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Bombax ceiba-based carbons for dye removal

The intensity ratio of the D to G bands (ID/IG) Bc-H displayed a fragmented and highly porous
serves as a semi-quantitative indicator of disorder. The morphology, with interconnected mesopores clearly
calculated ID/IG values were 1.0, 1.2, and 1.3 for Bc-H, visible. This structure reflects the dual role of H PO
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Bc-K, and Bc-Na, respectively. These results indicate as both a dehydrating and crosslinking agent. During
that Bc-H possessed the lowest degree of structural carbonization, H PO stabilizes the carbon framework
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disorder, suggesting a relatively more ordered sp and inhibits tar formation, resulting in uniform pore
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carbon network compared to Bc-K and Bc-Na. This development and enhanced structural integrity. The
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observation correlates well with the XRD results, which well-formed mesoporous network observed in Bc-H
also revealed a somewhat better-defined (002) peak corresponds closely with its high BET surface area and
for Bc-H, although the structure still remains largely amorphous characteristics, as supported by XRD and
disordered and turbostratic (amorphous). Raman data. Notably, prior studies have shown that
When interpreting the structure of the ACs, Bc-H H PO activation is effective at moderate temperatures
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exhibited moderate graphitization and fewer defects, (400 – 500°C), consistent with the pore development
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which may enhance uniformity in surface chemistry and observed in this study.
facilitate better adsorption. Bc-K and Bc-Na had higher The Bc-K sample exhibited a more compact and
ID/IG ratios, reflecting more disordered structures and layered surface with fewer discernible pores. While
greater defect densities, which are consistent with the KOH is a well-established activating agent, it generally
broader Raman and XRD features. requires higher temperatures (700 – 800°C) to promote
All samples are predominantly amorphous, as effective microporosity through redox interactions with
confirmed by XRD and Raman analyses. However, carbon. At 400°C, these reactions are limited, leading to
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Bc-H displayed comparatively lower disorder and a underdeveloped pore structures and low mesoporosity.
more organized carbon matrix. This improved structural The SEM findings align with Bc-K’s relatively low
integrity may support more efficient dye adsorption and surface area and higher disorder, as revealed by BET
contribute to enhanced performance in environmental and Raman analyses, indicating incomplete activation
or electrochemical applications. 18 at the applied temperature.
The Bc-Na sample revealed a porous yet irregular
3.2.3. SEM analysis morphology, featuring macro pore-like voids and signs
The surface morphologies of the AC samples – Bc-H, of localized expansion macro pore-like voids and
Bc-K, and Bc-Na – were examined through SEM, signs of localized expansion. These features are likely
as presented in Figure 4. The results illustrate how caused by internal gas release and thermal stress during
chemical activation and thermal treatment influence Na CO decomposition. However, similar to KOH,
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pore formation and surface texture in the B. ceiba- effective activation with Na CO typically requires
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derived carbons. higher temperatures (~700°C or above) for sufficient
All samples exhibited porous features formed through pore development. 13,21 The 400°C treatment used here
activating agent-driven etching of the biomass during likely limited its activating effect, resulting in uneven
carbonization. These chemical activators promote porosity and reduced mesopore content.
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porosity by reacting with the carbon matrix, causing SEM analysis revealed clear differences in pore
dehydration, expansion, and localized leaching. 19 morphology among the AC samples. Bc-H showed the

Figure 4. Scanning electron microscopic images of Bc-H, Bc-K, and Bc-Na samples. Bc-H, Bc-K, and
Bc-Na refer to acid-activated, base-activated, and salt-activated carbons, respectively. Scale bar: 20 µm,
magnification: 20,000×.

Volume 22 Issue 4 (2025) 193 doi: 10.36922/AJWEP025240191