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77 BINDING CHARACTERISTICS OF HAZARDOUS ORGANIC SUBSTANCES TO CLAY SOILS G.A. Selvakumar, Graduate Assistant A.M. Rodrigo, Graduate Research Assistant P. Chan, Professor Civil and Environmental Engineering Department New Jersey Institute of Technology Newark, New Jersey 07102 INTRODUCTION Hazardous and toxic pollutants have been found in groundwater as a result of accidental spills, leaks, and intentional disposal from industrial and municipal waste disposal systems. As a result, the ground water contamination is at an alarming state and poses a health hazard. The U.S. Environmental Protection Agency has published the priority pollutant list,1 consisting of organic contaminants in conjunction with stipulated stringent regulations. The disposed liquid organic contaminants may percolate through the vadose zone and reach the water bearing aquifers. During the migration of contaminants towards the water bearing aquifers, the contaminants are constantly in contact with the soil. However, the fate of these contaminants is dependent upon chemical and biological reactions, including sorption kinetics. Certain chemicals that are hydrophobic and non-reactive in nature cause more affinity to solid particles than that of water. In the case of clay soils, the negative surface charges tend to bind dipolar organic compounds to form a diffuse electrical double layer. Hence, the degree to which the liquid organic contaminants are bound to the clay particles is one of the key factors which controls the contaminant transport. Thus, the rate, capacity and strength of sorption must be included in determining the fate of the contaminants in the groundwater system. A research project to identify and quantify the important factors influencing the binding of toxic and hazardous organic compounds to clay soils has been initiated at New Jersey Institute of Technology. Results of the batch study on illite with phenol, chlorophenol and chlorobenzene are presented in this paper. LITERATURE REVIEW The sorption of chlorinated hydrocarbon pesticides onto clay minerals was studied by Huang and Cheng.2 They found that there are varying amounts of sorption capacity in clay minerals, which depend upon the type of clay and pesticides. They also pointed out that desorption could occur if the pesticides coated soil particles are subjected to washing. This can act as a source of supply of toxic compounds into the groundwater system. Because of the sorption capacity of clays, a number of investigators have attempted to use clays and clay mixtures in attenuating heavy metals and other pollutants from the waste effluents before their ultimate disposal.3 Weber4 identifies two primary driving forces for adsorption. The first involves the degree of solubility of the dissolved substance, while the second involves the affinity of the solute for the solids. In the first case, a hydrophobic substance is literally driven from the liquid phase to the solid phase where adsorption occurs. Then a process of exchange adsorption occurs, in which ions of a substance accumulate at the surface of the solid due to electrostatic attraction. Therefore, the smaller the particles, the greater the specific surface area and hence the greater the sorption capacity. Hurle and Freed5 predicted that adsorption decreases and mobility increases as the solubility of solute in the solvent increases, i.e., the hydrophobic nature of sorbants results in more adsorption by clay soils. Recently, Uchrin and Katz6 studied the sorption characteristics of Lindane to New Jersey coastal plain aquifer soils which is predominantly sand. They identified two components of adsorption as reversible and resistant. A considerable discussion on the sorption process, including reversibility and 775
Object Description
Purdue Identification Number | ETRIWC198777 |
Title | Binding characteristics of hazardous organic substances to clay soils |
Author |
Selvakumar, G. A. Rodrigo, A. Mahendra Chan, P. |
Date of Original | 1987 |
Conference Title | Proceedings of the 42nd Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://e-archives.lib.purdue.edu/u?/engext,38818 |
Extent of Original | p. 775-780 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital object copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Date Digitized | 2009-08-03 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 775 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Transcript | 77 BINDING CHARACTERISTICS OF HAZARDOUS ORGANIC SUBSTANCES TO CLAY SOILS G.A. Selvakumar, Graduate Assistant A.M. Rodrigo, Graduate Research Assistant P. Chan, Professor Civil and Environmental Engineering Department New Jersey Institute of Technology Newark, New Jersey 07102 INTRODUCTION Hazardous and toxic pollutants have been found in groundwater as a result of accidental spills, leaks, and intentional disposal from industrial and municipal waste disposal systems. As a result, the ground water contamination is at an alarming state and poses a health hazard. The U.S. Environmental Protection Agency has published the priority pollutant list,1 consisting of organic contaminants in conjunction with stipulated stringent regulations. The disposed liquid organic contaminants may percolate through the vadose zone and reach the water bearing aquifers. During the migration of contaminants towards the water bearing aquifers, the contaminants are constantly in contact with the soil. However, the fate of these contaminants is dependent upon chemical and biological reactions, including sorption kinetics. Certain chemicals that are hydrophobic and non-reactive in nature cause more affinity to solid particles than that of water. In the case of clay soils, the negative surface charges tend to bind dipolar organic compounds to form a diffuse electrical double layer. Hence, the degree to which the liquid organic contaminants are bound to the clay particles is one of the key factors which controls the contaminant transport. Thus, the rate, capacity and strength of sorption must be included in determining the fate of the contaminants in the groundwater system. A research project to identify and quantify the important factors influencing the binding of toxic and hazardous organic compounds to clay soils has been initiated at New Jersey Institute of Technology. Results of the batch study on illite with phenol, chlorophenol and chlorobenzene are presented in this paper. LITERATURE REVIEW The sorption of chlorinated hydrocarbon pesticides onto clay minerals was studied by Huang and Cheng.2 They found that there are varying amounts of sorption capacity in clay minerals, which depend upon the type of clay and pesticides. They also pointed out that desorption could occur if the pesticides coated soil particles are subjected to washing. This can act as a source of supply of toxic compounds into the groundwater system. Because of the sorption capacity of clays, a number of investigators have attempted to use clays and clay mixtures in attenuating heavy metals and other pollutants from the waste effluents before their ultimate disposal.3 Weber4 identifies two primary driving forces for adsorption. The first involves the degree of solubility of the dissolved substance, while the second involves the affinity of the solute for the solids. In the first case, a hydrophobic substance is literally driven from the liquid phase to the solid phase where adsorption occurs. Then a process of exchange adsorption occurs, in which ions of a substance accumulate at the surface of the solid due to electrostatic attraction. Therefore, the smaller the particles, the greater the specific surface area and hence the greater the sorption capacity. Hurle and Freed5 predicted that adsorption decreases and mobility increases as the solubility of solute in the solvent increases, i.e., the hydrophobic nature of sorbants results in more adsorption by clay soils. Recently, Uchrin and Katz6 studied the sorption characteristics of Lindane to New Jersey coastal plain aquifer soils which is predominantly sand. They identified two components of adsorption as reversible and resistant. A considerable discussion on the sorption process, including reversibility and 775 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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