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Stephen J Klaine - One of the best experts on this subject based on the ideXlab platform.
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Influence of plant age and size on Simazine toxicity and uptake.
Journal of Environmental Quality, 2002Co-Authors: S. L. Knuteson, Ted Whitwell, Stephen J KlaineAbstract:Improper pesticide management can lead to environmental problems such as water quality degradation and ecological stress. Recent research in our laboratory has focused on development of constructed wetlands to assimilate pesticide-contaminated water. For improved aesthetics, these wetlands have been established with ornamental plant species. The effectiveness of a plant species for phytoremediation depends in part on its tolerance for the contaminant. Plant tolerance for pesticides may vary depending on plant age and size. This study examined the influence of plant age and size on the uptake, distribution, and toxicity of the herbicide Simazine [2-chloro-4,6-bis(ethylamino)-1,3,5-triazine] in two ornamental wetland plants: parrot feather [Myriophyllum aquaticum (Vell.) Verdc.] and canna (Canna × hybrida L. 'Yellow King Humbert'). Plants of different ages and sizes were exposed to Simazine in 10% Hoagland's nutrient solution. Toxicity was characterized using plant growth, water uptake, and photosynthetic yield during exposure and postexposure periods. In addition, other plants were exposed to [ 14 C] Simazine in nutrient medium to characterize pesticide uptake and translocation. Four-week-old parrot feather and canna were more tolerant of Simazine than two-week-old plants. The two-week-old plant tissues of both species had higher tissue burdens of Simazine than four-week-old plants. Simazine was primarily accumulated in the leaves of both parrot feather and canna. These results suggest that plants in a constructed wetland designed for Simazine assimilation would be more vulnerable to Simazine toxicity shortly after emergence.
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metalaxyl and Simazine toxicity to and uptake by typha latifolia
Archives of Environmental Contamination and Toxicology, 2000Co-Authors: P C Wilson, Ted Whitwell, Stephen J KlaineAbstract:This research focused on the potential use of common cattails (Typha latifolia) for removing metalaxyl and Simazine residues from contaminated water. Specifically, it established toxicity thresholds to the herbicide Simazine and characterized the uptake and distribution of Simazine and metalaxyl by the plants. Simazine tolerance levels were determined by exposing plants to a series of six concentrations (0–3.0 mg L−1) in aqueous nutrient media for 7 days. Metalaxyl toxicity was not evaluated because other studies indicated it was relatively nontoxic to plants. Toxicity endpoints measured included fresh mass production after 7 days of exposure and 7 days postexposure. Pesticide uptake and distribution were determined by growing plants in nutrient media amended with 14C-ring-labeled metalaxyl (0.909 mg L−1) or Simazine (0.242 mg L−1) for 1, 3, 5, or 7 days. Plants were dissected, and tissues were combusted and analyzed by liquid scintillation spectroscopy. Cattail fresh mass production was reduced 84 and 117% at 1.0 and 3.0 mg L−1 Simazine, respectively, after 7 days of exposure. Metalaxyl and Simazine activity in solution was reduced 34 and 65%, respectively, after 7 days. By day 7, activity from both pesticides was detected predominantly in the leaves. Uptake of each pesticide was correlated with water uptake throughout the 7 days. These results suggest that the common cattail may be a good candidate for incorporation into a phytoremediation scheme for metalaxyl and Simazine.
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408 Potential Use of Typha latifolia for Bioremediation of Metalaxyl and Simazine
Hortscience, 2000Co-Authors: C. Wilson, Stephen J Klaine, Ted WhitwellAbstract:This research focused on the potential use of common cattails (Typha latifolia) for removing metalaxyl and Simazine residues from contaminated water. Specifically, it established toxicity thresholds to the herbicide Simazine and characterized the uptake and distribution of Simazine and metalaxyl by the plants. Simazine tolerance levels were determined by exposing plants to a series of six concentrations (0 to 3.0 mg/L) in aqueous nutrient media for 7 days. Metalaxyl toxicity was not evaluated because other studies indicated it was relatively non-toxic to plants. Toxicity endpoints measured included fresh mass production after 7 days exposure and 7 days post-exposure. Pesticide uptake and distribution were determined by growing plants in nutrient media amended with C-14-ring-labeled metalaxyl (0.909 mg/L) or Simazine (0.242 mg/L) for 1, 3, 5, or 7 days. Plants were dissected and tissues were combusted and analyzed by liquid scintillation counting. Cattail fresh mass production was reduced 84% and 117% at 1.0 and 3.0 mg/L Simazine, respectively, after 7 days of exposure. Metalaxyl and Simazine activity in solution was reduced 34% and 65%, respectively, after 7 days. By day 7, activity from both pesticides was detected predominantly in the leaves. Uptake of each pesticide was correlated with water uptake throughout the 7 days. These results suggest that the common cattail may be a good candidate for incorporation into a phytoremediation scheme for metalaxyl and Simazine.
