Duwiejuah et al. 2026 - Pineapple biochar for Cr and Ni leachate removal
Duwiejuah and colleagues prepared biochar from pineapple residues and tested it for simultaneous removal of chromium, nickel, and phenol from landfill leachate. This is a remediation paper, not pineapple occurrence evidence: the routeable heavy-metal facts are Cr and Ni concentrations in leachate and their removal by pineapple-residue biochar.
Key numbers
Initial landfill-leachate measurements were performed in triplicate before adsorption. The reported starting concentrations were Cr 2.10 mg/L, 2.15 mg/L, and 2.25 mg/L; Ni 0.67 mg/L, 0.68 mg/L, and 0.67 mg/L; and phenol 1.25 mg/L, 1.25 mg/L, and 1.30 mg/L.
Pineapple residues were collected from pineapple vendors in Aboabo Market in Tamale. The residue mix included stems, leaves, and other plant parts, was air-dried for 120 hours, and was pyrolyzed for 10 minutes at 350 +/- 5 C under limited oxygen in a locally engineered charring kiln.
Table 1 reports adsorption efficiency at 30 C:
| Contaminant | Biochar dose | 15 min | 30 min | 45 min |
|---|---|---|---|---|
| Cr | 0.50 g | 99.52% | 99.23% | 99.29% |
| Cr | 1.50 g | 99.54% | 99.35% | 99.70% |
| Cr | 3.00 g | 99.59% | 99.43% | 99.72% |
| Ni | 0.50 g | 99.13% | 98.96% | 98.72% |
| Ni | 1.50 g | 99.27% | 99.01% | 98.81% |
| Ni | 3.00 g | 99.40% | 99.13% | 98.94% |
| Phenol | 0.50 g | 22.76% | 23.62% | 25.20% |
| Phenol | 1.50 g | 37.01% | 37.01% | 40.16% |
| Phenol | 3.00 g | 48.82% | 50.24% | 54.88% |
Table 1 reports adsorption efficiency at 35 C:
| Contaminant | Biochar dose | 15 min | 30 min | 45 min |
|---|---|---|---|---|
| Cr | 0.50 g | 99.24% | 99.48% | 99.56% |
| Cr | 1.50 g | 99.56% | 99.26% | 99.59% |
| Cr | 3.00 g | 99.59% | 99.64% | 99.67% |
| Ni | 0.50 g | 99.07% | 98.76% | 99.30% |
| Ni | 1.50 g | 99.13% | 98.94% | 99.43% |
| Ni | 3.00 g | 99.27% | 98.99% | 99.55% |
| Phenol | 0.50 g | 37.01% | 41.73% | 38.58% |
| Phenol | 1.50 g | 41.73% | 44.88% | 40.16% |
| Phenol | 3.00 g | 48.03% | 65.35% | 47.24% |
The abstract summarizes adsorption efficiency ranges as 99.23-99.72% for Cr, 98.72-99.55% for Ni, and 23.62-48.03% for phenol. The text also describes removal efficiency greater than 99% for Cr and greater than 98% for Ni.
Langmuir parameters at 30 C in Table 2 include Cr Qmax 71.94, 71.43, and 71.43 mg/g at 15, 30, and 45 minutes, each with R2 1.0000. Ni Qmax values at 30 C were 22.03, 21.93, and 21.83 mg/g, each with R2 1.0000. The paper reports several negative Langmuir Qmax or KL values at 35 C, including Cr Qmax -24.39 mg/g at 15 minutes and Ni Qmax -7.79 mg/g at 15 minutes; these are retained as paper-side model-fit outputs, not corrected.
Pseudo-first-order and pseudo-second-order kinetic parameters in Table 3 include PFO K1 values for Cr and Ni ranging from 0.00001 to 0.0405 min-1, and phenol ranging from 0.0021 to 0.0055 min-1 at 30 C and 35 C. The paper reports PSO K2 values for Cr and Ni ranging from -25.66 to 485.75 g/mg-1 min-1, and phenol ranging from -3.64 to 32.41 g/mg-1 min-1. The conclusion states that pseudo-second-order kinetics had the best fit, with most R2 values greater than 0.90.
Methods (brief)
Pineapple-residue biochar was characterized by FTIR and XRD before adsorption. Batch adsorption used 0.50 g, 1.50 g, and 3.00 g biochar dosages in 250 mL conical flasks containing 100 mL landfill leachate. Flasks were agitated at 90 rpm for 15, 30, or 45 minutes at 30 C or 35 C, then filtered and analyzed. Cr and Ni were measured using a Perkin Elmer Pinnacle 900T graphite atomic absorption spectrophotometer. The paper reports total Cr and Ni, not Cr(VI) or nickel species.
Implications
Certification: Do not use these leachate concentrations or removal percentages as pineapple or food occurrence values. They are remediation performance values for a pineapple-residue adsorbent treating landfill leachate.
Courses: Useful example of agricultural-waste biochar as a low-cost heavy-metal remediation material, with high Cr/Ni removal but model-fit outputs that require careful reading.
App: Context only. The source supports remediation and supplier-control narrative for landfill leachate treatment; it does not estimate consumer-product contamination.
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Verification notes
Recovered from skip:not-food-occurrence under the 2026-06-10 inclusion-by-default rule. The old skip treated the paper as out of scope because it was not pineapple food occurrence. On reading, it is in-scope a2 mitigation/remediation evidence because it measures Cr and Ni removal from landfill leachate.
Numbers were checked against the extracted PDF text, especially the abstract, Materials and Methods, Table 1, Table 2, Table 3, and the conclusion. The adsorption-model outputs include negative constants and inconsistent statements about best fit; those values are reported as printed and not normalized. Chromium is total Cr, not Cr(VI). Products and ingredients are intentionally empty.
Page history
The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.
| Commit | Date | Description |
|---|---|---|
| 3110e5f | 2026-06-10 | recover-ingest 2026-06-10: duwiejuah2026-pineapple-biochar-leachate-metals (lane a2, was skip:not-food-occurrence) |