共查询到17条相似文献，搜索用时 125 毫秒
1.
采用无机/有机复合改性粘土作制剂载体,探讨了其对阴离子型除草剂2,4-D的控制释放作用,目的在于延长2,4-D的持效期,同时减轻其污染。利用无机和有机改性的结合优势,复合改性粘土具有更强的吸附性能,能够显著延缓2,4-D在水中和土壤中的释放。分析其水中释放动力学数据得出,2,4-D释放50%所需时间(t50)长达73.8 h,远大于有机改性粘土作载体时的1 h。土壤层释放实验表明,当2,4-D载药量在20~80 mg/g之间时,复合改性粘土均能保持良好的控制释放效果。 相似文献
2.
复合改性粘土对除草剂2,4-D的控制释放作用研究 总被引：1，自引：0，他引：1
采用无机/有机复合改性粘土作制剂载体,探讨了其对阴离子型除草剂2,4-D的控制释放作用,目的在于延长2,4-D的持效期,同时减轻其污染.利用无机和有机改性的结合优势,复合改性粘土具有更强的吸附性能,能够显著延缓2,4-D在水中和土壤中的释放.分析其水中释放动力学数据得出,2,4-D释放50%所需时间(t_(50))长达73.8 h,远大于有机改性粘土作载体时的1 h.土壤层释放实验表明,当2,4-D载药量在20～80 mg/g之间时,复合改性粘土均能保持良好的控制释放效果. 相似文献
3.
首次尝试将十六烷基三甲基铵盐阳离子改性的有机膨润土(CTMAB-Bents)用作乙草胺的吸附剂和控制释放载体。结果表明,与原土(Na-Bent)相比,CTMAB-Bents对乙草胺的吸附能力提高3~5倍,且吸附能力与改性膨润土所用CTMAB量成正相关。吸附等温曲线符合Freundlich经验方程,相关系数R>0.99,吸附能力主要取决于乙草胺在水和有机膨润土间的分配作用。与Na-Bent相比,CTMAB-Bents可以显著抑制乙草胺的释放速率,对乙草胺的半数释放时间(t50)介于20CTMAB-Bent制剂的6.57 h与100CTMAB-Bent制剂的19.0 h之间,并随改性膨润土对乙草胺吸附能力的提高而延长。释放动力学曲线符合Ritger和Peppas方程,n值(0.429~0.618)接近Fickian扩散模型,说明乙草胺在有机膨润土中的释放主要受到扩散控制。 相似文献
4.
首次尝试将羧甲基壳聚糖与改性膨润土复合用作除草剂莠去津的载体,制备得到控释型颗粒剂,以延缓莠去津的释放,减少淋溶损失,提高药效及控制其污染。通过水中释放实验研究了制剂配方对莠去津释放速率的影响,并借助半经验方程探讨了其释放机理,采用土壤薄层实验考察了复合载体对降低莠去津淋溶的效果。 结果表明,采用复合载体时莠去津的半数释放时间(t 50)可达700 h 以上,比对照采用单一羧甲基壳聚糖作载体时延长了1倍以上。莠去津由颗粒剂向水相释放的过程主要受费克扩散(Fickian diffusion)控制,且经9次淋洗后莠去津的累计淋出率仅为6.0%,表明该复合载体控释制剂可显著减少莠去津对地下水的污染。 相似文献
5.
6.
二甲戊灵聚氨酯微胶囊的释放动力学 总被引：1，自引：0，他引：1
采用界面聚合法制备了二甲戊灵聚氨酯47%微囊悬浮剂,测得其平均粒径为4.75μm。将该微囊悬浮剂分别做130℃干燥2h和20℃干燥48h两个处理,将所得干样品置于二甲苯中进行释放动力学研究。结果表明,20℃干燥的样品释放更快,4h累积释放百分率已达到96.57%,130℃干燥的样品4h累积释放百分率为43.56%,10h达到了92.05%。130℃下干燥的样品前10h释放拟合曲线比较符合零级动力学方程,而20℃下干燥的样品前4h释放拟合曲线比较符合一级动力学方程。 相似文献
7.
为了对二氧化硅载药体系进行评价,以吡唑醚菌酯为模式农药,利用其与正硅酸乙酯在碱性条件下的水解缩合反应,以十六烷基三甲基溴化铵(CTAB)为模板剂,制备了吡唑醚菌酯/二氧化硅微球。通过扫描电子显微镜、Nicolet iS5傅里叶变换红外光谱及高效液相色谱等表征了微球的表面形态和化学结构,测定了其在水中的光解速率;并采用透析袋法探讨了该微球在不同pH值和不同温度下的缓释行为,通过菌丝生长速率法测定了该微球对稻瘟病菌的毒力,评价了其生物活性。结果表明:所制备的吡唑醚菌酯/二氧化硅微球外观形貌较为规整,粒径在0.998~1.428 μm之间,其最大载药量可达50.73%。该微球在碱性条件下的释药速率快于酸性条件下,且其释放均符合一级反应动力学方程,在中性条件下其释药符合Ritger-Peppas方程;与pH值相比,温度对其释药速率的影响较小。给药后第5天,所制备吡唑醚菌酯/二氧化硅微球的毒力与原药相近,给药后第9天,其毒力是原药的11.7倍,缓释效果显著。该吡唑醚菌酯/二氧化硅微球在紫外灯照射10 h后光解率为38.98%,明显低于吡唑醚菌酯原药的光解率(68.92%)。 相似文献
8.
