Page 210 - AJWEP-22-4

Shrestha

These results confirm that Bc-H not only meets but Freundlich), kinetic modeling (pseudo-first and second-
also exceeds the performance of many reported biomass- order), and thermodynamic studies were not performed
based adsorbents, especially in terms of removal speed, due to the extremely rapid equilibrium behavior
dosage efficiency, and practical applicability. observed with Bc-H. In addition, post-adsorption
While this study employed FTIR and SEM for surface characterization (e.g., FTIR or X-ray photoelectron
and morphological analysis, more advanced techniques – spectroscopy) and point of zero charge measurements
such as carbon, hydrogen, nitrogen, and sulfur elemental were not included, which limits mechanistic
analysis and transmission electron microscopy – were interpretation. Moreover, all adsorption experiments
not included. These will be incorporated in future were carried out at room temperature, which restricts
work to provide a deeper understanding of elemental understanding of temperature-dependent adsorption
composition and nanostructure, further enriching the behavior and thermodynamic parameters.
characterization of Bc-H. To address these gaps, future work will focus on:
(i) performing equilibrium isotherm, kinetic, and
4. Conclusion thermodynamic modeling under broader time and
concentration ranges, (ii) investigating the adsorption
This study presents a systematic and comparative mechanism in more detail using post-adsorption surface
evaluation of ACs synthesized from B. ceiba wood analyses (FTIR, X-ray photoelectron spectroscopy),
dust using three different chemical activating agents – (iii) exploring variable activation temperatures and
H PO , KOH, and Na CO – for the adsorption of RhB impregnation ratios, especially for KOH and Na CO
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from aqueous solutions. activation routes, (iv) evaluating the effect of temperature
Among these, Bc-H consistently exhibited the on adsorption capacity and deriving key thermodynamic
highest adsorption efficiency, fastest kinetics, and most parameters (ΔG°, ΔH°, ΔS°), (v) expanding applicability
favorable physicochemical properties. Its superior to other classes of pollutants, including heavy metals
performance is attributed to its high BET surface area and emerging contaminants.
(1,451.2 m /g), well-developed mesoporosity, and The B. ceiba-derived AC, particularly Bc-H, offers
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abundance of surface oxygenated functional groups several notable advantages, such as low-cost synthesis
introduced during H PO activation. These features from abundant local biomass, high BET surface area, well-
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collectively promoted rapid dye diffusion and strong developed mesoporosity, and outstanding RhB removal
electrostatic, hydrogen bonding, and π–π interactions efficiency. However, certain disadvantages remain. The
with RhB molecules. Compared to Bc-K, Bc-Na, and study was conducted under controlled batch conditions
even commercial AC, Bc-H achieved nearly complete using synthetic dye solutions; thus, its performance under
RhB removal (>99%) within just 2 – 4 min, highlighting complex real wastewater conditions requires further
its strong potential for real-time water purification. validation. In addition, the regeneration and reuse of
Key operational parameters were also optimized. the adsorbent were not evaluated, which is critical for
The best performance was observed at pH = 8.5 and practical field applications. Addressing these aspects will
an adsorbent dose of 0.03 g/100 mL. In contrast, Bc-K be essential for future scaling and deployment.
and Bc-Na performed less effectively due to lower In summary, Bc-H emerges as a low-cost,
surface areas and limited mesoporosity, with Na CO sustainable, and highly effective adsorbent for organic
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showing negligible activation efficiency at the applied dye removal. Its excellent adsorption capacity, ultrafast
temperature. kinetics, and eco-friendly synthesis method make it a
This work underscores the critical importance of promising candidate for scalable wastewater treatment,
activation strategy in tailoring surface area, porosity, particularly in decentralized or resource-limited settings
and functional group chemistry for optimal adsorption such as rural areas in Nepal and beyond.
performance. The one-step H PO activation at a
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moderate temperature (400°C) represents a cost- Acknowledgments
effective and scalable route for converting B. ceiba
sawdust – a widely available waste biomass in Nepal The author expresses sincere gratitude to the Institute of
– into high-performance AC. Science and Technology (IOST), Central Department of
While the current study provides compelling results Chemistry, Tribhuvan University, Kirtipur, Nepal; Patan
under batch conditions, it also has a few limitations. Multiple Campus, Tribhuvan University, Patan Dhoka,
Detailed adsorption isotherms (e.g., Langmuir and Lalitpur; the Global Research Laboratory, Sun Moon

Volume 22 Issue 4 (2025) 202 doi: 10.36922/AJWEP025240191