Synthesis,Structural,Spectroscopic Characterization and Biological Properties of the Zn(Ⅱ),Cu(Ⅱ),Ni(Ⅱ),Co(Ⅱ),and Mn(Ⅱ)Complexes With the Widely Used Herbicide 2,4-Dichlorophenoxyacetic Acid

2,4-Dichlorophenoxyacetic acid(2,4-D)is a board-leaf selective herbicide and globally used in agricultural activities.Complexation mode,spectroscopic investigations and biological properties of complexes formed between 2,4-D(C_(6)H_(3)Cl_(2)OCH_(2)·COOH;HL)with Zn(Ⅱ),Cu(Ⅱ),Ni(Ⅱ),Co(Ⅱ),and Mn(Ⅱ)metal ions were investigated.To characterize the binding mode between 2,4-D and the metal ions,many physicochemical approaches were employed.The complexes obtained are characterized quantitatively and qualitatively by using micro elemental analysis,FTIR spectroscopy,UV-Vis spectroscopy,1H-NMR,and magnetic susceptibility measurements.Results of these approaches suggested that the gross formula of the complexes obtained with the metal ions were[ZnL_(2)](2H_(2)O(1),[CuL_(2)(H_(2)O)_(2)](2),[NiL_(2)](3H_(2)O(3),[CoL_(2)(H_(2)O)_(2)](4),and[MnL_(2)(H_(2)O)_(2)](5).In all complexes,two L-anion were coordinated the metal ion by their bidentate carboxylate groups.From the spectral study,all the complexes obtained as monomeric structure and the metals center moieties are six-coordinated with octahedral geometry except Ni(Ⅱ)and Zn(Ⅱ)complexes which existed as a tetrahedral and square pyramidal geometry respectively.The complexes were screened in vitro against several microbes(fungi and bacteria)using Kirby-Bauer disc diffusion method,and data has demonstrated that complex 3 showed excellent antifungal activity.

Degradation of 2,4-dichlorophenoxyacetic acid in water by ozonehydrogen peroxide process

This study reports an investigation into the degradation of 2,4-dichlorophenoxyacetic acid in bubble contactor column by O2/H2O2 process, which is widely used as a principal advanced oxidation process. The degradation of 2,4-dichlorophenoxyacetic acid was studied under different H202/O3 molar ratio and pH value. Meanwhile, TOC removal was investigated both in distilled water and tap water. The influences of ozone transfer and consumed hydrogen peroxide were also discussed. The degradation products and oxidation intermediates were identified by GC-MS and LC-MS. A possible reaction mechanism was thus proposed.

Selective removal of 2,4-dichlorophenoxyacetic acid from water by molecularly-imprinted amino-functionalized silica gel sorbent

A molecularly-imprinted amino-functionalized sorbent for selective removal of 2,4-dichlorophenoxyacetic acid （2,4-D） was prepared by a surface imprinting technique in combination with a sol-gel process. The 2,4-D-imprinted amino-functionalized silica sorbent was characterized by FT-IR, nitrogen adsorption and static adsorption experiments. The selectivity of the sorbent was investigated by a batch competitive binding experiment using an aqueous 2,4-D and 2,4-dichlorophenol （2,4-DCP） mixture or using an aqueous 2,4-D and 2,4- dichlorophenylacetic acid （DPAC） mixture. The largest selectivity coefficient for 2,4-D in the presence of 2,4-DCP was found to be over 18, the largest relative selectivity coefficient between 2,4-D and 2,4-DCP over 9. The static uptake capacity and selectivity coefficient of the 2,4-D-imprinted functionalized sorbent are higher than those of the non-imprinted sorbent. The imprinted functionalized silica gel sorbent offered a fast kinetics for the extraction/stripping of 2,4-D, 73% of binding capacity （200 mg/L 2,4-D onto 20 mg of imprinted sorbent） was obtained within 5 min and the adsorbed 2,4-D can be easily stripped by the mixture solution of ethanol and 6 mol/L HC1 （V：V =1：1）. In a test of five extraction/stripping cycles, the adsorption capacity of the sorbent was all above 93% of that of the fresh sorbent. Experimental result showed the potential of molecularly-imprinted amino-functionalized sorbent for selective removal of 2,4-D.

