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Unsaturated Soil Water Retention Characteristics, Electrical Conductivity and Compressibility of a Poorly Graded Fujian Soil Amended with Biochar
(2026-07-01)
Liu, Allen
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Garg, Ankit
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Yanning, Wang
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Kamchoom, Viroon
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Zhussupbekov, Askar
This study investigates the effect of peach shell biochar on the unsaturated soil water retention characteristics, electrical conductivity (EC), and its correlation with the compressibility of poorly graded Fujian soil, thereby addressing a critical gap in biochar research for geotechnical applications. The study aims to explore an economical approach to accessing geotechnical properties using EC. Biochar (produced at 600 °C) was mixed with sand at 0%, 5%, and 10% ratios and tested using a modified oedometer for simultaneous EC and compressibility measurements. Results reveal that 10% biochar increased EC by 354 mS/m under 200 kPa stress, a fourfold enhancement over 5% biochar (88 mS/m), attributed to conductive pathways formed by biochar particles under compression. Soil settlement decreased by 17% (0.282ΔH) and 21% (0.268ΔH) at 5% and 10% biochar, respectively, compared to bare sand (0.340ΔH). The air-entry value surged from 0.40 kPa (bare sand) to 0.71 kPa (5% biochar) and 1.41 kPa (10% biochar), enhancing moisture retention by 78% and 253%. The EC-void ratio relationship diverged markedly: bare sand showed a declining EC with reduced void ratio (0.112 Δe), while biochar-amended soils exhibited a rising EC (Δe = 0.056 for 5% and 0.036 for 10%) due to particle conduction dominating over pore-water losses. These findings offer feasible geotechnical applications: the stress-responsive EC enables real-time stability monitoring in embankments or landfill covers via non-invasive resistivity tomography, while reduced compressibility positions biochar-amended sand as a sustainable alternative for foundations in flood-prone or arid regions. Enhanced air-entry values further mitigate drought-induced cracking and erosion. The dual role of biochar, improving conductivity and mechanical stability, supports its integration into green infrastructure strategies.
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Increased erosion in biochar-amended soil: importance of integrating erosion control blankets and vegetation
(2026-03-01)
Hossain, Monir
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Jotisankasa, Apiniti
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Aramrak, Surachet
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Kamchoom, Viroon
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Nishimura, Satoshi
Although biochar is widely recognized for enhancing various soil properties, its impact on soil erosion resistance remains unclear and sometimes shows contradictory results. The main objective of this study is to quantify the effects of corn-cob biochar amendment, both with and without erosion control blankets (ECB), as well as the influence of biochar/compost incubation time on erosion resistance of a silty sand. The study also investigates the effects of biochar on Atterberg limits, shear strength, and thermal conductivity. As biochar content increases from 0 % to 20 %, the liquid limit (LL), plastic limit (PL), and shrinkage limit (SL) rise by 8 %–10 %, suggesting that biochar-amended soil (BAS) retains more water without losing strength. The addition of biochar has minimal impact on the shear strength of BAS at lower normal stresses (<45 kPa) but reduces its thermal conductivity by about 70 %. Submerged jet erosion tests show that biochar alone increases soil erosion in BAS. However, when combined with ECB and vegetation, erosion is significantly reduced (up to 39 %). Overall, this study underscores the importance of utilizing biochar in combination with ECB and such vegetation as ruzi grass to mitigate soil erosion in the silty sand.
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Modeling suction of unsaturated granular soil treated with biochar in plant microbial fuel cell bioelectricity system
(2025-12-01)
Onyelowe, K. C.
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Ebid, Ahmed M.
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Ramos Jiménez, Rosa Belén
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Kamchoom, Viroon
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Vishnupriyan, M.
There is an initiative driven by the carbon-neutrality nature of biochar in recent times, where various countries across Europe and North America have introduced perks to encourage the production of biochar for construction purposes. This objective aligns with the zero greenhouse emission targets set by COP27 for 2050. This research work seeks to assess the effectiveness of biochar in soils with varying grain size distributions in enhancing the soil–water characteristic curve (SWCC). This work further explores the effect of different combinations of biochar content (0 to 15 mass %) on the bioelectricity generation from biochar-improved plant microbial fuel cells (BPMFC). Additionally, different machine learning models such as the “Gradient Boosting (GB)”, “CN2 Rule Induction (CN2)”, “Naive Bayes (NB)”, “Support vector machine (SVM), “Stochastic Gradient Descent (SGD)”, “K-Nearest Neighbors (KNN)”, “Tree Decision (Tree)”, “Random Forest (RF)”, and “Response Surface Methodology” (RSM), have been developed to predict SWCC based on soil suction, electric current, electrical potential, volumetric water content, temperature, and bulk density. The newly established model demonstrates a reasonable ability to predict SWCC and a cheaper technology in predicting the suction of unsaturated soils in relation to the studied bioelectric factors of the BPMFC. Overall, in this research paper, the GB, SVM and CN2 outclassed the other regression techniques in this order thereby proposing the cheapest technology with the highest performance index to predict the SWCC behavior of unsaturated soils in a BPMFC system.
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Carbon capture through solar-driven CO2 gasification of oil palm empty fruit bunch to produce syngas and biochar
(2025-05-15)
Al-Muraisy, Saqr A.A.
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Chuayboon, Srirat
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Soares, Lais Americo
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Buijnsters, J. G.
