The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
J Perezpena - One of the best experts on this subject based on the ideXlab platform.
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photocatalytical removal of Bentazon using commercial and sol gel synthesized nanocrystalline tio2 operational parameters optimization and toxicity studies
Chemical Engineering Journal, 2012Co-Authors: E I Seck, J M Donarodriguez, C Fernandezrodriguez, O Gonzalezdiaz, J Arana, J PerezpenaAbstract:Abstract In this work we compared the photocatalytic activity of sol–gel synthesized nanocrystalline TiO2 material (ECT-1023t) and a commercial TiO2 (Degussa P25) in the elimination, mineralization and detoxification of waters contaminated by the herbicide Bentazon and its toxic intermediates under UV light. Adsorption and kinetics studies were undertaken and the effect of adding two different co-oxidants (H2O2 and S 2 O 8 2 - ) was analyzed for both photocatalysts. The optimal basic operating parameters (pH, photocatalyst load, initial concentration of Bentazon) to eliminate the herbicide and its toxic intermediates were established for both photocatalysts. The most efficient TiO2 for removal of Bentazon and its toxic intermediates was ECT-1023t at pH = 7. The apparent initial rate constant of Bentazon degradation was two times higher for ECT-1023t than for P25. A Langmuir–Hinshelwood kinetic model showed satisfactory Bentazon degradation of up to 0.25 mM for P25 and up to 0.05 mM for ECT-1023t. From FTIR studies, it seems that the interaction of Bentazon with both photocatalysts occurred through the SO2 group. The most efficient photocatalyst for detoxification of treated solution was ECT-1023t, using the marine bacteria Vibrio fischeri as the test organism. When using an initial Bentazon concentration of 0.265 mM, the evolution of toxicity saw a 72% reduction in bioluminescence inhibition for ECT-1023t and only a 33% reduction for P25 after 2 h of irradiation. No inhibitory growth effect of the herbicide Bentazon and its photoproducts was observed for either photocatalyst in any of the irradiated samples collected at predetermined times when Lemna minor was used as the test organism. In parallel, the three photoproducts formed in the earlier steps of Bentazon degradation were identified by LC–MS and a comparison on the evolution of these compounds by using both photocatalysts was performed. The results showed that the intermediates formed by hydroxylation of aromatic ring are in highest concentration when ECT-1023t is used. On the contrary, the hydroxylation of isopropyl group in Bentazon is the main pathway of Bentazon photodegradation when P25 is used as catalyst.
N Daneshvar - One of the best experts on this subject based on the ideXlab platform.
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removal of the herbicide Bentazon from contaminated water in the presence of synthesized nanocrystalline tio2 powders under irradiation of uv c light
Desalination, 2009Co-Authors: R Pourata, Alireza Khataee, Soheil Aber, N DaneshvarAbstract:Abstract A solution-based processing method has been used to synthesize nanocrystalline TiO 2 powders by controlling the hydrolysis of TiCl 4 in an aqueous solution in both anatase and rutile phases. The primary particle sizes of the powders were in the range of 5–15 nm. To determine the crystal phase composition and size of the prepared photocatalysts, X-ray diffraction (XRD) measurements were used. We also studied the photocatalytic removal of the herbicide, Bentazon, from contaminated water in the presence of synthesized nanocrystalline TiO 2 powders under UV light illumination (30 W). The removal efficiency of Bentazon was 16% when the photolysis was carried out in the absence of TiO 2 and it was negligible in the absence of UV light. We have studied the influence of the basic operational parameters such as the different kinds of TiO 2 , amount of TiO 2 , irradiation time and initial concentration of Bentazon on the photocatalytic removal efficiency of Bentazon. Our results indicated that 99% removal of the herbicide from the solution containing 15 ppm of Bentazon after selecting desired operational parameters could be achieved in a relatively short time, about 90 min. A kinetic model was successfully established for the prediction of removal of Bentazon by the UV/TiO 2 system with any concentration of the herbicide. In this work, we also compared the photocatalytic activity between the commercial TiO 2 and synthesized nanocrystalline TiO 2 powders. The photocatalytic activities of different photocatalysts were tested using the herbicide solution.
Robert M Zablotowicz - One of the best experts on this subject based on the ideXlab platform.
