Electrochemical antimony removal from accumulator acid: Results from removal trials in laboratory cells

• Published in: Journal of hazardous materials Vol. 196; pp. 59 - 65
• Main Authors: Bergmann, M.E. Henry, Koparal, A. Savas
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 30.11.2011; Elsevier
• Subjects: Accumulator acid; anion exchange; Anion Exchange Resins; Antimony; Antimony - isolation & purification; Antimony removal; Applied sciences; Chemical engineering; crystallization; Crystallization, leaching, miscellaneous separations; Electric Power Supplies - standards; Electrochemical deposition; Electrochemical Techniques; electrochemistry; Electrodes; electrolytes; energy; Environmental Pollutants - isolation & purification; Exact sciences and technology; graphene; Ion exchange; Membranes, Artificial; Models, Theoretical; neutralization; Pilot Projects; Pollution; Reactors; sulfuric acid; Sulfuric Acids - chemistry; temperature; Time Factors; Waste Disposal, Fluid - instrumentation; Waste Disposal, Fluid - methods; Electrochemical deposition; Antimony removal; Antimony; Accumulator acid; Energy consumption; Electrochemical method; Crystallization; Laboratory scale; Electrode material; Electrochemical reactor; Electrodes; Electrolyte; Current efficiency; Anion exchange membrane; Separator
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2011.08.073

► In non-divided cells, antimony did not deposit at cathode due to oxidation of Sb(III) at anode. ► Copper and graphite were found to be the most suitable electrode materials for antimony deposition. ► Sb species covering electrode lowers deposition efficiency with time. ► Thus, periodical renewal of cathode material is necessary. ► Calculated specific electroenergy consumption was relatively high. ► In contrast, absolute energy consumption was low due to small quantities of antimony removed. Regeneration of spent accumulator acid could be an alternative process for crystallization, neutralisation and disposal. Therefore, for the first time in a study of the possibilities of electrochemical removal of antimony and accumulator acid regeneration on a laboratory scale, two synthetic and several real systems containing sulfuric acid of concentrations ranging between 28% and 36%, and antimony species were tested. Discontinuous electrochemical reactors with anion exchange membranes were successfully used in these experiments, which were conducted at a temperature of 35 °C. Removal of antimony using cells that were not divided by a separator, however, was not possible. In selected experiments, by varying the electrode material, type of electrolyte, and cell current, the concentration of antimony could be reduced from the range of 5 ppm to 0.15 ppm. This resulted in current efficiencies between 0.00002% and 0.001%, and in specific electroenergy demands between 100 Wh L −1 and 2000 Wh L −1. In other experiments on substances with antimony contents up to 3500 mg L −1, the current efficiencies obtained were more than a thousandfold higher. In contrast to the formally high relative energy consumption parameters absolute demand parameters are relatively small and favour the electrochemical method in small scale application. Besides plate electrodes, 3D-cathodes were used. Copper- and graphite cathodes produced the best results.