The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
Bernard Legube - One of the best experts on this subject based on the ideXlab platform.
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Effect of the adsorbate (Bromacil) equilibrium concentration in water on its adsorption on powdered activated carbon. Part 3: Competition with natural organic matter.
Journal of Hazardous Materials, 2010Co-Authors: Fadi Al Mardini, Bernard LegubeAbstract:This study (part 3) was carried out to investigate the effect of the natural organic matter (NOM) concentration on Bromacil (pesticide) adsorption on powdered activated carbon (PAC) in the same experimental conditions as in our previous studies (parts 1 and 2). Our previous findings showed that Bromacil adsorption in buffered pure water (pH 7.8) occurred at two types of site. In the presence of NOM (three kinds), we noted a significant reduction in Bromacil adsorption capacities due to the competitive effects exerted by NOM. Highly reactive sites (or pores) in PAC appeared to be blocked by NOM adsorption, as demonstrated by the application of a pseudo-single solute isotherm and of the simplified ideal adsorbed solution theory (IAST), regardless of the initial Bromacil and NOM concentrations. The competing effect of low-molecular weight NOM was found to be greater than the competing effect of high-molecular weight NOM. The pseudo-second order surface-reaction model fitted Bromacil adsorption particularly well, even in the presence of NOM. However, the adsorption-kinetic constant values were found to be independent of the aqueous equilibrium concentration of the target compound, contrary to that observed in pure water. The kinetic data thus confirmed that high reactivity PAC sites were blocked by NOM adsorption. A practical approach concluded this work.
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Effect of the adsorbate (Bromacil) equilibrium concentration in water on its adsorption on powdered activated carbon. Part 1. Equilibrium parameters
Journal of Hazardous Materials, 2009Co-Authors: Fadi Al Mardini, Bernard LegubeAbstract:Abstract The application of several monosolute equilibrium models has previously shown that Bromacil adsorption on SA-UF (Norit) powdered activated carbon (PAC) is probably effective on two types of sites. High reactivity sites were found to be 10–20 less present in a carbon surface than lower reactivity sites, according to the q m values calculated by isotherm models. The aims of this work were trying, primarily, to identify the kinetic-determinant stage of the sorption of Bromacil at a wide range of initial pesticide concentrations (∼5 to ∼500 μg L −1 at pH 7.8), and secondly, to specify the rate constants and other useful design parameters for the application in water treatment. It was therefore not possible to specify a priori whether the diffusion or surface reaction is the key step. It shows that many of the tested models which describe the stage of distribution or the surface reaction are correctly applied. However, the diffusivity values ( D and D 0 ) were found to be constant only constants for some specific experimental concentrations. The HSDM model of surface diffusion in pores was also applied but the values of the diffusion coefficient of surface ( D s ) were widely scattered and reduce significantly with the initial concentration or the equilibrium concentration in Bromacil. The model of surface reaction of pseudo-second order fitted particularly well and led to constant values which are independent of the equilibrium concentration, except for the low concentrations where the constants become significantly more important. This last observation confirms perfectly the hypothesis based on two types of sites as concluded by the equilibrium data (part 1).
Fadi Al Mardini - One of the best experts on this subject based on the ideXlab platform.
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Effect of the adsorbate (Bromacil) equilibrium concentration in water on its adsorption on powdered activated carbon. Part 3: Competition with natural organic matter.
Journal of Hazardous Materials, 2010Co-Authors: Fadi Al Mardini, Bernard LegubeAbstract:This study (part 3) was carried out to investigate the effect of the natural organic matter (NOM) concentration on Bromacil (pesticide) adsorption on powdered activated carbon (PAC) in the same experimental conditions as in our previous studies (parts 1 and 2). Our previous findings showed that Bromacil adsorption in buffered pure water (pH 7.8) occurred at two types of site. In the presence of NOM (three kinds), we noted a significant reduction in Bromacil adsorption capacities due to the competitive effects exerted by NOM. Highly reactive sites (or pores) in PAC appeared to be blocked by NOM adsorption, as demonstrated by the application of a pseudo-single solute isotherm and of the simplified ideal adsorbed solution theory (IAST), regardless of the initial Bromacil and NOM concentrations. The competing effect of low-molecular weight NOM was found to be greater than the competing effect of high-molecular weight NOM. The pseudo-second order surface-reaction model fitted Bromacil adsorption particularly well, even in the presence of NOM. However, the adsorption-kinetic constant values were found to be independent of the aqueous equilibrium concentration of the target compound, contrary to that observed in pure water. The kinetic data thus confirmed that high reactivity PAC sites were blocked by NOM adsorption. A practical approach concluded this work.