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Bentazon degradation in soil influence of tillage and history of Bentazon application
Journal of Agricultural and Food Chemistry, 1996Co-Authors: Stephen C Wagner, Robert M Zablotowicz, Lewis A Gaston, Martin A Locke, Jim KinsellaAbstract:Laboratory studies determined the fate of Bentazon (3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)one 2,2-dioxide) in soil as affected by tillage and history of application. Bentazon degradation in two soils from Mississippi and three soils from Illinois under conventional-tillage (CT) and notillage (NT) (3-18 years) with varying histories of Bentazon application (0-9 applications) was studied. The half-life (DT50) for Bentazon degradation ranged from 4.6 to 49.5 d; half-lives for NT of the two soils with the longest history of Bentazon application were lower than those for CT. Halflives for soils with no Bentazon history were 3-11-fold higher than Bentazon half-lives of those previously exposed to Bentazon. Dissipation of Bentazon was accompanied with increases in nonextractable material. MethylBentazon was the most consistently observed metabolite (1.75.8% applied 14 C after 48 d). Bentazon mineralization ranged from 12% to 18% applied after 48 d and 2% to 3% applied after 22 d for Bentazon history and nonhistory soils, respectively. Patterns of mineralization were affected by tillage in the two of the five soils with the longest Bentazon history.
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sorption and degradation of Bentazon in conventional and no till dundee soil
Journal of Environmental Quality, 1996Co-Authors: L A Gaston, Martin A Locke, Robert M ZablotowiczAbstract:Herbicides applied postemergence, such as Bentazon [3-(1-methyl-ethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide], reach the soil surface due to incomplete interception by the plant canopy or foliar washoff. Thus, potential off-site transport is influenced by sorption equilibrium/kinetics and degradation. This study addressed the effects of tillage practice on the sorption and degradation of 14 C-labeled Bentazon using Dundee silt loam soil (fine-silty, mixed, thermic, Aeric Ochraqualf) taken from the conventional-till (CT) and no-till (NT) treatments of a tillage experiment without Bentazon exposure for more than 3 yr. Data were generated for surface and subsurface samples. The kinetics of Bentazon sorption in CT surface soil were rapid, with apparent equilibrium achieved in 1 h. Furthermore, the extent of sorption was low and the equilibrium distribution of solution and sorbed Bentazon could be described using a linear model. Differences in soil organic matter between tillage treatments and with depth were not reflected in sorption behavior. However, degradation was more rapid in the CT surface soil than in the corresponding NT soil and more rapid in surface than subsurface soil. In all cases, degradation proceeded with little mineralization (<3%) over the 22-d duration of these experiments, however, the amount of unextractable 14 C (80 :20, CH 3 OH :0.01 M CaCl 2 extractant) increased with time. Analysis of the extractable fraction by HPLC gave no evidence of metabolites. Bentazon degradation was approximated using simple first-order kinetics, however, the data were best described using two-compartment models. Development of a bound 14 C fraction, despite limited Bentazon sorption and no evidence for extractable metabolites, suggested that metabolic intermediates exhibit high sorption affinity.
Martin A Locke - One of the best experts on this subject based on the ideXlab platform.
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Bentazon degradation in soil influence of tillage and history of Bentazon application
Journal of Agricultural and Food Chemistry, 1996Co-Authors: Stephen C Wagner, Robert M Zablotowicz, Lewis A Gaston, Martin A Locke, Jim KinsellaAbstract:Laboratory studies determined the fate of Bentazon (3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)one 2,2-dioxide) in soil as affected by tillage and history of application. Bentazon degradation in two soils from Mississippi and three soils from Illinois under conventional-tillage (CT) and notillage (NT) (3-18 years) with varying histories of Bentazon application (0-9 applications) was studied. The half-life (DT50) for Bentazon degradation ranged from 4.6 to 49.5 d; half-lives for NT of the two soils with the longest history of Bentazon application were lower than those for CT. Halflives for soils with no Bentazon history were 3-11-fold higher than Bentazon half-lives of those previously exposed to Bentazon. Dissipation of Bentazon was accompanied with increases in nonextractable material. MethylBentazon was the most consistently observed metabolite (1.75.8% applied 14 C after 48 d). Bentazon mineralization ranged from 12% to 18% applied after 48 d and 2% to 3% applied after 22 d for Bentazon history and nonhistory soils, respectively. Patterns of mineralization were affected by tillage in the two of the five soils with the longest Bentazon history.
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sorption and degradation of Bentazon in conventional and no till dundee soil
Journal of Environmental Quality, 1996Co-Authors: L A Gaston, Martin A Locke, Robert M ZablotowiczAbstract:Herbicides applied postemergence, such as Bentazon [3-(1-methyl-ethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide], reach the soil surface due to incomplete interception by the plant canopy or foliar washoff. Thus, potential off-site transport is influenced by sorption equilibrium/kinetics and degradation. This study addressed the effects of tillage practice on the sorption and degradation of 14 C-labeled Bentazon using Dundee silt loam soil (fine-silty, mixed, thermic, Aeric Ochraqualf) taken from the conventional-till (CT) and no-till (NT) treatments of a tillage experiment without Bentazon exposure for more than 3 yr. Data were generated for surface and subsurface samples. The kinetics of Bentazon sorption in CT surface soil were rapid, with apparent equilibrium achieved in 1 h. Furthermore, the extent of sorption was low and the equilibrium distribution of solution and sorbed Bentazon could be described using a linear model. Differences in soil organic matter between tillage treatments and with depth were not reflected in sorption behavior. However, degradation was more rapid in the CT surface soil than in the corresponding NT soil and more rapid in surface than subsurface soil. In all cases, degradation proceeded with little mineralization (<3%) over the 22-d duration of these experiments, however, the amount of unextractable 14 C (80 :20, CH 3 OH :0.01 M CaCl 2 extractant) increased with time. Analysis of the extractable fraction by HPLC gave no evidence of metabolites. Bentazon degradation was approximated using simple first-order kinetics, however, the data were best described using two-compartment models. Development of a bound 14 C fraction, despite limited Bentazon sorption and no evidence for extractable metabolites, suggested that metabolic intermediates exhibit high sorption affinity.