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phytotoxicity uptake and distribution of 14c Simazine in canna hybrida yellow king humbert
Environmental Toxicology and Chemistry, 1999Co-Authors: Chris P Wilson, Ted Whitwell, Stephen J KlaineAbstract:Phytoremediation depends on the ability of plants to tolerate and assimilate contaminants. We have been interested in the use of common ornamental plants to ameliorate the impacts of pesticide waste on golf courses and ornamental plant nurseries. This research characterized the interaction between an ornamental, Canna hybrida ‘Yellow King Humbert,’ and the herbicide Simazine. Simazine tolerance levels for C. hybrida were determined by exposing plants for 7 d to 0, 0.01, 0.03, 0.1, 0.3, 1.0, or 3.0 mg-Simazine/L aqueous nutrient media. Response endpoints included fresh mass production after 7 d of exposure and 7 d postexposure and quantum efficiency using dark-adapted and light-adapted plants. Simazine uptake and distribution within the plant was determined by exposing plants to 2.02 μCi [14C]Simazine in nutrient media (0.242 mg/L) for 1, 3, 5, or 7 d. Plant tissues were combusted and analyzed by liquid scintillation counting. Fresh mass production was reduced 66 and 78% for plants exposed to 1.0 and 3.0 mg/L, respectively. Photosynthetic efficiency measured in dark-adapted plants was reduced 34 and 60% at the same respective concentrations, whereas photosynthetic efficiency measured in light-adapted plants was reduced 76 and 92%, respectively. Simazine activity in solution was reduced 80% over 7 d. By day 7, Simazine (and/or an impurity) was distributed throughout the plant, but predominantly occurred in the leaves. Uptake of Simazine was correlated with water uptake throughout the 7 d. These results suggest that C. hybrida may be a good candidate for incorporation into a phytoremediation scheme for Simazine.
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Toxicity, Uptake, and Distribution of Simazine in Canna hybrida `King Humbert': Implications for Phytoremediation
Hortscience, 1998Co-Authors: Patrick C. Wilson, Ted Whitwell, Stephen J KlaineAbstract:This research focuses on the potential use of Canna hybrida `King Humbert' for removing Simazine from contaminated water generated at golf courses and ornamental nurseries. Because of Simazine's herbicidal activity, it is important for levels in solution not to exceed plant tolerance levels. Tolerance levels for C. hybrida were determined by dosing plants for 7 d with 0, 0.01, 0.03, 0.1, 0.3, 1.0, or 3.0 mg Simazine/L nutrient media. Measurements of 7-d fresh mass production and photosynthetic efficiency (Fv/Fm) were taken. Simazine uptake and distribution within the plant was determined by dosing plants with 2.03 mCi 14C-Simazine (0.243 mg/L) for 1, 3, 5, or 7 d. Plant tissues were analyzed by combustion and liquid scintillation counting. Fresh mass production was reduced 66% and 78% for plants exposed to 1.0 and 3.0 mg/L, respectively. Likewise, photosynthetic efficiency was reduced to 66% and 40% of the controls at the same respective concentrations. Plant uptake of Simazine accounted for 13%, 34%, 48%, and 65% of the original Simazine in the dosing solution after 1-, 3-, 5-, and 7-d exposure, respectively. This Simazine was distributed primarily between roots and leaves.
Ted Whitwell - One of the best experts on this subject based on the ideXlab platform.
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Influence of plant age and size on Simazine toxicity and uptake.