介孔二氧化硅粒子(MSNs)可作为载体用于制备高载药量的农药缓控释剂,从而实现农药减量化使用和生态环境保护的目的。本研究采用“一锅法”制备了负载咪鲜胺的介孔二氧化硅载药粒子(prochloraz@MSNs),并对其外观形貌、载药量、释放行为、抑菌作用以及对非靶标生物的安全性进行了系统研究。结果表明：所制备的prochloraz@MSNs呈规则球形,粒径均匀,平均粒径约240 nm,载药量为40.6%,释放速率与pH值和温度相关,酸性、碱性及高温条件均有利于其中咪鲜胺的释放。与常规制剂咪鲜胺乳油相比,prochloraz@MSNs对稻瘟病菌和小麦赤霉病菌的抑制效果更好,持效期更长;对斑马鱼、蚯蚓和人体肺部BEAS-2B细胞的毒性较低。因此,prochloraz@MSNs作为一种高效、低毒、安全的农药新剂型,在植物病害的可持续治理中将具有很好的发展潜力。 相似文献
9.
介孔活性炭阿维菌素载药系统的性能研究 总被引：1，自引：1，他引：0
研究了介孔活性炭对阿维菌素的载药特性,以判断其作为阿维菌素载体的可能性。以扫描电子显微镜、比表面积分析仪和粒度分析仪对其进行了物理性状表征。将其负载阿维菌素的能力与常规农药载体进行比较,并进一步分析和评价了该载药系统的吸附动力学特性、缓-控释性能和抗紫外光降解能力。结果表明:供试活性炭载体为不规则球形颗粒状介孔材料,平均粒径为814 nm,比表面积为1 719.25 cm2/g,孔容积为0.043 cm3/g,孔径为4.80 nm。吸收动力学数据符合伪二级动力学模型,对阿维菌素的载药量为220.6 mg/g,显著高于其他常规农药载体,呈现了优良的吸附性能;载药系统的释药时间从90 h延长到672 h以上,表现出了良好的缓释效果;紫外光照射72 h后,阿维菌素原药的分解率为77%,而有活性炭载体保护的阿维菌素的分解率为30% ,表明该载药系统有效地减缓了阿维菌素的光降解速率。研究表明,以介孔活性炭作为阿维菌素载体,可显著改善药物的缓-控释特性以及分散性和光稳定性。 相似文献
10.
探索了以酚醛环氧树脂-二元胺聚合物为壁材制备高效氯氟氰菊酯微囊(CS)的可行性,明确了酚醛环氧树脂用量及乳化剪切转速等因素对微囊基础物化特性以及药剂释放性能和应用效果的影响。利用油溶性单体酚醛环氧树脂与水溶性单体丙二胺,在油-水界面上发生聚合反应形成不溶于水的聚合物,制备得到高效氯氟氰菊酯微囊。通过光学显微镜和扫描电子显微镜观察其形貌;利用红外光谱仪分析囊壁结构;采用气相色谱法分析微囊的载药量、包封率和释放性能;经粒度分析仪测定平均粒径和粒度分布;最后采用浸叶法测定了该载药微囊的杀虫活性。结果表明:所得高效氯氟氰菊酯微囊为规则的球形,囊壁表面光滑无孔洞且伴有少量褶皱。随酚醛环氧树脂用量增加,微囊平均粒径增大,载药量下降,释放速率降低,而包封率变化不大。随乳化剪切转速增加,平均粒径下降,释放速率加快。采用优化条件制备所得微囊的平均粒径为21.33 μm,包封率为91.04%,载药量为43.97%。其释放动力学表现为:0~15 min内为快速释放阶段,累计释放量达到78.01%;15~240 min为缓慢释放阶段,在240 min时累积释放量达97.04%。4种不同粒径(2.78、5.19、11.86和23.15 μm)高效氯氟氰菊酯微囊和同剂量高效氯氟氰菊酯乳油对小地老虎幼虫的毒力测定结果表明:随着微囊粒径的减小,其毒力逐渐增大(LC50值分别为16.44、23.33、29.36和37.57 mg/L),但不同粒径微囊处理组毒力均略低于乳油(LC50值为10.41 mg/L)。研究表明,可采用酚醛环氧树脂-二元胺聚合物为壁材制备高效氯氟氰菊酯微囊,速效性好且活性易调控,在农药微囊剂制备中具有很好的应用前景。 相似文献
11.