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Bentazon spray retention activity and foliar washoff in weed species
Weed Technology, 1995Co-Authors: Krishna N Reddy, Martin A Locke, Kevin D HowardAbstract:Greenhouse studies were conducted to investigate the effects of adjuvant and rainfall on Bentazon spray retention, efficacy, and foliar washoff in hemp sesbania, sicklepod, smooth pigweed, and velvetleaf. Bentazon was applied at 0.28 to 2.24 kg ai/ha with Agri-Dex, a crop oil concentrate (COC) or Kinetic, an organiosilicone-nonionic surfactant blend (OSB) when weeds were at the three- to five-leaf stage. Plants were subjected to 2.5 cm simulated rainfall for 20 min at 1 and 24 h after application of Bentazon. Shoot fresh weight reduction assessed 2 wk after treatment was similar with either adjuvant on velvetleaf and smooth pigweed. OSB enhanced Bentazon efficacy in hemp sesbania and sicklepod as compared to COC. Rainfall at 1 h after application generally reduced Bentazon activity in all weeds. OSB maintained Bentazon activity in hemp sesbania when subjected to rainfall at 1 h after application as compared to COC. Overall, Bentazon spray retention on plants was 9 to 550% higher with OSB as compared to COC among the species at 1 h after application. Amount of Bentazon residue washed off from the foliage by rainfall within a weed species was relatively similar for both adjuvants except in smooth pigweed and ranged from 39 to 98% among the four weed species at 1 h after application. OSB exhibited specificity for certain weed species and the potential to minimize Bentazon spray reaching the soil by increasing deposition.
E I Seck - One of the best experts on this subject based on the ideXlab platform.
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photocatalytical removal of Bentazon using commercial and sol gel synthesized nanocrystalline tio2 operational parameters optimization and toxicity studies
Chemical Engineering Journal, 2012Co-Authors: E I Seck, J M Donarodriguez, C Fernandezrodriguez, O Gonzalezdiaz, J Arana, J PerezpenaAbstract:Abstract In this work we compared the photocatalytic activity of sol–gel synthesized nanocrystalline TiO2 material (ECT-1023t) and a commercial TiO2 (Degussa P25) in the elimination, mineralization and detoxification of waters contaminated by the herbicide Bentazon and its toxic intermediates under UV light. Adsorption and kinetics studies were undertaken and the effect of adding two different co-oxidants (H2O2 and S 2 O 8 2 - ) was analyzed for both photocatalysts. The optimal basic operating parameters (pH, photocatalyst load, initial concentration of Bentazon) to eliminate the herbicide and its toxic intermediates were established for both photocatalysts. The most efficient TiO2 for removal of Bentazon and its toxic intermediates was ECT-1023t at pH = 7. The apparent initial rate constant of Bentazon degradation was two times higher for ECT-1023t than for P25. A Langmuir–Hinshelwood kinetic model showed satisfactory Bentazon degradation of up to 0.25 mM for P25 and up to 0.05 mM for ECT-1023t. From FTIR studies, it seems that the interaction of Bentazon with both photocatalysts occurred through the SO2 group. The most efficient photocatalyst for detoxification of treated solution was ECT-1023t, using the marine bacteria Vibrio fischeri as the test organism. When using an initial Bentazon concentration of 0.265 mM, the evolution of toxicity saw a 72% reduction in bioluminescence inhibition for ECT-1023t and only a 33% reduction for P25 after 2 h of irradiation. No inhibitory growth effect of the herbicide Bentazon and its photoproducts was observed for either photocatalyst in any of the irradiated samples collected at predetermined times when Lemna minor was used as the test organism. In parallel, the three photoproducts formed in the earlier steps of Bentazon degradation were identified by LC–MS and a comparison on the evolution of these compounds by using both photocatalysts was performed. The results showed that the intermediates formed by hydroxylation of aromatic ring are in highest concentration when ECT-1023t is used. On the contrary, the hydroxylation of isopropyl group in Bentazon is the main pathway of Bentazon photodegradation when P25 is used as catalyst.