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.

Design of 2,4-Dichlorophenoxyacetic Acid Imprinted Polymer with High Specificity and Selectivity

A widely used herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) was imprinted on poly (4-vinylpyridine) (4-VP) using (40%) ethyleneglycol dimethacrylate (EGDMA) as crosslinking agent. The classical imprinting technology makes use of a high degree of crosslinking which does not allow the template molecules to move freely. So the binding sites, located in the central area of the three dimensional polymer matrix are hard to be accessed and the template molecules cannot be extracted totally. But here we propose a low crosslinked system with high specificity and selectivity. The imprinted and non-imprinted polymers were characterized by various spectroscopic techniques. The extent of binding was followed by batch equilibration method and compared with the respective non-imprinted polymer. Conditions for maximum specific rebinding were set by altering certain factors like template/monomer ratio, concentration of template solution, rebinding medium, mass of polymer and time of incubation. The selectivity of the imprinted polymer was investigated by comparing the binding with structural analogues of 2,4-D like, phenoxyacetic acid (POA), 4-chlorophenoxyacetic acid (4-CPOA) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). The imprinted polymer exhibited high affinity towards the template molecule and was selectively rebound to the specific sites. The binding towards the structural analogues depends on the number of chlorine in the benzene ring.

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.

2,4-D处理对发育过程中欧李果实钙与有机酸代谢影响及变化关系

以内蒙古地区欧李为试验材料,对结果枝进行2,4-D处理,测定果实在不同发育阶段的钙和有机酸质量分数及相关代谢酶活性,并进行相关性分析。结果表明:(1)在果实发育过程中,2,4-D处理的果实中总钙、水溶性钙、果胶钙、磷酸钙和草酸钙都明显高于对照,在硬核期和着色膨大期表现尤为突出。(2)2,4-D处理的果实中有机酸增加,苹果酸和柠檬酸的质量分数增加明显,而草酸质量分数有所下降;2,4-D处理明显增强了苹果酸脱氢酶(NAD-MDH)活性,进而促进了苹果酸质量分数的升高和柠檬酸质量分数的下降。(3)相关性分析显示,欧李果实中苹果酸与水溶性钙呈显著正相关,而柠檬酸和草酸则与非水溶性钙及总钙呈显著正相关。综上,2,4-D处理对欧李果实中钙积累和有机酸代谢具有积极影响,通过影响有机酸代谢酶的活性,果实中有机酸含量均明显增加,苹果酸的增加促进水溶性钙的积累,柠檬酸和草酸的增加促进非水溶性钙的积累,从而提升果实中总钙质量分数。

Protective Effect of <i>Lepedium sativum</i>against 2, 4-Dichlorophenoxyacetic Acid Hepatotoxicity: An Electron Microscopic Study

Medicinal plants have been used to treat many diseases with fewer side effects compared to clinical medicines. The need for treatment by medicinal plants has been increasing in response to the accumulation of environmental pollutants. The herbicide 2, 4-Dichlorophenoxyacetic acid has been considered as fast spreadable environmental pollutant, which may cause many disorders in animals and possibly in humans. The aim of this study is to assess the protective and/or curative effect of Lepidium sativum against hepatotoxicity induced by 2, 4-D herbicide in rats. 25 Albino Wistar rats were grouped into 4 groups: a control group, the curative group treated for 4 weeks with LS water extract after a single dose 2, 4-D LD50 administration, protective group which was treated for 4 weeks with LS water extract prior to the 2, 4-D LD50 administration, and LS only group that was given the LS water extract as a positive control. Using transmission electron microscope, the histological features showed that curative group hepatocytes still suffered from focal necrosis and vacuolation of hepatocytes as a result of 2, 4-D toxic effect whereas in the protective group hepatocytes were less accentuated expressed as less frequent necrotic area, and still large mitochondria were present with numerous undissolved lipid droplets and a small amount of rough endoplasmic reticulum. For the LS only group, nearly normal cells with centric nucleus, normal small mitochondria were at a normal nucleus-cytoplasmic ratio, but a few lipid droplets were noticed. This study proved that curative group has an advantage over the protective group that could be presented in the nucleus with narrow nuclear pores and intact nuclear envelope with dense small mitochondria and normal rough endoplasmic reticulum that were recorded as in the control group. Thus, Lepidium sativum administration to the rats prior or post to intoxication was effective in minimizing the 2, 4-D-induced damages likely through a free radical scavenging activity in liver tissue.