Journal of Environmental Quality, 2002Co-Authors: S. L. Knuteson, Ted Whitwell, Stephen J KlaineAbstract:Improper pesticide management can lead to environmental problems such as water quality degradation and ecological stress. Recent research in our laboratory has focused on development of constructed wetlands to assimilate pesticide-contaminated water. For improved aesthetics, these wetlands have been established with ornamental plant species. The effectiveness of a plant species for phytoremediation depends in part on its tolerance for the contaminant. Plant tolerance for pesticides may vary depending on plant age and size. This study examined the influence of plant age and size on the uptake, distribution, and toxicity of the herbicide Simazine [2-chloro-4,6-bis(ethylamino)-1,3,5-triazine] in two ornamental wetland plants: parrot feather [Myriophyllum aquaticum (Vell.) Verdc.] and canna (Canna × hybrida L. 'Yellow King Humbert'). Plants of different ages and sizes were exposed to Simazine in 10% Hoagland's nutrient solution. Toxicity was characterized using plant growth, water uptake, and photosynthetic yield during exposure and postexposure periods. In addition, other plants were exposed to [ 14 C] Simazine in nutrient medium to characterize pesticide uptake and translocation. Four-week-old parrot feather and canna were more tolerant of Simazine than two-week-old plants. The two-week-old plant tissues of both species had higher tissue burdens of Simazine than four-week-old plants. Simazine was primarily accumulated in the leaves of both parrot feather and canna. These results suggest that plants in a constructed wetland designed for Simazine assimilation would be more vulnerable to Simazine toxicity shortly after emergence.
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metalaxyl and Simazine toxicity to and uptake by typha latifolia
Archives of Environmental Contamination and Toxicology, 2000Co-Authors: P C Wilson, Ted Whitwell, Stephen J KlaineAbstract:This research focused on the potential use of common cattails (Typha latifolia) for removing metalaxyl and Simazine residues from contaminated water. Specifically, it established toxicity thresholds to the herbicide Simazine and characterized the uptake and distribution of Simazine and metalaxyl by the plants. Simazine tolerance levels were determined by exposing plants to a series of six concentrations (0–3.0 mg L−1) in aqueous nutrient media for 7 days. Metalaxyl toxicity was not evaluated because other studies indicated it was relatively nontoxic to plants. Toxicity endpoints measured included fresh mass production after 7 days of exposure and 7 days postexposure. Pesticide uptake and distribution were determined by growing plants in nutrient media amended with 14C-ring-labeled metalaxyl (0.909 mg L−1) or Simazine (0.242 mg L−1) for 1, 3, 5, or 7 days. Plants were dissected, and tissues were combusted and analyzed by liquid scintillation spectroscopy. Cattail fresh mass production was reduced 84 and 117% at 1.0 and 3.0 mg L−1 Simazine, respectively, after 7 days of exposure. Metalaxyl and Simazine activity in solution was reduced 34 and 65%, respectively, after 7 days. By day 7, activity from both pesticides was detected predominantly in the leaves. Uptake of each pesticide was correlated with water uptake throughout the 7 days. These results suggest that the common cattail may be a good candidate for incorporation into a phytoremediation scheme for metalaxyl and Simazine.
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408 Potential Use of Typha latifolia for Bioremediation of Metalaxyl and Simazine
Hortscience, 2000Co-Authors: C. Wilson, Stephen J Klaine, Ted WhitwellAbstract:This research focused on the potential use of common cattails (Typha latifolia) for removing metalaxyl and Simazine residues from contaminated water. Specifically, it established toxicity thresholds to the herbicide Simazine and characterized the uptake and distribution of Simazine and metalaxyl by the plants. Simazine tolerance levels were determined by exposing plants to a series of six concentrations (0 to 3.0 mg/L) in aqueous nutrient media for 7 days. Metalaxyl toxicity was not evaluated because other studies indicated it was relatively non-toxic to plants. Toxicity endpoints measured included fresh mass production after 7 days exposure and 7 days post-exposure. Pesticide uptake and distribution were determined by growing plants in nutrient media amended with C-14-ring-labeled metalaxyl (0.909 mg/L) or Simazine (0.242 mg/L) for 1, 3, 5, or 7 days. Plants were dissected and tissues were combusted and analyzed by liquid scintillation counting. Cattail fresh mass production was reduced 84% and 117% at 1.0 and 3.0 mg/L Simazine, respectively, after 7 days of exposure. Metalaxyl and Simazine activity in solution was reduced 34% and 65%, respectively, after 7 days. By day 7, activity from both pesticides was detected predominantly in the leaves. Uptake of each pesticide was correlated with water uptake throughout the 7 days. These results suggest that the common cattail may be a good candidate for incorporation into a phytoremediation scheme for metalaxyl and Simazine.