Photochemical degradation of typical halogenated herbicide 2,4-D in drinking water with UV/H_(2)O_(2)/micro-aeration

UV/H2O2/micro-aeration is a newly developed process based on UV/H2O2. Halogenated pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) photochemical degradation in aqueous solution was studied under various solution conditions. The UV intensity,initial 2,4-D concentrations and solution temperature varied from 183.6 to 1048.7 μW·cm-2,from 59.2 to 300.0 μg·L-1 and from 15 to 30℃,respectively. The concentration of hydrogen peroxide (H2O2) and pH ranged from 0 to 50 mg·L-1 and 5 to 9,and different water quality solutions (tap water,distilled water and deionized water) were examined in this study. With initial concentration of about 100 μg·L-1,more than 95.6% of 2,4-D can be removed in 90 min at intensity of UV radiation of 843.9 μW·cm-2,H2O2 dosage of 20 mg·L-1,pH 7 and room temperature. The removal efficiency of 2,4-D by UV/H2O2/micro-aeration process is better than UV/H2O2 process. The photodecomposition of 2,4-D in aqueous solution follows pseudo-first-order kinetics. 2,4-D is greatly affected by UV irradation intensity,H2O2 dosage,initial 2,4-D concentration and water quality solutions,but it appears to be slightly influenced by pH and temperature. There is a linear relationship between rate constant k and UV intensity and initial H2O2 concentration,which indicates that higher removal capacity can be achieved by the improvement of these factors. Finally,a preliminary cost analysis reveals that UV/H2O2/micro-aeration process is more cost-effective than the UV/H2O2 process in the removal of 2,4-D from drinking water.

Removal of herbicide 2,4-D using constructed wetlands at pilot scale

Herbicide 2,4-D is one of the most widely used in the world.In this way,its presence on different bodies of water has been reported.In this paper the efficiency of horizontal-subsurface flow constructedwetlands for 2,4-D removal in aqueous solutions was assessed.Wetlands were constructed using fiberglass,and grown with Phragmites australis.The influent consisted of synthetic wastewater under different 2,4-D and glucose initial concentrations.Results indicated that,under the evaluated experimental conditions,2,4-D extent of removal was between 71.0 and 99.0%.In general,it can be noted that an increase in the herbicide concentration reduces the removal efficiency,probably due to a toxic effect on the biological component.On the other hand,the influent dissolved organic carbon(DOC)initial concentration had a significant effect on the removal of both,the herbicide and the organic matter content in the system,demonstrating that this parameter has a significant effect on this kind of biological methods for water treatment.Finally,it can be concluded that constructed wetlands are a viable alternative for the treatment of wastewater contaminated with the herbicide 2,4-D.

除草剂2,4-D在胡敏酸上的吸附

报道了除草剂 2 ,4 D在胡敏酸上的吸附 .结果表明 :2 ,4 D在胡敏酸上的吸附符合非线形的Freundlich吸附等温线 .胡敏酸的粒径、含量 ,以及环境温度对 2 ,4 D的吸附均有影响 .2 ,4 D在胡敏酸上的吸附量随胡敏酸的粒径变小以及其含量的增加而增大 。

臭氧超声波联合降解除草剂2,4-D(Ⅱ) 降解路径的探讨

利用臭氧超声波联合工艺对苯氧羧酸类除草剂 2 ,4 D进行降解研究 ,在前文探讨臭氧超声波之间协同效应的基础上 ,确定其中间产物种类主要有 2 ,4 二氯苯酚、苯醌、氢醌以及小分子酸如顺丁烯二酸、草酸、甲酸、乙酸等 .在不同实验条件下 ,分别对反应溶液里的主要中间产物和离子浓度变化进行分析 ,研究 2 ,4 D在臭氧超声波联合作用下的反应路径 ,并初步讨论其降解机理 .

O_3与O_3/H_2O_2两个体系降解除草剂2,4-D反应特性研究

分别采用O3、O3/H2O2体系降解苯氧羧酸类除草剂2,4-D,探讨了降解过程中反应温度、pH值、O3混合气流量、有机物初始浓度等操作条件的变化对降解动力学的影响。结果发现,温度和pH值的影响较大,O3流量影响最小,温度升高、pH值增大、臭氧流量增加、2,4-D初始浓度降低均有助于降解速率的提高。O3/H2O2体系中,H2O2能促进O3分解产生大量自由基,导致2,4-D反应活化能降低。和O3相比,O3/H2O2体系降解效果好,降解时间短,反应条件温和,操作费用低,是很有发展前景的高级氧化技术。