Fe/Co双金属材料活化过一硫酸盐氧化降解水中2,4-D

为了处理有机氯除草剂2,4-二氯苯氧乙酸(2,4-D)造成的环境污染,本研究采用液相还原法制备了铁钴双金属纳米颗粒(n-Fe/Co),并通过Fe、Co的合成比例优化了活化过一硫酸盐(PMS)体系对2,4-D的降解性能。结果表明:在pH为4.5的条件下,使用0.03 g·L^(-1)的n-Fe/Co和0.5 mmol·L^(-1)的PMS,2,4-D(10 mg·L^(-1))在30 min内完全去除,与单纯的纳米零价铁(nZVI)相比,2,4-D的去除率提升了60.9个百分点。n-Fe/Co可以在很宽的pH范围(2~9)和复杂的阴离子条件下有效去除2,4-D。自由基抑制实验表明羟基自由基是参与反应的主要活性物种(贡献率达到62.2%)。在中间产物分析的基础上,提出了2,4-D在n-Fe/Co-PMS体系中的降解机理和降解途径。研究表明,n-Fe/Co复合材料活化PMS系统在处理水中的2,4-D除草剂污染方面有很大的应用前景。

氮磷钾配施、外源水杨酸和2,4-D丁酯对籽实谷子产量的影响

为优化杂交谷生产中施肥方案,以‘张杂谷5号’为材料,采用5因素二次通用旋转组合设计,在大田条件下探讨氮、磷、钾肥、水杨酸和除草剂2,4-D丁酯对谷子[Setaria italica(L.)Beauv.]净光合速率、叶面积指数、丙二醛及籽实产量的影响。结果显示,净光合速率、叶面积指数、丙二醛及籽实产量在5个因素的作用下均呈抛物线状变化。单因素分析表明氮、磷、钾和水杨酸浓度对谷子籽实产量均有显著影响(P<0.05),交互作用显示氮和水杨酸、氮和2,4-D丁酯、水杨酸和2,4-D丁酯交互作用对产量影响显著(P<0.05)。‘张杂谷5号’单位面积籽实产量最大的农艺方案为施用氮肥185.6 kg·hm^(-2),磷肥94.5 kg·hm^(-2),水杨酸0.64 g·L^(-1),钾肥49.3 kg·hm^(-2),2,4-D丁酯651.9 mL·hm^(-2),此时谷子籽实产量为6783.18 kg·hm^(-2)。

胺鲜酯和2,4-二氯苯氧乙酸协同诱导裂殖壶菌积累DHA

目前添加植物生长调节剂是一种促进裂殖壶菌中二十二碳六烯酸(DHA)积累以及提高其产量很有潜力的策略。添加单一植物生长调节剂促进裂殖壶菌DHA积累已有报道,但同时添加两种植物生长调节剂协同促进裂殖壶菌中DHA积累鲜见报道。本工作采用合成植物生长调节剂胺鲜酯(DA-6)和2,4-二氯苯氧乙酸(2,4-D)协同诱导裂殖壶菌积累DHA,提高DHA含量和产量,以DHA为指标优化了DA-6和2,4-D的最佳协同浓度。结果表明:0.05mg/L DA-6和0.5mg/L 2,4-D协同处理裂殖壶菌,裂殖壶菌生物量和油脂含量没显著增加,但DHA含量和产量显著增加,分别达到58.32%和5.17g/L,相比于单独添加DA-6分别增加17%和23%,相比于未添加植物生长调节剂的空白对照组分别增加了48%和48%。本研究表明适宜浓度的合成植物生长调节剂可协同诱导裂殖壶菌中DHA的积累,提高DHA产量,为大规模工业化生产DHA提供新的思路和策略。

Pd/CeO_(2)对2,4-二氯苯氧乙酸的液相催化加氢脱氯

采用NaBH4还原法分别制备了不同载体CeO_(2)、活性炭(AC)和石英砂(SiO_(2))的负载型Pd基催化剂。采用Zeta电位、X射线衍射、透射电子显微镜等手段对催化剂进行表征,并利用高活性Pd/CeO_(2)催化剂对2,4-二氯苯氧乙酸(2,4-D)进行液相加氢脱氯反应研究。研究结果表明:载体对催化剂活性影响较大,其中Pd/CeO_(2)催化剂具有高等电点、较强的金属-载体相互作用以及Pd颗粒高分散度的活性特征;Pd/CeO_(2)催化剂对2,4-D的脱氯效果随Pd负载量增加而增加,随pH值的增加呈现先升高后降低的趋势;Pd/CeO_(2)催化剂对2,4-D的加氢脱氯反应符合Langumir-Hinshelwood模型,表明2,4-D在催化剂表面的吸附是反应的速率控制步骤,且Pd/CeO_(2)对不同的污染物都表现出较高的液相加氢还原活性。