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phytotoxicity uptake and distribution of 14c Simazine in canna hybrida yellow king humbert
Environmental Toxicology and Chemistry, 1999Co-Authors: Chris P Wilson, Ted Whitwell, Stephen J KlaineAbstract:Phytoremediation depends on the ability of plants to tolerate and assimilate contaminants. We have been interested in the use of common ornamental plants to ameliorate the impacts of pesticide waste on golf courses and ornamental plant nurseries. This research characterized the interaction between an ornamental, Canna hybrida ‘Yellow King Humbert,’ and the herbicide Simazine. Simazine tolerance levels for C. hybrida were determined by exposing plants for 7 d to 0, 0.01, 0.03, 0.1, 0.3, 1.0, or 3.0 mg-Simazine/L aqueous nutrient media. Response endpoints included fresh mass production after 7 d of exposure and 7 d postexposure and quantum efficiency using dark-adapted and light-adapted plants. Simazine uptake and distribution within the plant was determined by exposing plants to 2.02 μCi [14C]Simazine in nutrient media (0.242 mg/L) for 1, 3, 5, or 7 d. Plant tissues were combusted and analyzed by liquid scintillation counting. Fresh mass production was reduced 66 and 78% for plants exposed to 1.0 and 3.0 mg/L, respectively. Photosynthetic efficiency measured in dark-adapted plants was reduced 34 and 60% at the same respective concentrations, whereas photosynthetic efficiency measured in light-adapted plants was reduced 76 and 92%, respectively. Simazine activity in solution was reduced 80% over 7 d. By day 7, Simazine (and/or an impurity) was distributed throughout the plant, but predominantly occurred in the leaves. Uptake of Simazine was correlated with water uptake throughout the 7 d. These results suggest that C. hybrida may be a good candidate for incorporation into a phytoremediation scheme for Simazine.
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Toxicity, Uptake, and Distribution of Simazine in Canna hybrida `King Humbert': Implications for Phytoremediation
Hortscience, 1998Co-Authors: Patrick C. Wilson, Ted Whitwell, Stephen J KlaineAbstract:This research focuses on the potential use of Canna hybrida `King Humbert' for removing Simazine from contaminated water generated at golf courses and ornamental nurseries. Because of Simazine's herbicidal activity, it is important for levels in solution not to exceed plant tolerance levels. Tolerance levels for C. hybrida were determined by dosing plants for 7 d with 0, 0.01, 0.03, 0.1, 0.3, 1.0, or 3.0 mg Simazine/L nutrient media. Measurements of 7-d fresh mass production and photosynthetic efficiency (Fv/Fm) were taken. Simazine uptake and distribution within the plant was determined by dosing plants with 2.03 mCi 14C-Simazine (0.243 mg/L) for 1, 3, 5, or 7 d. Plant tissues were analyzed by combustion and liquid scintillation counting. Fresh mass production was reduced 66% and 78% for plants exposed to 1.0 and 3.0 mg/L, respectively. Likewise, photosynthetic efficiency was reduced to 66% and 40% of the controls at the same respective concentrations. Plant uptake of Simazine accounted for 13%, 34%, 48%, and 65% of the original Simazine in the dosing solution after 1-, 3-, 5-, and 7-d exposure, respectively. This Simazine was distributed primarily between roots and leaves.
Michael Seeger - One of the best experts on this subject based on the ideXlab platform.
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Influence of microorganisms and leaching on Simazine attenuation in an agricultural soil.
