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Sustainable magnetic biochar from agro-aquacultural waste for efficient Pb(II) and Cd(II) removal: Machine learning–assisted optimization and techno-economic evaluation
(2026-05-15)
Limmun, Wanida
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Limmun, Warunee
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Prangmoo, Yasumin
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Ishikawa, Nao
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Borkowski, John J.
This study presents the sustainable synthesis and optimization of magnetic biochar derived from agro-aquacultural waste, specifically rubber seed shells and oyster shells (MRO), for the efficient removal of Pb(II) and Cd(II) from aqueous solutions. MRO was synthesized via FeCl<inf>3</inf> activation and co-pyrolysis, enhancing adsorption capacity and magnetic recoverability. Process optimization was performed using Response Surface Methodology (RSM) and a Genetic Algorithm–Backpropagation Neural Network (GA–BPNN), with experimental validation confirming RSM-predicted conditions. The optimized MRO achieved high adsorption capacities of 709.99 mg/g for Pb(II) and 332.98 mg/g for Cd(II), following Langmuir and pseudo-second-order kinetic models. Mechanistic analysis identified surface complexation, ion exchange, electrostatic interaction, and precipitation as key pathways. MRO demonstrated excellent reusability, maintaining over 90% Pb(II) removal efficiency after 11 regeneration cycles. Techno-economic and environmental assessments revealed a low production cost (23 THB/kg), modest energy consumption (2.5 kWh/kg), and a reduced carbon footprint (0.50 kg CO<inf>2</inf>/kg). These results underscore the potential of MRO as a cost-effective and scalable adsorbent for sustainable wastewater treatment applications.
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Sustainable tropical fruit peel waste biochars for enhanced cadmium and lead adsorption: mechanistic insights and optimization using response surface methodology and backpropagation neural networks
(2025-08-01)
Limmun, Wanida
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Limmun, Warunee
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Maneesri, Wisit
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Pewpa, Orrawan
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Chungcharoen, Thatchapol
Heavy metal contamination, particularly from cadmium (Cd(II)) and lead (Pb(II)), presents a severe environmental challenge due to its toxicity and persistence. This study explores an innovative approach by utilizing abundant yet underutilized tropical fruit peel waste to produce biochars that serve as effective, sustainable adsorbents for heavy metal remediation. Biochars derived from banana peels (BP) and Monthong durian shells (DS) were synthesized via pyrolysis at 400–800 °C and evaluated for their physicochemical properties and adsorption efficiency. The DS600 biochar exhibited the highest adsorption capacity, removing Cd(II) (40.37 mg/g) and Pb(II) (51.74 mg/g), surpassing BP600 (40.22 mg/g and 47.23 mg/g, respectively). This study introduces a dual-modeling framework by integrating response surface methodology (RSM) with backpropagation neural network (BPNN) to optimize adsorption conditions and enhance predictive accuracy. The optimized conditions achieved over 99% removal efficiency, with R2 > 0.98 and MSE < 0.05, confirming the robustness of the model-based predictions. The study highlights the superior adsorption performance of DS600 biochar, with adsorption mechanisms influenced by pH, dosage, and biochar properties. In contrast to conventional studies that focus solely on equilibrium adsorption or rely on statistical models, this work pioneers the use of tropical fruit peel biochar in heavy metal remediation, providing quantitative insights into process optimization and practical scalability. The findings demonstrate the potential for valorizing agricultural waste into high-performance adsorbents, advancing cost-effective and sustainable water treatment technologies.
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Comparative Analysis of Biochar Properties from Lemon and Kumquat Peels at Different Pyrolysis Temperatures
(2025-01-01)
Limmun, Wanida
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Limmun, Warunee
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Ito, Ayumi
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Choolaaied, Orasa
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Phanchindawan, Naree
This study examines the effects of pyrolysis temperatures (500 °C and 700 °C) on the properties of biochar derived from lemon peel (LB), kumquat peel (KB), and their combination (LKB). The study analyzed the variations in biochar yield, elemental composition, and specific surface area. The results indicated that higher temperatures led to a reduction in yield but a significant improvement in specific surface area, pore volume, and carbonization, ultimately producing more stable and aromatic biochar. Additionally, LB700 and KB700 exhibited more developed pore structures and higher specific surface areas than those produced at 500 °C. Elemental analysis showed an increase in carbon content and a decrease in hydrogen content at elevated temperatures, suggesting improved biochar stability. These findings demonstrate that higher pyrolysis temperatures enhance the specific surface area and carbon content of biochar, making it more suitable for environmental applications such as soil quality improvement and pollutant adsorption. The study highlights the potential of using commonly discarded agricultural waste, such as lemon and kumquat peels, for biochar production.
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Eco-friendly magnetic biochar from Leb Mu Nang banana peel: Response surface methodology optimization for Cd(II) adsorption from synthetic wastewater
(2024-02-01)
Limmun, Wanida
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Limmun, Warunee
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Borkowski, John J.