LC-MS/MS法测定2,4-D在土壤中的残留研究

建立了一种土壤中2,4-D的液相色谱-串联质谱的检测分析方法。样品经酸化乙腈提取,浓缩定容后过0.22μm微孔滤膜,采用色谱柱分离,以乙腈和0.25%甲酸溶液为流动相进行梯度洗脱,采用电喷雾ESI离子源方式和多信号扫描,外标法定量。在10.0~1000μg/kg的质量浓度范围内,相关系数R^(2)为0.9999,该方法的定量检测限为10.0μg/kg。进行100μg/kg、200μg/kg和1000μg/kg三个不同水平浓度的添加回收试验,2,4-D的回收率在75.91%~98.05%之间,RSD介于5.94%~18.75%之间。该方法操作简单、灵敏度高、快速准确。利用该方法测定土壤中2,4-D残留量,施药后2 h 2,4-D在土壤上的原始附着量为73.4μg/kg,第21天残留量为≤10.0μg/kg,消解率为≥86.38%,半衰期T1/2为5.42 d。

基于4-(2,4-二羧基苯氧基)邻苯二甲酸配体的锌配位聚合物的合成、结构及其荧光传感性能

基于H_(4)dpa和bpy(H_(4)dpa=4-(2,4-二羧基苯氧基)邻苯二甲酸,bpy=4,4’-联吡啶)为配体,在水热条件下设计、合成了金属锌配位聚合物(Zn-CP)[Zn(H_(2)dpa)(bpy)_(1.5)]_(n)(1),并用元素分析、红外光谱、X射线单晶衍射等对其进行了结构表征。在1中相邻Zn^(2+)与H_(2)dpa^(2-)离子和bpy配位形成一维双链结构,相邻的一维双链通过氢键作用扩展形成三维超分子网结构。荧光研究表明:1是一种灵敏度高、选择性好、多响应的荧光传感器,可用于农药和硝基爆炸物的检测。有趣的是,2,4,6-三硝基苯(TNP)和嘧霉胺(Pth)对1的荧光发射显示出明显的猝灭效果,而抑霉唑(Ima)对1有荧光增强效果。此外,通过紫外可见吸收光谱、荧光寿命以及X射线光电子能谱探究了1的荧光传感机理。

二次萃取法提纯2,4-D废水中氯代酚

以二甲苯为萃取剂,通过二次萃取的方式,对2,4-二氯苯氧乙酸废水进行处理。研究了萃取剂种类、油水比、废水pH值以及反萃液的pH值对提纯氯代酚的影响。结果表明一次萃取油水比为0.4/1,pH在4.60～4.62,一次反萃液的pH值在5.05左右,氯代酚萃取效率达到最高。使得废水中的氯代酚能够返回生产循环利用。

Structures and Photoluminescent Properties of Two Complexes Based on Dipyrido[3,2-a：2？,3？-c]phenazine and 2,4＇-Biphenyldicarboxylic Acid

ABSTRAC Two new complexes [Cd（2,4＇-bpdc）（DPPZ）]2n·n H2O（1） and [Zn（2,4＇-Hbpdc）2（DPPZ）]· H2O（DPPZ = dipyrido[3,2-a：2＇,3＇-c]phenazine, 2,4＇-H2bpdc = 2,4＇-biphenyldicarboxylic acid） have been hydrothermally synthesized. The structure of complex 1 was determined by single-crystal X-ray diffraction diffraction and further characterized by elemental analysis, IR spectrum, powder X-ray diffraction（XRD） and single-crystal X-ray diffraction. Complex 1 has 1D chains, which are further connected by π-π stacking interactions of neighbouring chains, generating a steady 3D supramolecular structure. Complex 2 shows the isolated mononuclear units, which are further extended to a 2D supramolecular layered structure through π-π stacking interactions and hydrogen bonds. Furthermore, complexes 1 and 2 exhibit green photoluminescent properties at room temperature.

ADSORPTION OF 2,4-DICHLOROBENZOXYACETIC ACID ONTO HYPERCROSSLINKED RESIN MODIFIED BY PHENOLIC HYDROXYL GROUP (AM-1)

An experimental comparison of the adsorption properties of hypercrosslinked resin AM-1 modified by phenolic hydroxyl group with Amberlite XAD-4 toward 2,4-dichlorobenzoxyacetic acid was performed. This paper focuses on the static equilibrium adsorption behaviors and the adsorption thermodynamics. Two isotherm models were used to explain the results. It is seen that the Langmuir equation can give a perfect fit. The adsorption capacities from the different ranges of temperature, the adsorption enthalpy change value and the comparison of desorption conditions lead to the same conclusion that the adsorption of 2,4-dichlorobenzoxyacetic acid from water onto AM-1 is a type of physical and chemical transition.

