The removal of heavy metal ions and organics from aqueous solutions using a reticulated vitreous carbon cathode cell
The removal of heavy metal ions and organics from aqueous solutions using a reticulated vitreous carbon cathode cell
Reticulated vitreous carbons (10, 60 and 100 ppi grades) have been further investigated as cathodes for the removal of low concentrations of both organics and heavy metal ions from effluents and process streams. The experiments use a batch recycle system including a membrane cell with the RVC cathode operating in the flow-by mode.
The Cu(II)/Cu, Pb(II)/Pb and Fe(CN)63-/Fe(CN)64- couples have all been used to characterise the mass transport regime within the cell as a function of electrolyte velocity. It is confirmed that the use of RVC cathodes can lead to a substantial (x 100) enhancement of the mass transport limited current compared to a flat plate cathode, and the increase in current is highest with 100 ppi material. Perhaps surprisingly, this increase in the mass transport limited current is shown to result mainly from the increase in surface area, and there is only a small change in the mass transfer coefficient. This result agrees with the conclusions from recent studies of metal foams and it appears that foam materials are rather poor turbulence promoters.
Pb(II) may be removed from solutions of chloride, nitrate, perchlorate, tetrafluoroborate and sulfate, pH 2, to levels << 1 ppm with reasonable current efficiencies. Only in chloride media, however, is the deposition of lead fully mass transport controlled. In nitrate, perchlorate, tetrafluoroborate solutions, the deposition is partially mass transport controlled and electrolyses take longer to deplete the Pb(II) in solution. In sulphate solutions, it is necessary to use an elevated temperature and a very negative potential to achieve a high rate of Pb(II) removal from solution; in these conditions, H2 evolution is the major reaction and the current efficiency is very poor. Potential scan and step experiments, as well as depletion electrolyses, are used to investigate the systems, and it is proposed that limitations in the rate of nucleation and growth of lead on the RVC surface is the main complication.
University of Southampton
Ponce de León Albarrán, Carlos
1994
Ponce de León Albarrán, Carlos
Ponce de León Albarrán, Carlos
(1994)
The removal of heavy metal ions and organics from aqueous solutions using a reticulated vitreous carbon cathode cell.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Reticulated vitreous carbons (10, 60 and 100 ppi grades) have been further investigated as cathodes for the removal of low concentrations of both organics and heavy metal ions from effluents and process streams. The experiments use a batch recycle system including a membrane cell with the RVC cathode operating in the flow-by mode.
The Cu(II)/Cu, Pb(II)/Pb and Fe(CN)63-/Fe(CN)64- couples have all been used to characterise the mass transport regime within the cell as a function of electrolyte velocity. It is confirmed that the use of RVC cathodes can lead to a substantial (x 100) enhancement of the mass transport limited current compared to a flat plate cathode, and the increase in current is highest with 100 ppi material. Perhaps surprisingly, this increase in the mass transport limited current is shown to result mainly from the increase in surface area, and there is only a small change in the mass transfer coefficient. This result agrees with the conclusions from recent studies of metal foams and it appears that foam materials are rather poor turbulence promoters.
Pb(II) may be removed from solutions of chloride, nitrate, perchlorate, tetrafluoroborate and sulfate, pH 2, to levels << 1 ppm with reasonable current efficiencies. Only in chloride media, however, is the deposition of lead fully mass transport controlled. In nitrate, perchlorate, tetrafluoroborate solutions, the deposition is partially mass transport controlled and electrolyses take longer to deplete the Pb(II) in solution. In sulphate solutions, it is necessary to use an elevated temperature and a very negative potential to achieve a high rate of Pb(II) removal from solution; in these conditions, H2 evolution is the major reaction and the current efficiency is very poor. Potential scan and step experiments, as well as depletion electrolyses, are used to investigate the systems, and it is proposed that limitations in the rate of nucleation and growth of lead on the RVC surface is the main complication.
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Published date: 1994
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Local EPrints ID: 458470
URI: http://eprints.soton.ac.uk/id/eprint/458470
PURE UUID: 01055adf-5228-44cd-af8d-3d4858817f66
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Date deposited: 04 Jul 2022 16:49
Last modified: 04 Jul 2022 16:49
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Author:
Carlos Ponce de León Albarrán
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