固相萃取富集高效液相色谱法测定苯氧乙酸和2,4-二氯苯氧乙酸

建立了以固相萃取技术进行富集 ,高效液相色谱法进行分离和检测苯氧乙酸和 2 ,4 二氯苯氧乙酸的方法。环境水中的苯氧乙酸和 2 ,4 二氯苯氧乙酸用Sep PakC18Cartridge进行固相萃取。液相色谱的条件是 :Shim PackCLCODS柱为分析柱 ;甲醇 水 (9∶1,V/V)为流动相 ;流速为 1mL/min ;在UV 2 75nm波长下进行检测。

2,4-二氯苯氧乙酸的研究进展

2,4-二氯苯氧乙酸经常作为除草剂和植物生长调节剂使用,在农林业中发挥了重大作用,尤其在水果(如柑橘)保鲜中应用广泛,但其毒性问题也受到广泛关注,因此了解2,4-D的生理作用、在生物及环境中的代谢降解、残留毒性和提取鉴定等的研究进展很有必要.

2,4-二氯苯氧乙酸合成方法的正交试验研究

改进2,4-二氯苯氧乙酸(2,4-D)传统的合成工艺。主要反应不是采取先氯化的方法,而是先以苯酚和氯乙酸缩合后,再用次氯酸钠进行氯化的后氯化法,进而用正交试验,确定了新方法的最佳工艺条件:投料比为苯氧乙酸/g∶冰醋酸/mL=1∶9,次氯酸钠投入量为18mL(滴加),反应温度为冰水浴中进行,酸化至pH<1条件下,产品收率最高。测定了产品的mp IR和NMR,均与文献值相符。

2,4-二氯苯氧乙酸臭氧化过程中过氧化氢的生成

The method of degradation of 2,4-dichlorophenoxyacetic acid by ozonation in a cylindrical bubbling tower reactor was proposed.It was revealed that hydrogen peroxide was detected during the ozonation of 2,4-dichlorophenoxyacetic acid.Hydrogen peroxide is useful to decompose ozone in aqueous solution to form hydroxyl radicals.Therefore,hydrogen peroxide has an effect on the 2,4-dichlorophenoxyacetic acid degradation.In order to understand the formation of hydrogen peroxide during ozonation of 2,4-dichlorophenoxyacetic acid,the effect of various experimental parameters on the concentration of hydrogen peroxide was investigated.The experimental results showed that the formation of hydrogen peroxide depended on 2,4-dichlorophenoxyacetic acid in aqueous solution.The yield of hydrogen peroxide produced by ozone decomposition was relatively small and could be neglected.The reaction of H2O2 decay simultaneously took place in reaction solution with the reaction of H2O2 formation.The change of concentration of hydrogen peroxide in aqueous solution indicated an accumulation phase and a consumption phase.As the pH level decreased,the formation rate of hydrogen peroxide also decreased.On the other hand,with the increase of pH level,the decay rate of hydrogen peroxide increased.It is shown that hydrogen peroxide was mainly formed by the direct oxidation of ozone molecule with 2,4-dichlorophenoxyacetic acid.The decay of hydrogen peroxide was induced by the excess hydroxyl radical in aqueous solution.

Insight into the mode of action of 2,4-dichlorophenoxyacetic acid(2,4-D) as an herbicide

2,4-Dichlorophenoxyacetic acid （2,4-D） was the first synthetic herbicide to be commercially developed and has commonly been used as a broadleaf herbicide for over 60 years. It is a selective herbicide that kills dicots without affecting monocots and mimics natural auxin at the molecular level. Physiological responses of dicots sensitive to auxinic herbicides include abnormal growth, senescence,and plant death. The identification of auxin receptors, auxin transport carriers, transcription factors response to auxin, and cross-talk among phytohormones have shed light on the molecular action mode of 2,4-D as a herbicide. Here, the molecular action mode of 2,4-D is highlighted according to the latest findings, emphasizing the physiological process, perception, and signal transduction under herbicide treatment.

