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https://hdl.handle.net/2142/71591
Description
Title
Disposal Methods for Diluted Herbicide Rinsates
Author(s)
Cho, Hyung-Yul
Issue Date
1983
Department of Study
Agronomy
Discipline
Agronomy
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Agronomy
Abstract
The purpose of this study was to develop a new disposal method for diluted herbicide rinsates. The thirteen herbicides used in this experiment were: atrazine cyanazine, simazine, metribuzin, linuron, oryzalin, trifluralin, fluchloralin, butylate, alachlor, metolachlor, 2,4-D DMA {dimethyl amine salt}, chloramben (ammonium salt). These compounds are the principal herbicides used in Illinois soybean and corn fields.
Simulated herbicide rinsates were prepared at the recommended rate of application in water alone or water/liquid nitrogen fertilizer combinations. These solutions were then diluted 5, 20 or 40 times with appropriate solution. The treatment process in the experiment was either destabilization-aggregation (coagulation and flocculation) of herbicide colloidal suspensions by adding calcium hydroxide and ferrous sulfate or crystallization-precipitation of ionized herbicide active ingredients by lowering pH below the pKa value. The water soluble portion of the herbicide active ingredient was removed from the supernatant with powdered activated carbon. The amount of herbicide remaining in the supernatant was almost equal to the water solubility of the standard compound, unless the compound was decomposed or dissociated under high pH conditions. Since the zeta-potential of wettable powder is reduced by specific gravity, destabilization-aggregation of colloidal suspensions of wettable powder could be achieved easier than that of emulsifier formulated herbicides. The destabilization-aggregation of colloidal suspensions of the emulsified mixtures required addition of both calcium hydroxide and ferrous sulfate.
The destabilization-aggregation of colloidal suspensions for 5, 20 or 40 times diluted rinsates generally required proportionally less electrolyte and the concentration of active ingredient in the supernatant was usually lower than that of the analytically pure compound. Rinsates prepared in liquid nitrogen fertilizer required less electrolyte than those prepared in water only.
After sedimentation of the colloidal suspension from the rinsate, powdered activated carbon was added to remove the herbicides in the supernatant. The removal rate of herbicide by powdered activated carbon varied according to various parameters. In general, 0.3 to 0.5 g of water soluble herbicide was adsorbed on 1 g of powdered activated carbon.
On the basis of these results, a disposal method for diluted herbicide rinsate is proposed with two solvent systems (water or liquid nitrogen fertilizer) and thirteen herbicides.
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