M Villafranca‐Snchez E Gonzlez‐Pradas M Fernndez‐Prez F Martinez‐Lpez F Flores‐Cspedes M
D Urea‐Amate 《Pest management science》2000,56(9):749-756
The herbicide isoproturon [3‐(4‐isopropylphenyl)‐1,1‐dimethylurea] was incorporated in alginate‐based granules to obtain controlled‐release (CR) properties. The basic formulation (sodium alginate (1.87%)–isoproturon (0.67%) in water) was modified by addition of different sorbents. The effect on isoproturon release rate, modified by the incorporation of natural and acid‐treated bentonite in alginate formulation, was studied by immersion of the granules in water while shaking. The release of isoproturon was diffusion‐controlled. The time taken for 50% of the active ingredient to be released into water, T50, was longer for those formulations containing added bentonite (5.98 and 7.43 days, for natural and acid‐treated (1 M H2SO4) bentonite, respectively) than for the preparation without bentonite (3.78 days). The mobilities of non‐formulated technical grade (98%) and formulated isoproturon were compared using soil columns. The use of alginate‐based CR formulations containing bentonite reduced isoproturon movement compared with the technical product. Sorption capacity of the soil for isoproturon was measured using batch experiments (0.29 litre kg−1) and the results obtained here in agreement with those obtained under dynamic conditions. © 2000 Society of Chemical Industry 相似文献
12.
Controlled-release herbicide formulations have been shown to decrease the leaching potential of several herbicides under laboratory and field conditions. The utility and efficacy of these formulations may be improved by combining several herbicides and a fertilizer source in a single formulation. The objective of these studies was to develop granular alginate formulations that were composed of a combination of the herbicides atrazine and alachlor with the slow-release nitrogen source oxamide (ethanediamide). Controlled release of the herbicides was obtained by addition of selected minerals, including calcium bentonite, fine-grind bentonite, montmorillonite K10, kaolinite and iron (III) oxide. A formulation without clay was used as a comparison. The formulations tested had herbicide active ingredient contents ranging from ∽0·02 to 0·54% and a nitrogen content of 21%. Release of the herbicides was studied by equilibrating the formulations with deionized water on a rotary shaker at 200 rev min-1 and sampling at regular time intervals up to 104 hours. The minerals used in the different formulations influenced the herbicide active ingredient composition, as well as the release properties of the individual formulations. The atrazine content of the formulations decreased in the order calcium bentonite>fine-grind bentonite>kaolinite>montmorillonite=iron oxide>no clay. For alachlor the content decreased in the order of calcium bentonite>fine-grind bentonite>montmorillonite>iron oxide>kaolinite>no clay. Controlled release of atrazine (i.e. reduction in release rate) varied in the order calcium bentonite>iron oxide>montmorillonite>fine-grind bentonite= kaolinite>no clay, and for alachlor fine-grind bentonite>calcium bentonite>montmorillonite>no clay=kaolinite=iron oxide. A certain percentage of the applied active ingredient of both alachlor and atrazine was not recovered. From 5 to 27% of the active ingredient was not released, with the greatest retention by the bentonite formulations. Release of nitrogen was not strongly influenced by mineral type, although a trend indicated greater release with formulations containing kaolinite. © 1998 SCI 相似文献
13.
Controlled-release formulations of 14C-labelled thiobencarb herbicide were prepared in calcium alginate using kaolin as an inexpensive filler. The rates of release of the herbicide from these and from a commercial granular formulation were studied in static distilled water contained in open and closed vessels. The rate of release of the herbicide was much higher from the commercial formulation than from the controlled-release formulations. Increasing the proportion of kaolin to calcium alginate in controlled-release formulations reduced the rate of release of the herbicide. There was a significant loss of thiobencarb-related radioactivity from the water solution when the vessels containing the solutions were left uncovered and exposed to light. The loss of the herbicide seemed to be due to degradation and evaporation. 相似文献
14.
