亲水凝胶包覆型丙酯草醚的制备、性能及其土壤行为规律的示踪法研究

发布时间：2018-04-18 15:20

本文选题：环境友好型农药 + 污染削减　；参考：《浙江大学》2014年博士论文

【摘要】：农药是保证农作物增产增收的重要生产资料和技术手段,化学农药的大量使用在带来巨大经济效益的同时也会造成不容忽视的环境污染问题。研发高效且环境友好的新型农药一直是倍受科技界关注的热点问题。丙酯草醚是我国具有自主知识产权的油菜田除草剂,可有效防控油菜田的杂草危害,研究表明丙酯草醚的在土壤中形成的结合残留积累到一定量后会对后茬作物水稻产生药害。如何在保持其高效的同时并兼顾环境利益是目前亟待解决的一个科学问题。将农药与高分子化合物通过包被、键合等方式可以实现农药的可控释放,以提高农药的利用率并降低环境风险。本论文基于农药缓释理论,围绕削减丙酯草醚残留、降低其环境风险这一目标,创制了一种环境低残留的“亲水凝胶包覆型丙酯草醚”新制剂(HGC-ZJ0273)。本论文根据目前缓释农药中常用的淀粉改性水凝胶为研究内容,采用10MeV辐照技术引发活化的木薯淀粉丙烯酰胺为单体进行10MeV电子束辐照引发自由基共聚合,并通过进一步的碱性水解制备吸水材料。实验采用FTIR技术、13C-NMR技术和SEM技术对原料和反应产物的化学与物理结构进行了表征,证明木薯淀粉和丙烯酰胺在溶液状态下可以由10MeV引发进行共辐照接枝共聚,并且接枝共聚反应主要发生在淀粉脱水葡萄糖单元环的C6上。聚合产物经纯化后由于分子间静电排斥的作用具有大量的孔隙通道,为后续实验中水分子的进入和农药分子的溶出提供了通道。获得最佳吸水性能的凝胶的反应条件为：AM/AGU=4.5mol mol-1, D=8kGy,交联剂MB A/AM=4mmol mol-1,聚合产物经5%NaOH水溶液水解120min可以获得最佳的吸水性能,上述条件下凝胶在去离子水和0.9%NaCl水溶液中的吸收能力分别为1452g g。和83g g-1。根据上述亲水凝胶制备的方法学研究,在此基础上,制备了一种具有良好释放性能的“亲水凝胶包覆丙酯草醚”(HGC-ZJ0273)新制剂。实验采用K2S208为引发剂,将丙酯草醚的二甲苯溶液采用合适的表面活性剂以乳化法引入淀粉-丙烯酰胺/丙烯酸钠接枝共聚体系,通过接枝共聚将丙酯草醚包覆在淀粉接枝亲水凝胶内。采用SEM技术对HGC-ZJ0273的表面形态进行表征,发现其内部分布着大量孔隙结构,为HGC-ZJ0273中水分子进出和药物分子的释放提供了通道,丙酯草醚以颗粒状均匀分布于凝胶内部和孔隙表面。经进一步HPLC-LSC技术分析,表明丙酯草醚活性分子在聚合过程中未发生结构改变。对HGC-ZJ0273在去离子水、缓冲溶液以及土壤浸出溶液中的释放动态进行了测试,释放曲线符合Rigter-Peppas释放动力学模型,在释放36h后可以达到释放平衡,丙酯草醚在三种释放介质中的释放量从大到小依次为：土壤浸提液去离子水缓冲溶液,并且随表面活性剂用量的增加,释放速率和释放总量都会上升。采用盆栽法实验研究了HGC-ZJ0273对敏感植物高粱幼苗的生物抑制活性,结果显示在较低的施药浓度下即具有除草活性(对高粱幼苗产生明显药害,半抑制浓度为67.82μg g-1土壤)。本论文综合运用同位素示踪和现代仪器分析技术,从质量平衡角度,系统研究了14C标记亲水凝胶包覆丙酯草醚在好氧土壤环境中的消减及残留的不同赋存形态(可提态残留、结合残留和矿化)的转化规律,并与丙酯草醚原药在土壤中的残留规律进行了对比。HGC-ZJ0273母体在S1-S3中的半减期分别为21.49d、6.45d和10.75d,消减速率明显高于常用丙酯草醚在相应土壤中的消减速率,且降解速率和残留形态受土壤类型的影响。 HGC-ZJ0273在土壤中可以通过开环矿化彻底脱毒,且矿化量与土壤类型有关。在有机质含量高的中性土壤S2和碱性土壤S3中矿化量较大,分别为41.2%和29.4%,而在酸性土S1中则不易矿化(1.0%)。丙酯草醚原药在相应的3种土壤中的矿化率分别为24.1%、9.8%和0.3%。实验证实,与常用丙酯草醚相比,凝胶包覆处理可显著增加丙酯草醚在中性和碱性土壤中的开环矿化量(分别增加了17.1%和19.6%),即可显著削减丙酯草醚在土壤中的残留总量。 HGC-ZJ0273在中性土壤S2中主要通过减少结合残留的形成来削减总残留量,而二者的可提态残留分别为13.8%和12.9%差异不显著,至培养结束时(80d),前者的结合残留为56.1%,后者仅为43.7%,ER+BR的总量平均削减了13.3%；在碱性土壤S3中HGC-ZJ0273呈现与中性土壤不同的规律,主要通过削减可提态残留来降低总残留量,前者的可提态残留为60.6%,而后者降至22.7%,结合残留则出现升高,二者在S3中的结合残留分别为26.7%和40.0%,ER+BR的总量平均削减了24.6%。在酸性土壤中HGC-ZJ0273和常用丙酯草醚的可提态残留分别为80.6%和82.9%,结合残留分别为15.9%和12.2%,ER+BR的总量分别为96.5%和95.1%,差异不显著。基于HGC-ZJ0273以及常用丙酯草醚在三种土壤中ER和BR残留情况,凝胶包覆处理可显著降低丙酯草醚在中性土壤S2和碱性土壤S3中的残留总量,究其原因,中性土壤的有机质含量相对较高,营养源丰富,微生物活性较高,凝胶的加入以及凝胶内部的农药分子又为微生物提供了外源碳源,进一步促进了把丙酯草醚的土壤生物降解。在碱性土壤S3中,HGC-ZJ0273的加入也为土壤微生物提供了营养源,促进微生物将丙酯草醚降解为各种产物,进而显著增加了丙酯草醚的矿化量。但与原药相比其结合残留相对较高,这可能是亲水凝胶分子链存在大量-NH2等基团易与丙酯草醚的酸性降解产物通过离子化作用或分子间氢键作用产生不可被常规方法提取的结合态形式。尽管凝胶包覆处理会导致丙酯草醚在S3中的结合残留升高,但仍远小于欧盟关于登记授权的新农药有关结合残留的限值(70%)。凝胶包覆处理并未对酸性土壤S1的矿化及残留规律产生影响,且残留形式主要以可提态残留形式存在,这主要是因为HGC-ZJ0273在酸性环境介质中不易释放,加之酸性土壤微生物活性低,从而导致了丙酯草醚在酸性土壤中的残留居高不下。这与丙酯草醚原药不适用于酸性土壤类似。本论文研究揭示,HGC-ZJ0273可以削减丙酯草醚在土壤中的残留,较好的兼顾了高效与环境友好这两种独特优势,这反映出HGC-ZJ0273具有较好的应用前景。
[Abstract]:A new type of pesticide formulation ( HGC - ZJ0273 ) has been developed to reduce the environmental risks .

