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62 ELECTROCHEMICAL ABSTRACTION OF CADMIUM FROM DILUTE AQUEOUS SOLUTIONS USING THE ROTATING CATHODE CELL A. I. Sheikh, Research Assistant G. K. Anderson, Senior Lecturer Solid & Hazardous Waste Research Unit (SHWRU) L. M. Evison, Senior Lecturer Environmental Engineering Group. Department of Civil Engineering, University of Newcastle Upon Tyne, Newcastle Upon Tyne, NE1 7RU, England F. S. Holland, Consultant Chemist Electrochemical Techniques Limited (ETL) Stockport, Cheshire, England INTRODUCTION An EC-funded multidisciplinary consortium has successfully developed a new approach for the removal and recovery of aqueous cadmium, at low concentrations, from industrial effluents and other metal contaminated wastewaters. Biosorption, elution and electrolysis processes generate clean water and high quality metal for recycling and reuse. The electrochemical deposition of cadmium results in the production of metallic cadmium powder and a cadmium-depleted electrolyte for reuse as an eluant for cadmium-loaded biomass in the previous elution stage. This has been achieved using a Rotating Cathode Cell (RC Cell) which is a pilot-scale continuous flow cell, operating at very high mass transport rates, recovering the metal automatically outside the cell. The development of the process entailed conditioning the electrolyte with buffering and complexing agents. Batch and steady-state controlled potentiostatic electrolysis were shown to be conducive to fine powder production with selective electrolytes. The introduction of ever more stringent wastewater disposal guidelines is emphasizing the fact that improved processes for the recovery of cadmium and other hazardous metals from dilute solutions are required more and more urgently. Ion-exchange, solvent extraction, or precipitation processes are suitable for reducing the residual cadmium content of solutions down to very low final concentrations, but pose the risk of further producing a sludge hazard with alkaline precipitation. None of these processes are suitable for the recovery of cadmium as a metal from dilute solutions, and there is no doubt that it would be more economically and environmentally sound if metallic cadmium could be recovered from a waste stream. Electrochemical technology can contribute elegantly in many ways to a better relationship with the environment. The use of the electron as a reaction reagent ensures that the contaminants, which are often heavy metals, can be efficiently concentrated into a volume-reduced form amenable to subsequent disposal or recovery operations. This is achieved without the need to introduce chemical reagents which themselves add to the total volume of secondary waste generated. Electrochemical methods are also suitable for automation because of their simplicity and high sensitivity. Numerous laboratory cell designs have been suggested for the removal of metals via cathodic deposition but relatively few of these have reached pilot- or full-scale. The Rotating Cathode Cell (RC Cell) is one of the most successful geometries and may be classified as a moving, two- 51st Purdue Industrial Waste Conference Proceedings, 1996, Ann Arbor Press, Inc.. Chelsea. Michigan 48118. Printed in U.S.A. 613
Object Description
Purdue Identification Number | ETRIWC199662 |
Title | Electrochemical abstraction of cadmium from dilute aqueous solutions using the rotating cathode cell |
Author |
Sheikh, A. I. Anderson, G. K. Evison, L. M. Holland, F. S. |
Date of Original | 1996 |
Conference Title | Proceedings of the 51st Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://e-archives.lib.purdue.edu/u?/engext,46351 |
Extent of Original | p. 613-620 |
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 | 2009-10-27 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 613 |
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 | 62 ELECTROCHEMICAL ABSTRACTION OF CADMIUM FROM DILUTE AQUEOUS SOLUTIONS USING THE ROTATING CATHODE CELL A. I. Sheikh, Research Assistant G. K. Anderson, Senior Lecturer Solid & Hazardous Waste Research Unit (SHWRU) L. M. Evison, Senior Lecturer Environmental Engineering Group. Department of Civil Engineering, University of Newcastle Upon Tyne, Newcastle Upon Tyne, NE1 7RU, England F. S. Holland, Consultant Chemist Electrochemical Techniques Limited (ETL) Stockport, Cheshire, England INTRODUCTION An EC-funded multidisciplinary consortium has successfully developed a new approach for the removal and recovery of aqueous cadmium, at low concentrations, from industrial effluents and other metal contaminated wastewaters. Biosorption, elution and electrolysis processes generate clean water and high quality metal for recycling and reuse. The electrochemical deposition of cadmium results in the production of metallic cadmium powder and a cadmium-depleted electrolyte for reuse as an eluant for cadmium-loaded biomass in the previous elution stage. This has been achieved using a Rotating Cathode Cell (RC Cell) which is a pilot-scale continuous flow cell, operating at very high mass transport rates, recovering the metal automatically outside the cell. The development of the process entailed conditioning the electrolyte with buffering and complexing agents. Batch and steady-state controlled potentiostatic electrolysis were shown to be conducive to fine powder production with selective electrolytes. The introduction of ever more stringent wastewater disposal guidelines is emphasizing the fact that improved processes for the recovery of cadmium and other hazardous metals from dilute solutions are required more and more urgently. Ion-exchange, solvent extraction, or precipitation processes are suitable for reducing the residual cadmium content of solutions down to very low final concentrations, but pose the risk of further producing a sludge hazard with alkaline precipitation. None of these processes are suitable for the recovery of cadmium as a metal from dilute solutions, and there is no doubt that it would be more economically and environmentally sound if metallic cadmium could be recovered from a waste stream. Electrochemical technology can contribute elegantly in many ways to a better relationship with the environment. The use of the electron as a reaction reagent ensures that the contaminants, which are often heavy metals, can be efficiently concentrated into a volume-reduced form amenable to subsequent disposal or recovery operations. This is achieved without the need to introduce chemical reagents which themselves add to the total volume of secondary waste generated. Electrochemical methods are also suitable for automation because of their simplicity and high sensitivity. Numerous laboratory cell designs have been suggested for the removal of metals via cathodic deposition but relatively few of these have reached pilot- or full-scale. The Rotating Cathode Cell (RC Cell) is one of the most successful geometries and may be classified as a moving, two- 51st Purdue Industrial Waste Conference Proceedings, 1996, Ann Arbor Press, Inc.. Chelsea. Michigan 48118. Printed in U.S.A. 613 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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