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פותח על ידי קלירמאש פתרונות בע"מ -
Sorption and hydrolysis of environmental pollutants by organoclays
Year:
2006
Source of publication :
ACS Symposium Series
Authors :
גרסטל, זאב
;
.
מינגלגרין, אורי
;
.
Volume :
940
Co-Authors:
Gerstl, Z., Institute of Soil, Water and Environmental Sciences, Volcani Center, ARO, P.O. Box 6, Bet Dagan 50250, Israel
Groisman, L., Research Laboratory of Water Quality, Ministry of Health, P.O. Box 8255, Tel-Aviv 61080, Israel
Rav-Acha, C., Research Laboratory of Water Quality, Ministry of Health, P.O. Box 8255, Tel-Aviv 61080, Israel
Mingelgrin, U., Institute of Soil, Water and Environmental Sciences, Volcani Center, ARO, P.O. Box 6, Bet Dagan 50250, Israel
Facilitators :
From page:
67
To page:
84
(
Total pages:
18
)
Abstract:
Organoclays are clays whose surfaces are rendered organophilic by the exchange of inorganic cations with various organic cations. The sorption of six compounds with a range of log Kow values from 2.5 to 6 was studied on shortand long-chain organoclays. Compounds with low or medium hydrophobicities were more strongly sorbed on the short-chain organoclay, whereas the more hydrophobic compounds were better sorbed on the long-chain organoclay. It was found that both types of organoclays were able to remove organic pollutants from the effluent of a pesticide producing plant, but solute uptake by short-chain organoclays was strongly depressed by competition, while long-chain organoclays were only slightly affected by the presence of competing solutes in the industrial wastewater. A bifunctional organoclay that is able to sorb organophosphate pesticides, as well as to catalyze their hydrolysis, has been prepared. The detoxifying capacity of this organoclay for methyl parathion and tetrachlorvinphos, was demonstrated. The half-life for the hydrolysis of the investigated pesticides in the presence of the bifunctional organoclay is about 12 times less than for their spontaneous hydrolysis. The mechanism of the catalytic hydrolysis of methyl parathion by the bifunctional organoclay was studied by following the effect of replacing H2O with D2O, by replacing the primary amino headgroup of the organic cation in the bifunctional clay by a tertiary amino group and by a detailed mathematical analysis of the reaction kinetics. An isomer of MP was formed in the presence of the bifunctional organoclay, initially increasing in concentration and then disappearing, the effect of the isotope replacement was minimal and the tertiary amine substitution increased the rate of MP hydrolysis. Based on these findings we propose a mechanism in which hydrolysis of MP proceeds both via a direct route (specific base hydrolysis) and via the formation of the isomer which then undergoes specific base hydrolysis more rapidly than the parent MP. The relative importance of each pathway is a function of pH with the direct hydrolysis of MP predominant at higher pH values (pH>10) and the isomer pathway predominating at intermediate pH values (pH-8-10). © 2006 American Chemical Society.
Note:
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DOI :
Article number:
Affiliations:
Database:
סקופוס
Publication Type:
מאמר מתוך כינוס
;
.
Language:
אנגלית
Editors' remarks:
ID:
29761
Last updated date:
02/03/2022 17:27
Creation date:
17/04/2018 00:49
Scientific Publication
Sorption and hydrolysis of environmental pollutants by organoclays
940
Gerstl, Z., Institute of Soil, Water and Environmental Sciences, Volcani Center, ARO, P.O. Box 6, Bet Dagan 50250, Israel
Groisman, L., Research Laboratory of Water Quality, Ministry of Health, P.O. Box 8255, Tel-Aviv 61080, Israel
Rav-Acha, C., Research Laboratory of Water Quality, Ministry of Health, P.O. Box 8255, Tel-Aviv 61080, Israel
Mingelgrin, U., Institute of Soil, Water and Environmental Sciences, Volcani Center, ARO, P.O. Box 6, Bet Dagan 50250, Israel
Sorption and hydrolysis of environmental pollutants by organoclays
Organoclays are clays whose surfaces are rendered organophilic by the exchange of inorganic cations with various organic cations. The sorption of six compounds with a range of log Kow values from 2.5 to 6 was studied on shortand long-chain organoclays. Compounds with low or medium hydrophobicities were more strongly sorbed on the short-chain organoclay, whereas the more hydrophobic compounds were better sorbed on the long-chain organoclay. It was found that both types of organoclays were able to remove organic pollutants from the effluent of a pesticide producing plant, but solute uptake by short-chain organoclays was strongly depressed by competition, while long-chain organoclays were only slightly affected by the presence of competing solutes in the industrial wastewater. A bifunctional organoclay that is able to sorb organophosphate pesticides, as well as to catalyze their hydrolysis, has been prepared. The detoxifying capacity of this organoclay for methyl parathion and tetrachlorvinphos, was demonstrated. The half-life for the hydrolysis of the investigated pesticides in the presence of the bifunctional organoclay is about 12 times less than for their spontaneous hydrolysis. The mechanism of the catalytic hydrolysis of methyl parathion by the bifunctional organoclay was studied by following the effect of replacing H2O with D2O, by replacing the primary amino headgroup of the organic cation in the bifunctional clay by a tertiary amino group and by a detailed mathematical analysis of the reaction kinetics. An isomer of MP was formed in the presence of the bifunctional organoclay, initially increasing in concentration and then disappearing, the effect of the isotope replacement was minimal and the tertiary amine substitution increased the rate of MP hydrolysis. Based on these findings we propose a mechanism in which hydrolysis of MP proceeds both via a direct route (specific base hydrolysis) and via the formation of the isomer which then undergoes specific base hydrolysis more rapidly than the parent MP. The relative importance of each pathway is a function of pH with the direct hydrolysis of MP predominant at higher pH values (pH>10) and the isomer pathway predominating at intermediate pH values (pH-8-10). © 2006 American Chemical Society.
Scientific Publication
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