The chemical and physical properties of cassava starch and acrylamide were studied by FTIR , 13C - NMR and SEM techniques . The results showed that cassava starch and acrylamide could be co - irradiated by 10 MeV electron beam irradiation . The results showed that cassava starch and acrylamide could be induced by 10 MeV irradiation . The results showed that the optimum conditions for the gel were : AM / AGU = 4.5 mol - 1 , D = 8kGy , cross - linking agent MB A / AM = 4mmol mol - 1 . The absorption capacity of the gel in deionized water and 0.9 % NaCl solution was 1452g / g and 83g g - 1 respectively .

A new preparation of " hydrophilic gel - coated propyl ester grass ether " ( HGC - ZJ0273 ) with good release properties was prepared on the basis of the methodology of hydrophilic gel preparation . The surface morphology of HGC - ZJ0273 was characterized by using K2S208 as initiator . The surface morphology of HGC - ZJ0273 was characterized by grafting copolymerization .

The release kinetics of HGC - ZJ0273 in deionized water , buffer solution and soil leaching solution were tested .

In this paper , using isotope tracing and modern instrument analysis technique , the transformation law of 14C - labeled hydrophilic gel - coated propyl ester - butyl ether in aerobic soil environment and the residual laws of residue were studied from the viewpoint of mass balance . The half - reduction period of HGC - ZJ0273 parent in S1 - S3 was 21.49d , 6.45d and 10.75d , respectively , and the decrease rate was obviously higher than that of common propyl ester grass ethers in the corresponding soil , and the degradation rate and residual form were affected by soil type .

HGC - ZJ0273 can be completely detoxicate through open - loop mineralization in the soil , and the amount of mineralization is related to the soil type . In the neutral soil S2 and alkaline soil S3 with high organic matter content , the mineralization rate is 41.2 % and 29 . 4 % , respectively , while in the acid soil S1 , the mineralization rates are 24.1 % , 9.8 % and 0.3 % , respectively .

HGC - ZJ0273 mainly reduces the total residue by reducing the formation of binding residues in the neutral soil S2 , while the residual amounts of the two can be 13.8 % and 12.9 % respectively , and the residual amount of the former is 56.1 % , the latter is only 43.7 % , and the total amount of ER + BR is reduced by 13.3 % .
In alkaline soil S3 , HGC - ZJ0273 showed a different regularity from neutral soil . The residual amount of the former was reduced by 60.6 % , while the latter decreased to 22 . 7 % . The residual amount of ER + BR decreased by 24 . 6 % . In acidic soil HGC - ZJ0273 and commonly used propyl ester grass ethers were 80.6 % and 82.9 % , respectively , and the total amount of ER + BR was 96.5 % and 95.1 % , respectively , and the difference was not significant .

In alkaline soil S3 , the addition of HGC - ZJ0273 also provides a source of nutrients for soil microorganisms .

The results show that HGC - ZJ0273 can reduce the residue of propyl ester grass in soil , and the two unique advantages of high efficiency and environment friendship are well balanced , which reflects the good prospect of HGC - ZJ0273 .

【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：X592

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