Journal of Environmental Management, 2012Co-Authors: Verónica Morgante, Cecilia Flores, Ximena Fadic, Myriam González, Marcela Hernández, Francisco Cereceda-balic, Michael SeegerAbstract:Simazine is an s-triazine herbicide world widely used for the control of broadleaf weeds. The influence of leaching and microorganisms on Simazine attenuation in an agricultural soil long-term treated with this herbicide was studied. To elucidate the leaching potential of Simazine in this soil, undisturbed soil columns amended with Simazine were placed in a specially designed system and an artificial precipitation was simulated. To evaluate the Simazine removal by soil microorganisms, three soil microcosm sets were established: i) control soil; ii) soil subjected to gamma irradiation (γ-soil) and iii) γ-soil inoculated with the Simazine-degrading bacterium Pseudomonas sp. strain MHP41. The Simazine-degrading microorganisms in soil were estimated using an indicator for respiration combined with MPN enumeration. The Simazine removal in soil was monitored by GC-ECD and HPLC. In this agricultural soil the leaching of the applied Simazine was negligible. The gamma irradiation decreased in more than one order of magnitude the cultivable heterotrophic bacteria and reduced the Simazine-degrading microorganisms. Simazine was almost completely depleted (97%) in control soil by natural attenuation after 23 d, whereas in γ-soil only 70% of Simazine was removed. The addition of the Simazine-degrading strain MHP41 to γ-soil restored and upheld high stable Simazine catabolic microorganisms as well as increased the Simazine removal (87%). The results indicated that Simazine is subjected to microbial degradation with negligible leaching in this agricultural soil and pointed out the crucial role of native microbiota in the herbicide removal.
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Simazine application inhibits nitrification and changes the ammonia oxidizing bacterial communities in a fertilized agricultural soil
FEMS Microbiology Ecology, 2011Co-Authors: Marcela Hernández, Zhongjun Jia, Ralf Conrad, Michael SeegerAbstract:s-Triazine herbicides are widely used for weed control, and are persistent in soils. Nitrification is an essential process in the global nitrogen cycle in soil, and involves ammonia-oxidizing Bacteria (AOB) and ammonia-oxidizing Archaea (AOA). In this study, we evaluated the effect of the s-triazine herbicide Simazine on the nitrification and on the structure of ammonia-oxidizing microbial communities in a fertilized agricultural soil. The effect of Simazine on AOB and AOA were studied by PCR-amplification of amoA genes of nitrifying Bacteria and Archaea in soil microcosms and denaturing gradient gel electrophoresis (DGGE) analyses. Simazine [50 ?g g?1 dry weight soil (d.w.s)] completely inhibited the nitrification processes in the fertilized agricultural soil. The inhibition by Simazine of ammonia oxidation observed was similar to the reduction of ammonia oxidation by the nitrification inhibitor acetylene. The application of Simazine-affected AOB community DGGE patterns in the agricultural soil amended with ammonium, whereas no significant changes in the AOA community were observed. The DGGE analyses strongly suggest that Simazine inhibited Nitrosobacteria and specifically Nitrosospira species. In conclusion, our results suggest that the s-triazine herbicide not only inhibits the target susceptible plants but also inhibits the ammonia oxidation and the AOB in fertilized soils.
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Adsorption studies of the herbicide Simazine in agricultural soils of the Aconcagua valley, central Chile.
Chemosphere, 2008Co-Authors: Cecilia Flores, Verónica Morgante, Myriam González, Rodrigo Navia, Michael SeegerAbstract:Simazine is a s-triazine herbicide that has been applied worldwide for agriculture. This herbicide is the second most commonly detected pesticide in surface and groundwater in the United States, Europe and Australia. In this study, Simazine adsorption behaviour was studied in two agricultural soils of the Aconcagua valley, central Chile. The two studied soils were soil A (loam, 8.5% organic matter content) and soil B (clay-loam, 3.5% organic matter content). Three times higher Simazine adsorption capacity was observed in soil A (68.03 mg kg−1) compared to soil B (22.03 mg kg−1). The Simazine adsorption distribution coefficients (Kd) were 9.32 L kg−1 for soil A and 7.74 L kg−1 for soil B. The Simazine adsorption enthalpy in soil A was −21.0 kJ mol−1 while in soil B the adsorption enthalpy value was −11.5 kJ mol−1. These results indicate that Simazine adsorption process in these soils is exothermic, governing H bonds the adsorption process of Simazine in both the loam and clay-loam soils. These results and the potentiometric profiles of both soils, suggest that Simazine adsorption in soil A is mainly governed by Simazine–organic matter interactions and in soil B by Simazine–clay interactions. The understanding of Simazine sorption–desorption processes is essential to determine the pesticide fate and availability in soil for pest control, biodegradation, runoff and leaching.