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Effect of the adsorbate (Bromacil) equilibrium concentration in water on its adsorption on powdered activated carbon. Part 1. Equilibrium parameters
Journal of Hazardous Materials, 2009Co-Authors: Fadi Al Mardini, Bernard LegubeAbstract:Abstract The application of several monosolute equilibrium models has previously shown that Bromacil adsorption on SA-UF (Norit) powdered activated carbon (PAC) is probably effective on two types of sites. High reactivity sites were found to be 10–20 less present in a carbon surface than lower reactivity sites, according to the q m values calculated by isotherm models. The aims of this work were trying, primarily, to identify the kinetic-determinant stage of the sorption of Bromacil at a wide range of initial pesticide concentrations (∼5 to ∼500 μg L −1 at pH 7.8), and secondly, to specify the rate constants and other useful design parameters for the application in water treatment. It was therefore not possible to specify a priori whether the diffusion or surface reaction is the key step. It shows that many of the tested models which describe the stage of distribution or the surface reaction are correctly applied. However, the diffusivity values ( D and D 0 ) were found to be constant only constants for some specific experimental concentrations. The HSDM model of surface diffusion in pores was also applied but the values of the diffusion coefficient of surface ( D s ) were widely scattered and reduce significantly with the initial concentration or the equilibrium concentration in Bromacil. The model of surface reaction of pseudo-second order fitted particularly well and led to constant values which are independent of the equilibrium concentration, except for the low concentrations where the constants become significantly more important. This last observation confirms perfectly the hypothesis based on two types of sites as concluded by the equilibrium data (part 1).
D R Lauren - One of the best experts on this subject based on the ideXlab platform.
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determination of Bromacil in groundwater and in high organic matter soils
Journal of Agricultural and Food Chemistry, 1995Co-Authors: Trevor K James, D R LaurenAbstract:Solid phase extraction (SPE) technology for the determination of Bromacil in environmental water samples was compared with traditional liquid/liquid partitioning methods. SPE was found to be more cost effective and safer due to the use of smaller volumes of solvent. Detection of less than 0.05 μg/L of Bromacil was possible with the analysis of large (1 L) samples. A practical and beneficial enhancement of the existing methods for soil extraction with aqueous sodium hydroxide, is described. Holding the extraction mixture at a temperature of 30 or 50 o C for 18 h increased the recovery of Bromacil in nine of 12 soils studied, and minimized the use of solvents. The method was effective on high organic matter soils. HPLC was used for analysis of both water and soil extracts
Nanthi Bolan - One of the best experts on this subject based on the ideXlab platform.
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degradation of atrazine and Bromacil in two forestry waste products
Scientific Reports, 2021Co-Authors: T K James, Hossein Ghanizadeh, K C Harrington, Nanthi BolanAbstract:The persistence and degradation of two common herbicides, atrazine and Bromacil in two organic media, wood pulp and sawdust were compared with two soils. The hypothesis tested was that herbicide degradation will be faster in high organic matter media compared to soil. Degradation of two herbicides was carried out in four different temperature regimes and in sterilised media. The degradation half-life (t½) was determined under above-mentioned conditions then compared to degradation in soil. The degradation as quantified by t½ of the herbicides was generally longer in both organic media. Although microbial degradation was an important factor in the mineralisation of these herbicides, overall, the pH of the media had a more profound effect on the desorption and subsequent degradation rate than the organic carbon content. The results of this study revealed that the hypothesis was only partially correct as organic matter content per se did not strongly relate to degradation rates which were mainly governed by pH and microbial activity.
Trevor K James - One of the best experts on this subject based on the ideXlab platform.
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determination of Bromacil in groundwater and in high organic matter soils
Journal of Agricultural and Food Chemistry, 1995Co-Authors: Trevor K James, D R LaurenAbstract:Solid phase extraction (SPE) technology for the determination of Bromacil in environmental water samples was compared with traditional liquid/liquid partitioning methods. SPE was found to be more cost effective and safer due to the use of smaller volumes of solvent. Detection of less than 0.05 μg/L of Bromacil was possible with the analysis of large (1 L) samples. A practical and beneficial enhancement of the existing methods for soil extraction with aqueous sodium hydroxide, is described. Holding the extraction mixture at a temperature of 30 or 50 o C for 18 h increased the recovery of Bromacil in nine of 12 soils studied, and minimized the use of solvents. The method was effective on high organic matter soils. HPLC was used for analysis of both water and soil extracts
