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...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.展开更多
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 technolog...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.展开更多
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-imprint...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.展开更多
<div style="text-align:justify;"> <span style="font-family:Verdana;">Medicinal plants have been used to treat many diseases with fewer side effects compared to clinical medicines. The n...<div style="text-align:justify;"> <span style="font-family:Verdana;">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 </span><i><span style="font-family:Verdana;">Lepidium sativum</span></i><span style="font-family:Verdana;"> 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 LD</span><sub><span style="font-family:Verdana;">50</span></sub><span style="font-family:Verdana;"> administration, protective group which was treated for 4 weeks with LS water extract prior to the 2, 4-D LD</span><sub><span style="font-family:Verdana;">50</span></sub><span style="font-family:Verdana;"> 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, </span><i><span style="font-family:Verdana;">Lepidium sativum </span></i><span><span style="font-family:Verdana;">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.</span></span> </div>展开更多
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 betwee...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.展开更多
This research was to study in vitro callus induction in Coconut cv MATAG from young leaf explants. Young leaf segments from mature coconut were cultured on Y3 medium supplemented with different concentrations of 2,4-D...This research was to study in vitro callus induction in Coconut cv MATAG from young leaf explants. Young leaf segments from mature coconut were cultured on Y3 medium supplemented with different concentrations of 2,4-D and a combination of NAA and BAP. Each of these plant growth regulators (PGR) gives different responses toward callus formation, the percentage of explants producing callus, the percentage of callus proliferation, and the morphology of callus. A series of different concentrations were used for 2,4-D (1, 5, 10, 20, 40, 60, 100 mg/L), NAA (1, 3, 5 mg/L) and BAP (1, 3, 5 mg/L) respectively. The range of days of callus formation using 2,4-D treatments is 7 - 12 months, while the 2,4-D combined with NAA is recorded at 2 - 5 months. Despite the variety of different months between these plant growth regulators for callus formation, the percentages of explants producing callus and callus proliferation are different. The highest percentage of explants producing callus (2.9%) was observed at 2,4-D (40 mg/mL), followed by 2.7% at 2,4-D (10.0 mg/mL) with NAA (1 mg/mL). At a concentration of 100 mg/mL of 2,4-D, the highest percentage of callus proliferation was found, as well.展开更多
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 dic...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.展开更多
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 construct...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.展开更多
基金The National Natural Science Foundation of China (No. 50378028)
文摘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.
文摘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.
基金supported by the Natural Science Foundation of Zhejiang Province(No.Y505073)the Scientific Project of Zhejiang Province(No.2008C22012)
文摘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.
文摘<div style="text-align:justify;"> <span style="font-family:Verdana;">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 </span><i><span style="font-family:Verdana;">Lepidium sativum</span></i><span style="font-family:Verdana;"> 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 LD</span><sub><span style="font-family:Verdana;">50</span></sub><span style="font-family:Verdana;"> administration, protective group which was treated for 4 weeks with LS water extract prior to the 2, 4-D LD</span><sub><span style="font-family:Verdana;">50</span></sub><span style="font-family:Verdana;"> 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, </span><i><span style="font-family:Verdana;">Lepidium sativum </span></i><span><span style="font-family:Verdana;">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.</span></span> </div>
基金the deanship of scientific Research at Princess Nourah bint Abdulrahman University through the Fast-track Research Funding program。
文摘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.
文摘This research was to study in vitro callus induction in Coconut cv MATAG from young leaf explants. Young leaf segments from mature coconut were cultured on Y3 medium supplemented with different concentrations of 2,4-D and a combination of NAA and BAP. Each of these plant growth regulators (PGR) gives different responses toward callus formation, the percentage of explants producing callus, the percentage of callus proliferation, and the morphology of callus. A series of different concentrations were used for 2,4-D (1, 5, 10, 20, 40, 60, 100 mg/L), NAA (1, 3, 5 mg/L) and BAP (1, 3, 5 mg/L) respectively. The range of days of callus formation using 2,4-D treatments is 7 - 12 months, while the 2,4-D combined with NAA is recorded at 2 - 5 months. Despite the variety of different months between these plant growth regulators for callus formation, the percentages of explants producing callus and callus proliferation are different. The highest percentage of explants producing callus (2.9%) was observed at 2,4-D (40 mg/mL), followed by 2.7% at 2,4-D (10.0 mg/mL) with NAA (1 mg/mL). At a concentration of 100 mg/mL of 2,4-D, the highest percentage of callus proliferation was found, as well.
文摘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.
基金supported by grants from the National Key Scientific Instrument and Equipment Development Project(No.2012YQ03011108)research fund program of Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology(No.2016K0013)+1 种基金the National Natural Science Foundation of China(Grant Nos.51608547,51278500 and 51308557)the Fundamental Research Funds for the Central Universities(No.16lgjc65).
文摘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.