E Gonzlez-Pradas M Fernndez-Prez M Villafranca-Snchez F Martínez-Lpez F Flores-Cspedes 《Pest management science》1999,55(5):546-552
In order to prepare a formulation to be used for controlled release, imidacloprid was incorporated into alginate granules by using calcium chloride as gellant. The formulation prepared (alginate–imidacloprid–water) was modified by the addition of different sorbents. The effects on release rate of the addition of natural bentonite desiccated at 105 °C, untreated, acid-treated with sulfuric acid solutions over a concentration range between 0.5 mol dm−3 and 2.5 mol dm−3, and a commercial humic acid, were studied by immersion of the granules in water under static conditions. The time taken for 50% of the active ingredient to be released into water, (T50), was calculated from the data obtained. On the other hand, the sorption–desorption processes of imidacloprid from a 0.01 M aqueous calcium chloride solution at 25 °C, by natural, acid-treated bentonite samples, and humic acid, have been studied by using batch experiments in order to evaluate the potential of these materials for their application in controlled-release formulations of pesticides. The experimental data have been fitted to the Freundlich equation in order to calculate the adsorption capacities (Kf). Kf values ranged from 1.76 mg kg−1 for the untreated bentonite up to 126.9 mg kg−1 for the humic acid. A correlation study was performed with T50, the surface area (S) and the Freundlich parameter (Kf) of the bentonite samples in order to know the factors that affect release rate of imidacloprid from bentonite granules. A linear correlation of the T50 values and both S and Kf parameters was observed. © 1999 Society of Chemical Industry 相似文献
15.
Yasser El-Nahhal Shlomo Nir Tamara Polubesova Leon Margulies Baruch Rubin 《Pest management science》1999,55(8):857-864
The use of commercially available formulations of metolachlor has resulted in its leaching and migration to water sources. Formulations of metolachlor designed to reduce its leaching in soil have been prepared by adding the herbicide dissolved in an organic solvent or in water to organo-clay complexes. Best formulations were made when the organo-clay complex was formed by adsorbing the monovalent organic cations benzyltrimethylammonium (BTMA) or benzyltriethylammonium (BTEA) onto sodium montmorillonite (Mont) at 0.5 or 0.8 mole kg−1 clay. Adsorption of metolachlor to organo-clays followed the sequence Mont-BTMA 0.5 > Mont-BTMA 0.8 > Mont-BTEA 0.8 > Mont-BTEA 0.5 > Mont. Fourier transform infrared (FTIR) analysis demonstrated the occurrence of shifts of several peaks of adsorbed metolachlor relative to the free herbicide, indicating the existence of strong interactions between metolachlor molecules and the organo-clay surface. Leaching studies employing organo-clay and commercial formulations were carried out under greenhouse and field conditions. Metolachlor applied as organo-clay formulations leached less than the commercial formulation. Organo-clay formulations prepared by adding the herbicide as a water solution showed less leaching in the soil profile than those made by using organic solvent. Under greenhouse conditions, the herbicidal activity of organo-clay formulations was similar to that of the commercial one. Under field conditions, leaching from Mont-BTMA 0.5-metolachlor was less than that from the commercial formulation, demonstrating the environmental and agricultural advantages of the organo-clay formulations of metolachlor. © 1999 Society of Chemical Industry 相似文献
16.
Claudia C. Medugno Jos M. G. Ferraz Aline de H. N. Maia Cludio C. L. Freitas 《Pest management science》1997,51(2):153-156
The influence of different carriers on the physical and biological stability of Baculovirus anticarsia wettable powder formulations was studied. The formulations were obtained by mixing the purified polyhedra of B. anticarsia with a carrier and drying the suspension in a bench spray dryer. Bioassays with Anticarsia gemmatalis Hübner showed that activity was maintained with the amorphous silica, attapulgite and kaolinite after a year of storage. In the presence of bentonite, activity declined 50% in the same period. All formulations, except kaolinite, maintained the physical parameters required of a good wettable powder. Kaolinite formulation showed reduction in wettability and particle agglomeration in storage. © 1997 SCI 相似文献
17.
R.E. Wilkinson 《Pesticide biochemistry and physiology》1981,16(1):63-71
Height and fresh weight of sorghum (Sorghum bicolor L. var GA 522 DR) grown in sand were reduced by metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide) (0, 0.125, 0.25, 0.5, or 1 ppmw) applied preemergence. Significantly different responses were obtained from plants grown at two light intensities (270 and 27 μein/m2/sec). When grown in nutrient solution containing 0, 0.0156, 0.0625, 0.25, 1, 16, or 64 ppmw metolachlor, shoot and root lengths were inhibited by metolachlor; fresh and dry weights of shoot, root, and total plant decreased as metolachlor concentration increased. Carotene content (micrograms per gram fresh weight) in sorghum leaves was decreased by metolachlor. Specific activity of carotene synthesized from [2-14C] mevalonic acid by carrot (Daucus carota L.) disks was reduced 50% by 10?5 and 10?4M metolachlor. Thus, terpenoid biosynthesis is influenced by metolachlor. Gibberellins are terminal products of plant terpenoid biosynthesis, and GA3 reverses metolachlor inhibition of growth at specific ratios of GA3 and metolachlor but not at other concentrations. Thus, one effect of metolachlor on plants may be an inhibition of GA synthesis that results in shoot and root growth reductions as metolachlor concentration increases. Other growth responses of plants to metolachlor are unexplained. 相似文献