）的官能团和分子结构进行表征，采用XRD表征其结晶性，通过TG和DSC表征其热稳定性和热降解行为，通过SEM观察CAUF表面形貌。测定肥料颗粒的力学性能及CAUF在静水中的氮养分释放行为，并通过盆栽试验，研究CAUF对小油菜植株生长的影响。【结果】FTIR、NMR测试结果表明，柠檬酸的末端-COOH与-NH2反应生成酰胺键，证实了羟甲基脲与尿素间的聚合反应，且两者间形成强烈的氢键作用；XRD结果表明，柠檬酸改性使得UF的结晶度显著降低；TG、DSC分析可知，CAUF的最大热解温度从304 ℃降至297 ℃，降低了热稳定性，使材料更易于降解；压缩强度测试表明，CAUF具有更优异的力学性能。处理56 d后，柠檬酸改性脲甲醛CAUF20、CAUF30、CAUF40的氮累积释放率分别为30.20%、38.84%和47.21%，相比于UF分别提升2.83、11.47和19.84个百分点，而CAUF20、CAUF30的氮初期释放率比UF分别降低1.79、1.32个百分点。小油菜盆栽生长试验结果表明，CK与相同施氮量下UF、CAUF20、CAUF30、CAUF40 5组处理得到的小油菜的鲜质量分别为1.57、1.90、2.24、3.25、3.32 g，干质量分别为0.10、0.14、0.15、0.18、0.22 g。鲜质量、干质量两项生长指标均随柠檬酸质量分数增大而增大。【结论】柠檬酸改性脲甲醛可以降低氮养分初期释放速率，显著提高中后期释放速率，促进小油菜的生长。 |
| 英文摘要: |
| 【Objective】In order to reduce the initial nutrient release rate of urea formaldehyde (UF) and to increase the mid- to late-stage nutrient release rate, citric acid (CA) was used to chemically modify urea formaldehyde to improve the UF nutrient release rate and to better match it to crop growth patterns.【Method】A new type of slow release fertilizers with excellent nitrogen nutrient retarding effect was prepared by copolymerization of citric acid and hydroxymethyl urea (MU), the reactive precursor of urea formaldehyde, using solution polycondensation with reactive extrusion process. The functional groups and molecular structure of the citric acid modified urea formaldehyde slow release fertilizer (CAUF) were characterized by FTIR and NMR, its crystallinity was characterized by XRD, its thermal stability and thermal degradation behavior were characterized by TG and DSC, and the surface morphology of CAUF were observed by SEM. The mechanical property of the fertilizer granules and the nitrogen nutrient release behavior of CAUF in still water was determined, and the effect of CAUF on the growth of rape plants was investigated by pot experiments.【Result】The FTIR and NMR results show that the terminal -COOH of citric acid reacts with -NH2 to form amide bonds, confirming the polymerization reaction between hydroxymethyl urea and urea, and the strong hydrogen bonding is formed between them; The XRD result shows that the citric acid modification makes the crystallinity of UF significantly lower; The TG and DSC analysis shows that the maximum pyrolysis temperature of CAUF decreases from 304 °C to 297 °C, which reduces the thermal stability and makes the material easier to degrade; The compression strength test shows that CAUF has better mechanical property. After 56 d of treatment, the cumulative nitrogen release rates of citric acid modified urea formaldehyde CAUF20, CAUF30 and CAUF40 are 30.20%, 38.84% and 47.21%, respectively, which are 2.83, 11.47 and 19.84 percentage points higher than UF, while the initial N release rates of CAUF20 and CAUF30 are 1.79 and 1.32 percentage points lower than UF, respectively. The results of rapes growth trials in pots show that the fresh weights of rapes obtained from five groups of treatments: CK, UF, CAUF20, CAUF30, and CAUF40 at the same nitrogen application rate are 1.57, 1.90, 2.24, 3.25, and 3.32 g, respectively, and the dry weights are 0.10, 0.14, 0.15, 0.18, and 0.22 g. Both growth indicators, fresh weight and dry weight, increase with increasing citric acid weight fraction.【Conclusion】Citric acid modified urea formaldehyde reduces the initial release rate of nitrogen nutrients, significantly increases the mid to late release rate and promotes the growth of rapes. |
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