Spent nickel-cadmium batteries secondary resource
End-of-life nickel-cadmium batteries, represented here by prepared active electrode powder from dismantled cells. The accepted experiment concerns the cathode fraction, not an intact battery or a pooled whole-cell metal inventory. This Ni/Cd secondary-cell resource is distinct from nickel-metal-hydride batteries, mixed alkaline/zinc-carbon primary cells, button-cell powder and lithium-ion black mass. Constituent-element criticality is not inherited.
Microbial & Biochemical Mechanisms (1)
Acidophilic culture-associated cathode leaching with ferric comparison
bioleaching
Microbial
Associated Organisms:
Acidithiobacillus ferrooxidans (NCBITaxon:920)
A culture-containing acidic leach mobilized Cd and part of the Ni from prepared spent NiCd cathode material. A separate abiotic ferric-sulfate treatment produced comparable reported extraction. The observations support culture-associated leaching but do not establish a microbial advantage, a requirement for live-cell contact, or an independently isolated ferric-oxidation mechanism. Dissolved metals were measured; an isolated Ni or Cd product was not demonstrated.
Experimental Context & Analytical Limits:
Methods 2.1–2.4, pp.1460–1461: batteries were opened, rolled electrodes separated, and cathode/anode active powders removed from metal grids, ground and sieved below 40 micrometres. Cathode assays were 6.5% Cd and 47.1% Ni; separately reported anode assays were 38% Cd and 22.2% Ni. Results 3.1.2 assigns the plotted experiment to cathode material; anode composition is not an extraction denominator for that arm. The stated setup used 2 g powder and 200 mL medium in 250-mL flasks, initial pH 1.5 adjusted using 10 M H2SO4 or 10% NaOH, with experiments in triplicate and sampling on days 1, 3, 7, 10, 13, 21 and 28. Five-mL leachate samples were filtered and analyzed by atomic absorption. Methods assigns a pure A. ferrooxidans culture in 9K medium and 5 mL pure-culture inoculum; culture provenance is Smolnik acid mine drainage through the Slovak Academy of Sciences, with no strain accession or experimental-stock sequence authentication. Figure 2 instead calls the biotic treatment a mixture with A. thiooxidans. That unresolved caption/Methods conflict prevents a definitive culture-composition or species-specific causal conclusion. Dilute sulfuric-acid and ferric-sulfate abiotic treatments were included. The latter is described as 44.63 g/L reagent, but its printed hydrated-salt formula is malformed; no elemental-Fe concentration is inferred. Leaching temperature, agitation and a complete sampling-volume correction are not specified for this arm.
Methods 2.1–2.4, pp.1460–1461: batteries were opened, rolled electrodes separated, and cathode/anode active powders removed from metal grids, ground and sieved below 40 micrometres. Cathode assays were 6.5% Cd and 47.1% Ni; separately reported anode assays were 38% Cd and 22.2% Ni. Results 3.1.2 assigns the plotted experiment to cathode material; anode composition is not an extraction denominator for that arm. The stated setup used 2 g powder and 200 mL medium in 250-mL flasks, initial pH 1.5 adjusted using 10 M H2SO4 or 10% NaOH, with experiments in triplicate and sampling on days 1, 3, 7, 10, 13, 21 and 28. Five-mL leachate samples were filtered and analyzed by atomic absorption. Methods assigns a pure A. ferrooxidans culture in 9K medium and 5 mL pure-culture inoculum; culture provenance is Smolnik acid mine drainage through the Slovak Academy of Sciences, with no strain accession or experimental-stock sequence authentication. Figure 2 instead calls the biotic treatment a mixture with A. thiooxidans. That unresolved caption/Methods conflict prevents a definitive culture-composition or species-specific causal conclusion. Dilute sulfuric-acid and ferric-sulfate abiotic treatments were included. The latter is described as 44.63 g/L reagent, but its printed hydrated-salt formula is malformed; no elemental-Fe concentration is inferred. Leaching temperature, agitation and a complete sampling-volume correction are not specified for this arm.
Curated Evidence Points:
Support
Source:
sedlakova2017
Results 3.1.2 and Figure 2A show Cd dissolution approaching the reported 100% level in both biotic and abiotic ferric treatments over the 28-day series, whereas the dilute-acid comparator is lower. This is a source-reported leaching efficiency for the prepared cathode fraction, not whole-cell or isolated-product recovery. The article does not give a complete efficiency equation, raw analytical series or a closed metal balance for independently reconstructing the percentage.
Partial
Source:
sedlakova2017
The abstract and Results 3.1.2 report 55% Ni extraction for both biotic and ferric treatments, but Figure 2B plots those series near 45–47%, below 50%. The prose and original graph are retained as conflicting source statements; neither is silently corrected or adopted as a harmonized yield. Both support partial Ni dissolution and similar biotic/ferric performance, rather than quantitative microbial superiority. Triplicates are stated, but Figure 2 has no displayed error bars or underlying replicate values.
Partial
Source:
sedlakova2017
The authors relate poor acid-only dissolution to neutralization and pH rising toward 7, and interpret ferric hydrolysis as sustaining acidity. Their oxidative and hydrolytic explanation and generalized equations are not separate measurements of phase-specific Ni oxidation or proof of an exclusive biological pathway. Figures 5 and 6 concern other-feed pH data and a proposed integrated recycling model respectively; they are not a NiCd pH time series or an operated closed-loop industrial plant. References 20–21 are earlier NiCd studies from overlapping authors; independence from those experiments is not established here, and their uninspected original measurements are not pooled with Figure 2.
Context_only
Source:
ncbi920
The live authority identifies A. ferrooxidans at species level. It does not resolve the primary paper's pure-versus-mixed-culture conflict, identify a strain, or prove that this organism caused the observed extraction beyond the chemical comparators.
Sources & References
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sedlakova2017: Sedlakova-Kadukova, Marcincakova, Mrazikova, Willner and Fornalczyk (2017). Closing the Loop: Key Role of Iron in Metal-Bearing Waste Recycling. Archives of Metallurgy and Materials 62(3):1459–1466. DOI 10.1515/amm-2017-0226. Complete eight-page primary PDF; Methods 2.1–2.4 and NiCd Results 3.1.2, especially original Figure 2 on p.1462. Other waste arms are not imported.
https://doi.org/10.1515/amm-2017-0226 (accessed 2026-10-12) -
ncbi920: NCBI Taxonomy 920: Acidithiobacillus ferrooxidans, current species identity; not authentication of the experimental culture.
https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=920&mode=Info (accessed 2026-10-12)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-12T14:02:02.669630+00:00 |
Codex (GPT-6; codex) | CREATE | Created the NiCd secondary-resource owner from complete original cathode-leaching evidence, preserving comparable abiotic ferric extraction, culture and numerical conflicts, and recovery/scale limits. |
Record source: data/records/spent-nickel-cadmium-batteries.yaml