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37 REMOVAL OF HYDROPHOBIC ORGANIC COMPOUNDS FROM WASTES CONTAINING NATURAL ORGANIC AND INORGANIC MATTER Ahmad I. Jamrah, Assistant Professor Department of Civil Engineering and Construction Bradley University Peoria, Illinois 61625 Steven K. Dentel, Associate Professor Department of Civil Engineering University of Delaware Newark, Delaware 19716 INTRODUCTION Traditional activated carbon adsorption processes1,2 for the removal of the organic pollutants are often impaired due to substantial adsorptive interference by the NOM. It has been documented3-5 that severe reductions in the adsorption capacity of activated carbon for the targeted micropollutants occur as a result of this interference. Further, these interference effects are cumulative over time. Recent research has suggested that chemically modified clays represent a promising new group of adsorbents that may circumvent the non-selectivity drawbacks associated with activated carbon. The chemical modification utilizes charge and structural characteristics of clays to allow synthesis of an adsorbent capable of preferential uptake of contaminants. Clays generally possess a negative charge due to isomorphic substitution in the tetrahedral and octahedral layers of the mineral. In the case of montmorillonite, the tetravalent Si in the tetrahedral sheet may be partly replaced by trivalent Al, while there might be a replacement of the trivalent Al in the octahedral sheet by divalent Mg without complete filling of the third vacant octahedral position. The surplus of the negative charge is usually compensated for by the adsorption of cations such as Na+ and Ca + 2. In aqueous environments, these cations can be exchanged easily due to their tendency to form soluble hydroxides, which, combined with the presence of Si-O groups at the mineral surface, grants hydrophilic properties to the clay surface. Poor adsorption of hydrophobic organic compounds results, due to the competition of the more polar water molecules for adsorption sites at the mineral surface.6 MATERIALS AND METHODS ADSORPTIVES Tannic acid This material was used in the experiments as a laboratory surrogate for natural organics present in natural waters which are competing adsorbates. The tannic acid used in the experiments was supplied by Sigma Chemical Company, and reported to have a mean molecular mass of 1700. The use of tannic acid in the experiments was favored because it contains both saccharide and aromatic acid components that are significant in surface waters.7,8 1,2,4-Trichlorobenzene (TCB) This is a synthetic organic compound and one of the EPA priority pollutants. Maximum Contaminant Level (MCL) and Maximum Contaminant Level Goal (MCLG) were set to 0.07 mg/L for TCB in the fourth phase of Safe Drinking Water Act regulations.9 TCB may be considered as representative of halogenated organic water pollutants and disinfection by-products that have been detected in groundwater'0 and in surface waters.3 49th Purdue Industrial Waste Conference Proceedings, 1994 Lewis Publishers, Chelsea, Michigan 48118. Printed in U.S.A. 337
Object Description
Purdue Identification Number | ETRIWC199437 |
Title | Removal of hydrophobic organic compounds from wastes containing natural organic and inorganic matter |
Author |
Jamrah, Ahmad, I. Dentel, Steven K. |
Date of Original | 1994 |
Conference Title | Proceedings of the 49th Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://e-archives.lib.purdue.edu/u?/engext,44602 |
Extent of Original | p. 337-342 |
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 | 2009-12-10 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 337 |
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 | 37 REMOVAL OF HYDROPHOBIC ORGANIC COMPOUNDS FROM WASTES CONTAINING NATURAL ORGANIC AND INORGANIC MATTER Ahmad I. Jamrah, Assistant Professor Department of Civil Engineering and Construction Bradley University Peoria, Illinois 61625 Steven K. Dentel, Associate Professor Department of Civil Engineering University of Delaware Newark, Delaware 19716 INTRODUCTION Traditional activated carbon adsorption processes1,2 for the removal of the organic pollutants are often impaired due to substantial adsorptive interference by the NOM. It has been documented3-5 that severe reductions in the adsorption capacity of activated carbon for the targeted micropollutants occur as a result of this interference. Further, these interference effects are cumulative over time. Recent research has suggested that chemically modified clays represent a promising new group of adsorbents that may circumvent the non-selectivity drawbacks associated with activated carbon. The chemical modification utilizes charge and structural characteristics of clays to allow synthesis of an adsorbent capable of preferential uptake of contaminants. Clays generally possess a negative charge due to isomorphic substitution in the tetrahedral and octahedral layers of the mineral. In the case of montmorillonite, the tetravalent Si in the tetrahedral sheet may be partly replaced by trivalent Al, while there might be a replacement of the trivalent Al in the octahedral sheet by divalent Mg without complete filling of the third vacant octahedral position. The surplus of the negative charge is usually compensated for by the adsorption of cations such as Na+ and Ca + 2. In aqueous environments, these cations can be exchanged easily due to their tendency to form soluble hydroxides, which, combined with the presence of Si-O groups at the mineral surface, grants hydrophilic properties to the clay surface. Poor adsorption of hydrophobic organic compounds results, due to the competition of the more polar water molecules for adsorption sites at the mineral surface.6 MATERIALS AND METHODS ADSORPTIVES Tannic acid This material was used in the experiments as a laboratory surrogate for natural organics present in natural waters which are competing adsorbates. The tannic acid used in the experiments was supplied by Sigma Chemical Company, and reported to have a mean molecular mass of 1700. The use of tannic acid in the experiments was favored because it contains both saccharide and aromatic acid components that are significant in surface waters.7,8 1,2,4-Trichlorobenzene (TCB) This is a synthetic organic compound and one of the EPA priority pollutants. Maximum Contaminant Level (MCL) and Maximum Contaminant Level Goal (MCLG) were set to 0.07 mg/L for TCB in the fourth phase of Safe Drinking Water Act regulations.9 TCB may be considered as representative of halogenated organic water pollutants and disinfection by-products that have been detected in groundwater'0 and in surface waters.3 49th Purdue Industrial Waste Conference Proceedings, 1994 Lewis Publishers, Chelsea, Michigan 48118. Printed in U.S.A. 337 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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