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Ishikawa, Nao
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Pairintra, Rattanachai
Magnetic biochar derived from Leb Mu Nang banana peel waste is introduced as a novel precursor for Cd(II) removal from synthetic wastewater. This study comprehensively evaluates and optimizes variable factors, including initial Cd(II) concentration, magnetic biochar (MLP) dosage, adsorption time, and initial pH level, using the Response Surface Methodology (RSM). A Cd(II) removal efficiency of up to 93.4 % is reached under the conditions of a 50 mg/L initial concentration, 5 g/L MLP dosage, 24 h of adsorption time, and a solution pH of 8. The pseudo-second-order and Langmuir models accurately represent the kinetics and isotherm adsorptions, highlighting ion exchange, surface complexation, and precipitation as primary adsorption mechanisms. The magnetic biochar derived from Leb Mu Nang banana peels shows promise for efficient Cd(II) removal with easy post-adsorption separation.
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One-Step Synthesis of Magnetic Biochar from Durian Shell Via K2FeO4 Activation for Lead Removal
(2024-01-01)
Pewpa, Orrawan
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Limmun, Warunee
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Ito, Ayumi
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Chungcharoen, Thatchapol
This study explores the synthesis and application of magnetic biochar derived from durian shell (MDS) for Pb(II) removal. MDS was synthesized through a one-step method using K<inf>2</inf>FeO<inf>4</inf> activation. The synthesized MDS was characterized using various analytical techniques, showing a high specific surface area and oxygen-rich functional groups. These characteristics have made it highly effective at adsorbing Pb(II). The initial pH and MDS dosage effects on Pb(II) adsorption were examined. The highest adsorption capacity of MDS for Pb(II) was found to be 87.43 mg/g, which was observed at pH 7 and MDS dosage of 1 g/L. The pseudo-second-order (PSO) model was found to be the best fit for the kinetics of Pb(II) adsorption, suggesting chemisorption. These results are expected to contribute to the development of effective, economical, and environmentally friendly solutions for wastewater treatment, mainly targeting Pb(II) contamination.
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Exploration of an efficient method for removing antibiotics from water and digested sewage sludge using Fe(VI): Kinetics and P phytoavailability and compostability in treated sludge
(2023-09-01)
Limmun, Warunee
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Ishikawa, Nao
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Maeda, Takeki
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Umeda, Takayuki
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Song, Jie
Potassium ferrate (K<inf>2</inf>FeO<inf>4</inf>) containing hexavalent iron [Fe(VI)] is an environmentally friendly oxidant, which possesses strong oxidizing power to treat wastewater and sludge. Therefore, the present study investigated degradation of selected antibiotics, namely levofloxacin (LEV), ciprofloxacin (CIP), oxytetracycline (OTC), and azithromycin (AZI), in water and anaerobically digested sewage sludge samples using Fe(VI). The effects of different Fe(VI) concentrations and initial pH values on antibiotic removal efficiency were evaluated. Under the studied conditions, LEV and CIP were almost completely removed from water samples, following second-order kinetics. In addition, over 60% of the four selected antibiotics were removed from sludge samples using 1 g L−1 Fe(VI). Furthermore, P phytoavailability and compostability of Fe(VI)-treated sludge were evaluated using different extraction reagents and a small composting unit. The extraction efficiency of phytoavailable P using 2% citric acid and neutral ammonium citrate was approximately 40% and 70%, respectively. The mixture of Fe(VI)-treated sludge and rice husk was self-heated in a closed composting reactor through the biodegradation of organic matter derived from the treated sludge. Therefore, Fe(VI)-treated sludge may be used as an organic material containing phytoavailable P for compost.
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Degradation of the endocrine-disrupting 4-nonylphenol by ferrate(VI): biodegradability and toxicity evaluation
(2022-03-01)
Limmun, Warunee
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Ishikawa, Nao
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Momotori, Jin
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Terasaki, Masanori
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Sato, Takumu
4-Nonylphenol (4-NP) is an endocrine-disrupting and persistent chemical and is partially degraded in conventional wastewater treatment processes. Ferrate(VI) can be used as an environment-friendly oxidizing agent to mediate 4-NP degradation. Thus, this paper evaluates the biodegradability of 4-NP and its degradation products after the addition of ferrate(VI). The biodegradability was examined using NP labeled with 14C as a tracer and activated sludge microorganisms as an inoculum. The addition of ferrate(VI) to the 4-NP solution spiked with the tracer resulted in no remarkable decrease in the concentration of 14C, indicating incomplete mineralization of 4-NP and formation of degradation products. The degradation products from 4-NP with Fe(VI) were estimated based on mass spectra, which detected a unique peak at m/z 223 at low intensity. Four hydrogen atoms might have been added to 4-NP by degradation with Fe(VI). In addition, the effect of ferrate(VI) concentration on the estrogenic activity of 4-NP in an aqueous solution was investigated using a yeast bioassay. The results show that estrogenic activity was significantly decreased at a mass ratio of Fe(VI) to 4-NP greater than or equal to 2.5.

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