A New Synthetic Route for 2,4-Dibromo-5-fluorobenzoic Acid

A convenient and practical synthetic route for 2,4-dibromo-5-fluorobenzoic acid is described. Two intermediates, 2,4-dibromo-5-fluorobenzonitrile and 2,4-dibromo-5-fluorobenzamide, have not been reported before. This route can be easily industrialized.

HPLC Determination of Neurotoxin β-N-oxalyl-L-α, β-diaminopropionic acid and Its α -Isomer in Lathyrus sativus by Precolumn Derivatisation with 1-Fluoro-2,4-dinitrobenzcne

A rapid and simple method is presented for determining β-N-oxalyl-α. β- diaminopropionic acid (β -ODAP) and its much less toxic α -isomer (α -ODAP) in Lathyrus sativus. Seed and foliage extracts of Lathyrus sativus were treated with 1-fluoro-2,4-dinitrobenzene (FDNB) and a reversed-phase high-performance liquid chromatographic method for the separation of the derivatives in the pmol range is reported.

Kinetics of 2,4-dichlorophenol dechlorination by Pd-Fe bimetallic nanoparticles in the presence of humic acid

The remediation of groundwater which contains chlorinated organic compounds (COCs) by nanoscale bimetallic catalysts has received increasing interest in recent years. This report presents the dechlorination of 2,4-dichlorophenol (2,4-DCP) by Pd-Fe bimetallic nanoparticles in the presence of humic acid (HA) to investigate the feasibility of using Pd-Fe for the in situ remediation of contaminated groundwater. Our experimental results indicated that HA had an adverse effect on the dechlorination of 2,4-DCP by Pd-Fe nanoparticles. The rate constant k values of 2,4-DCP dechlorination were 0.017, 0.013, 0.009, 0.006 and 0.004 min?1 for HA concentrations of 0, 5, 10, 15 and 20 mg/L, respectively. The relationship between HA dosage and k values can be described as a linear model.

超高效液相色谱/串联质谱法测定水体中2,4-滴

建立超高效液相色谱-三重四极杆串联质谱(UPLC-MS/MS)快速测定水中2,4-滴的方法。水样过滤后直接进样,以体积分数为30%的乙酸铵-70%乙腈作为流动相进行等度洗脱,负离子模式下,采用多反应监测(MRM)模式检测。结果表明,2,4-滴在0.2~40μg/L质量浓度范围内线性关系良好(r> 0.999),加标回收率平均值为91.1%~114.6%,精密度(RSD)为1.2%~12.9%,方法检出限为0.03μg/L。该方法快速、高效、简洁、绿色,适用于水体中2,4-滴的测定。

绿茶、乌龙茶和红茶提取物对2,4-二氯苯氧乙酸诱导的斑马鱼胚胎形态发育毒害的影响

目的研究绿茶提取物(green tea extract,GTE)、乌龙茶提取物(Oolong tea extract,OTE)和红茶提取物(black tea extract,BTE)对2,4-二氯苯氧乙酸(2,4-dichlorophenoxyacetic acid,2,4-D)导致的斑马鱼胚胎发育毒害的影响。方法用50 mg/L 2,4-D分别联合6.25、12.50和25.00 mg/L GTE,6.25、12.50和25.00 mg/L OTE以及50、100和150 mg/L BTE处理斑马鱼胚胎至96 hpf,体视显微镜观察斑马鱼胚胎发育并统计孵化率、死亡率、畸形率,测定斑马鱼心跳次数、体长、卵黄和心包面积。结果各处理组斑马鱼胚胎孵化正常。除2,4-D+BTE处理组随BTE浓度提高死亡率升高,其他处理组没有发生显著死亡。GTE降低2,4-D导致的斑马鱼胚胎畸变率,提高2,4-D导致的心跳下降和体长缩短,缩小2,4-D导致的卵黄和心包面积;相反,BTE加重2,4-D导致的斑马鱼胚胎形态发育毒害;而OTE对2,4-D导致的斑马鱼胚胎发育毒害无明显影响。结论GTE、OTE和BTE对2,4-D导致的斑马鱼胚胎发育毒害分别具有拮抗作用、无作用和协同作用。