高效液相色谱测定环境水中2,4-二氯苯氧乙酸的方法研究

建立了以高效液相色谱法进行分离和检测环境水中2,4-二氯苯氧乙酸的方法。环境水中的2,4-二氯苯氧乙酸用SPE C18小柱进行固相萃取。液相色谱的条件是:色谱柱:SPE C18 150mm×4.6mm;流动相:甲醇∶水(9∶1,V/V);流速:3mL.min-1;柱温:40℃;检测器:UV282nm;进样量10μL。回收率>98%,最低检测限为0.01mg·L-1。本法具有良好的灵敏度和重现性。

A pulsed switching peroxi-coagulation process to control hydroxyl radical production and to enhance 2,4-Dichlorophenoxyacetic acid degradation

The aim of this study was to develop a new pulsed switching peroxi-coagulation system to control hydroxyl radical(∙OH)production and to enhance 2,4-Dichlorophenoxyacetic acid(2,4-D)degradation.The system was constructed with a sacrifice iron anode,a Pt anode,and a gas diffusion cathode.Production of H_(2)O_(2) and Fe^(2+)was controlled separately by time delayers with different pulsed switching frequencies.Under current densities of 5.0 mA/cm^(2)(H_(2)O_(2))and 0.5 mA/cm^(2)(Fe^(2+)),the∙OH production was optimized with the pulsed switching frequency of 1.0 s(H_(2)O_(2)):0.3 s(Fe^(2+))and the ratio of H_(2)O_(2) to Fe^(2+)molar concentrations of 6.6.Under the optimal condition,2,4-D with an initial concentration of 500 mg/L was completely removed in the system within 240 min.The energy consumption for the 2,4-D removal in the system was much lower than that in the electro-Fenton process(686 vs.13610 kWh/kg TOC).The iron consumption in the system was~20 times as low as that in the peroxi-coagulation process(19620 vs.3940400 mg/L)within 240 min.The system should be a promising peroxi-coagulation method for organic pollutants removal in wastewater.

Effects of humic acid fractions with different polarities on photodegradation of 2,4-D in aqueous environments

Four fractions(A,B,C,and D)of humic acids(HAs)were separated based on the polarity from weak to strong.UV-vis absorption and Fourier transform infrared spectroscopy(FTIR)analysis show that the fractions C and Dpossessedmore aromatic C5C content.The influences of HAs and their fractions on the photolysis were investigated by the photodegradation of 2,4-D solutions under simulated solar light irradiation.The degradation rate of 2,4-D was found to decrease in the presence of bulk HAs or their fractions especially at high HAs concentration.The fractions of strong polarity C and D retarded the degradation rate more than the fractions of weak polarity A and B.This could be attributed to the different absorption intensity of the four HAs fractions in the order of D≥C>A>B,and the stronger π-π electron donor-acceptor interactions between the strong polar fractions and 2,4-D.

液相色谱-串联质谱法测定蔬菜中20种酸性除草剂残留

采用改良的QuEChERS法,结合液相色谱-串联质谱法(LC-MS/MS),建立了蔬菜中2,4-滴、二氯吡啶酸、精吡氟禾草灵等20种酸性除草剂的残留分析方法。样品用0.5%甲酸乙腈提取,以900 mg MgSO4+50 mg石墨化炭黑(GCB)作为基质提取液的净化剂。实验结果表明,20种酸性除草剂在一定范围内线性关系良好,其相关系数(r2)在0.9939~0.9998之间。方法的平均回收率和相对标准偏差(RSD,n=6)分别为70.3%~107%和0.2%~8.3%。该方法快速、灵敏,适用于各种蔬菜基质中酸性除草剂的残留分析。

除草剂2,4-D胁迫对土壤微生物的影响研究

高浓度2,4-D是一种苯氧羧酸类除草剂,被广泛应用于控制谷类和牧草中的阔叶杂草。研究以2份麦田黑土为材料,以2,4-D田间用量的10倍和100倍分别处理,在56 d的监测时间内研究土壤微生物对高浓度2,4-D的响应及降解特性。结果表明,在田间使用剂量的10倍即50 mg kg-1处理时,无论有无2,4-D施用历史,土壤中的微生物都可以适应2,4-D并产生降解反应,但有施用历史的土壤中2,4-D的降解半衰期更短。而田间使用剂量的100倍即500 mg kg-1处理时对土壤微生物有强烈的抑制作用。

Synthesis and bioactivity of novel 3-(1-hydroxyethylidene)-5-substituted-pyrrolidine-2,4-dione derivatives

Ten novel 5-substituted derivatives of 3-（1-hydroxyethylidene）pyrrolidine-2,4-dione were synthesized. The compounds were confirmed by IR, 1H NMR, MS and elemental analysis. The bioassay indicated that these compounds showed noticeable herbicidal activities, and compounds 6f and 6j exhibited excellent inhibitory activities against the stalk of Echinochloa crusgalli, with ECso values of 94.4 and 72.7 rag/L, respectively.