Michele Pansini - One of the best experts on this subject based on the ideXlab platform.
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novel process to prepare magnetic metal ceramic nanocomposites from zeolite precursor and their use as adsorbent of agrochemicals from water
Journal of environmental chemical engineering, 2018Co-Authors: Michele Pansini, Filomena Sannino, Antonello Marocco, Paolo Maria Eugenio Icilio Allia, P Tiberto, Gabriele Barrera, Michelangelo Polisi, Edmondo Battista, Paolo A NettiAbstract:Abstract In this work the preparation of two samples of magnetic adsorbent from a zeolite precursor was described. This process implied N H 4 + and Fe2+ exchange of zeolite A and its subsequent thermal treatment at temperature 600–800 °C, under a reducing atmosphere. These two magnetic adsorbents, composed of Fe/Fe3O4 nanoparticles embedded in an amorphous silica-alumina ceramic phase, were fully characterized by determining their chemical composition, quantitative phase analysis, surface area, SEM and TEM analysis, pH of zero potential and magnetic properties. In particular, their Fe content was 0.2 or 4.8%, Fe3O4content 5.4 or 7.1% and the average dimension of nanoparticles was 1.82 or 11.13 nm. Then, the removal of the agrochemical Simazine from water was performed by using these two magnetic adsorbents. The investigated parameters were pH, time, solid/liquid ratio and initial Simazine concentration. The pH of maximum Simazine adsorption was 6.5 and 3.0 for the two adsorbents. At these pH values, Simazine adsorption occurred rapidly and massively even from very dilute Simazine solutions (Simazine concentration of about 0.25 μmole/L). Finally, a process of Simazine removal from waters based on repeated cycles of adsorbent addition to Simazine bearing water, followed by its easy magnetic separation, is proposed. This process allows bringing the final agrochemical concentration well below 0.05 mg/L, the maximum agrochemical concentration allowed by Italian laws in wastewaters. Simazine bearing exhausted adsorbents are regenerated by a (no more than) 5 min thermal treatment at 300 °C, which results in the decomposition of Simazine without damage of the adsorbent.
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Simazine removal from waters by adsorption on porous silicas tailored by sol gel technique
Microporous and Mesoporous Materials, 2013Co-Authors: Filomena Sannino, Silvia Ruocco, Antonello Marocco, Serena Esposito, Michele PansiniAbstract:Abstract Two porous silica samples were synthesized through the sol–gel technique and characterized in terms of surface area and pore size distribution. The ability of such samples in removing Simazine from polluted waters by adsorption was evaluated by investigating the main process parameters (pH, time, initial Simazine concentration and solid/liquid ratio). An iterative process of Simazine removal from waters by adsorption on the more suitable of the two silica samples is proposed, featuring: (i) final Simazine concentration well below 0.05 mg/dm3, the maximum concentration allowed by Italian laws in wastewaters; (ii) regeneration of the adsorbent by a few minutes thermal treatment at 500 °C, which results in the removal of Simazine without markedly damaging the adsorbent; (iii) thorough oxidation of Simazine by combustion.
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cyclic process of Simazine removal from waters by adsorption on zeolite h y and its regeneration by thermal treatment
Journal of Hazardous Materials, 2012Co-Authors: Filomena Sannino, Silvia Ruocco, Antonello Marocco, Serena Esposito, Michele PansiniAbstract:Removal of the agrochemical Simazine from polluted waters through adsorption by zeolite Y in its protonic form was studied. The investigated parameters were: pH, time, initial Simazine concentration and solid/liquid ratio. An iterative process of Simazine removal from waters is proposed, featuring: (i) final agrochemical concentration well below 0.05 mg/dm(3), the maximum concentration allowed by Italian laws in wastewaters; (ii) regeneration of the adsorbent by a few minutes thermal treatment in air at about 500°C, which results in the combustion of Simazine without damage of the adsorbent; (iii) destruction of the agrochemical compound by combustion.
