Overview
Stevens and Batlokwa tested pulverized, vinegar-treated fish-scale waste as a biosorbent for Pb(II) and Zn(II) removal from wastewater. This is in-scope mitigation evidence for heavy-metal removal and fishery-waste valorization, not vinegar occurrence or fish-product occurrence.
Key numbers
The abstract reports that the pulverized fish-scale waste had particle size 60 um and that FTIR identified amines, carboxylic, hydroxyl, and carbonyl functional groups. The XRD analysis showed hydroxyapatite, which the authors link to ion-exchange behavior with metal ions.
For untreated and vinegar-treated fish scales, the results state that Pb2+ was not detected in untreated fish scale, while Zn2+ was detected at 0.013 mg/g. After vinegar treatment, the Zn2+ initially present in untreated fish scales was no longer detectable.
The optimized adsorption parameters printed in Table 3 are:
| Parameter | Optimized value |
|---|---|
| pH | 7.52 |
| Sorbent dosage | 76.99 mg |
| Contact time | 62.37 min |
| Initial concentration | 24.45 mg/L |
Before applying the method to real wastewater, the wastewater sample was spiked with 2 mg/L of each selected ion. Recoveries were 102 +/- 2.03% for lead (II) and 107 +/- 1.44% for zinc (II).
The results paragraph reports triplicate real-wastewater removal values as “Zn2+ and Pb2+ were 81.97 +/- 1.023 and 80.37 +/- 1.45 at n = 3 respectively.” The abstract describes “Lead (II) and Zinc (II)” removal as 81.97% and 80.37%, so the paper is internally ambiguous about which metal receives which percentage. This page preserves the result-paragraph ordering rather than assigning the abstract values to a metal silently.
Methods (brief)
Fish scales were collected from fish from Lake Ngami in Sehitwa near Maun, washed, sun dried for 48 hours, pulverized at 400 rpm for 90 minutes, sieved to 63-200 microns, washed again, treated with white spirit vinegar containing 12.67% acetic acid, and dried at 65 +/- 5 degrees C for 6 hours. Functional groups were characterized by FTIR; crystallinity by XRD; morphology and elemental composition by SEM-EDX; and metals by ICP-OES. Adsorption optimization used two-level fractional factorial design and central composite design in Minitab.
Related evidence
Update history
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