Filomena Sannino - One of the best experts on this subject based on the ideXlab platform.
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novel process to prepare magnetic metal ceramic nanocomposites from zeolite precursor and their use as adsorbent of agrochemicals from water
Journal of environmental chemical engineering, 2018Co-Authors: Michele Pansini, Filomena Sannino, Antonello Marocco, Paolo Maria Eugenio Icilio Allia, P Tiberto, Gabriele Barrera, Michelangelo Polisi, Edmondo Battista, Paolo A NettiAbstract:Abstract In this work the preparation of two samples of magnetic adsorbent from a zeolite precursor was described. This process implied N H 4 + and Fe2+ exchange of zeolite A and its subsequent thermal treatment at temperature 600–800 °C, under a reducing atmosphere. These two magnetic adsorbents, composed of Fe/Fe3O4 nanoparticles embedded in an amorphous silica-alumina ceramic phase, were fully characterized by determining their chemical composition, quantitative phase analysis, surface area, SEM and TEM analysis, pH of zero potential and magnetic properties. In particular, their Fe content was 0.2 or 4.8%, Fe3O4content 5.4 or 7.1% and the average dimension of nanoparticles was 1.82 or 11.13 nm. Then, the removal of the agrochemical Simazine from water was performed by using these two magnetic adsorbents. The investigated parameters were pH, time, solid/liquid ratio and initial Simazine concentration. The pH of maximum Simazine adsorption was 6.5 and 3.0 for the two adsorbents. At these pH values, Simazine adsorption occurred rapidly and massively even from very dilute Simazine solutions (Simazine concentration of about 0.25 μmole/L). Finally, a process of Simazine removal from waters based on repeated cycles of adsorbent addition to Simazine bearing water, followed by its easy magnetic separation, is proposed. This process allows bringing the final agrochemical concentration well below 0.05 mg/L, the maximum agrochemical concentration allowed by Italian laws in wastewaters. Simazine bearing exhausted adsorbents are regenerated by a (no more than) 5 min thermal treatment at 300 °C, which results in the decomposition of Simazine without damage of the adsorbent.
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Simazine removal from waters by adsorption on porous silicas tailored by sol gel technique
Microporous and Mesoporous Materials, 2013Co-Authors: Filomena Sannino, Silvia Ruocco, Antonello Marocco, Serena Esposito, Michele PansiniAbstract:Abstract Two porous silica samples were synthesized through the sol–gel technique and characterized in terms of surface area and pore size distribution. The ability of such samples in removing Simazine from polluted waters by adsorption was evaluated by investigating the main process parameters (pH, time, initial Simazine concentration and solid/liquid ratio). An iterative process of Simazine removal from waters by adsorption on the more suitable of the two silica samples is proposed, featuring: (i) final Simazine concentration well below 0.05 mg/dm3, the maximum concentration allowed by Italian laws in wastewaters; (ii) regeneration of the adsorbent by a few minutes thermal treatment at 500 °C, which results in the removal of Simazine without markedly damaging the adsorbent; (iii) thorough oxidation of Simazine by combustion.
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cyclic process of Simazine removal from waters by adsorption on zeolite h y and its regeneration by thermal treatment
Journal of Hazardous Materials, 2012Co-Authors: Filomena Sannino, Silvia Ruocco, Antonello Marocco, Serena Esposito, Michele PansiniAbstract:Removal of the agrochemical Simazine from polluted waters through adsorption by zeolite Y in its protonic form was studied. The investigated parameters were: pH, time, initial Simazine concentration and solid/liquid ratio. An iterative process of Simazine removal from waters is proposed, featuring: (i) final agrochemical concentration well below 0.05 mg/dm(3), the maximum concentration allowed by Italian laws in wastewaters; (ii) regeneration of the adsorbent by a few minutes thermal treatment in air at about 500°C, which results in the combustion of Simazine without damage of the adsorbent; (iii) destruction of the agrochemical compound by combustion.