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Ismail, Shahrul bin
Oil palm empty fruit bunch (OPEFB) is an abundant organic waste in Malaysia that is often disposed of through field burning. A previous study has shown that solar-driven steam gasification of OPEFB can produce hydrogen-rich syngas with an energy upgrade factor of 1.2 and a carbon conversion efficiency of 95.1 %. Beyond its potential as a biofuel, OPEFB can also act as a carbon sink, capturing photosynthetically stored carbon. This study explores the potential of amplifying OPEFB's negative carbon emissions through solar-driven gasification, using CO<inf>2</inf> as the gasifying agent. In this work, a Central Composite Design (CCD) approach was employed to assess the influence of temperature (1100–1300 °C) and CO<inf>2</inf>/OPEFB molar ratio (1.6–3.0) on H<inf>2</inf>/CO molar ratio and energy upgrade factor, with a constant OPEFB flow rate of 1.8 g/min. The results demonstrated that at an energy upgrade factor of 1.4, 94.9 % of the total carbon was converted into syngas with a H<inf>2</inf>/CO molar ratio of 0.3. The maximum observed net carbon capture yield of 0.4 g C/g OPEFB was achieved at 1300 °C and a CO<inf>2</inf>/OPEFB molar ratio of 3.0. The remaining carbon (94.4–95.7 wt %) was converted into biochar with low heavy metal content, which has potential as a soil enhancer.
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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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Influence of biochar on the water permeability of compacted clay subjected to freezing–thawing cycles
(2024-06-01)
Chen, Zhongkui
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Kamchoom, Viroon
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Leung, Anthony Kwan
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Xue, Jiaxiang
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Chen, Rui
Seasonal variation of soil surface temperature, such as freezing and thawing, can induce increases in the water permeability in clay by mobilizing clay pore structure. This kind of weather-induced change in clay behavior may worsen the water-sealing performance during the construction and after closure operation of engineered structures such as soil barriers for tailings or man-made slopes. There is limited knowledge towards the influence of freezing–thawing cycles on clay microstructure and saturated permeability (K<inf>sat</inf>). This study investigated the saturated permeability of clay under freezing–thawing cycles and explored the uses of biochar as eco-friendly amendment to manipulate the permeability of compacted clay. Clay specimens were compacted with different initial water contents (30%, 34%, and 38%). The biochar application rates of 0%, 2%, 4%, 8% (by dry weight) were applied to measure their effects on the permeability of clay specimens. Saturated permeability was measured by the falling head tests. Any variation of biochar amended clay microstructure after freezing–thawing cycles was captured by the scanning electron microscope. The K<inf>sat</inf> was reduced by about one order of magnitude when the biochar application rate was larger than 4%. This may be attributed to the increase in the filling of the biochar particles in the clay intra-aggregate pores upon the transport of liquid water during the repeated freezing–thawing processes. The biochar may thus be recommended to minimize the K<inf>sat</inf> of geo-environmental structures in cold regions when sufficiently large application rate was used to facilitate the pore-filling process.
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Effect of Chemical Fertilizers on the Efficiency of Biochar in Reducing Lead Mobility in Soil
(2024-04-01)
Chaiyaraksa, Chompoonut
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Chaiyasit, Kanokwan
The objective of this research was to investigate the impact of ten different fertilizers on the mobility of lead in soils that had been treated with biochar. The soil used in this study was collected from Chanthaburi Province. To simulate the experimental conditions, this soil was artificially enriched with 550 mg/kg of lead. The synthetic soil was prepared by mixing it with 10% biochar and 0.04% of various chemical fertilizers. To assess the bioavailability of lead in the soil to plants, an extraction process using diethylenetriamine pentaacetate was performed. This allowed researchers to determine how these fertilizers affected the movement and availability of lead in the soil for plant uptake. In the study, it was observed that among the fertilizers tested, urea was the only one that increased the bioavailability of lead in the soil, making it more accessible to plants. Sequential extraction techniques were employed to analyze six different forms of lead in the soil. Interestingly, all fertilizers, except for urea, caused a transformation of lead from less stable forms to more stable forms in the soil. To further investigate the relationship between fertilizer variables and heavy metal uptake, a stepwise linear regression analysis was applied. The results indicated that the mobility of lead in the soil was primarily influenced by the nitrogen content, potassium levels, and sulfate ion concentration in the fertilizers.
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The Influence of Chemical Fertilizers on the Effectiveness of Biochar in Mitigating Cadmium Mobility in Soil
(2024-01-01)
Chaiyaraksa, Chompoonut
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Sangworn, Navapat
The focus of this study was to explore how various fertilizers influence the movement of cadmium in soil treated with biochar. The research utilized a strong acid sandy loam soil from Chanthaburi Province, naturally rich in organic matter with moderate cation exchange capacity and low nitrogen, potassium, phosphorus, sulfate, salinity and chloride levels. The soil was purposely contaminated with 50 mgkg<sup>-1</sup> of cadmium and treated with biochar derived from water hyacinth through pyrolysis at 450°C for an hour. This biochar displayed moderate alkalinity, high organic matter, phosphorus, potassium, and cation exchange capacity, but low nitrogen content. Analytical techniques like Scanning Electron Microscopy and Fourier-Transform Infrared Spectroscopy were employed to study the surface characteristics of the biochar. The cadmium adding soil was blended with 10% biochar and various chemical fertilizers at a 0.04% ratio. Diethylenetriamine pentaacetate (DTPA) extraction was used to assess the bioavailability of cadmium to plants in the soil, while sequential extraction was conducted to identify the different forms of cadmium present in the soil. The study revealed distinct effects of different fertilizers on cadmium mobility. Fertilizers like 46-0-0 and 0-3-0 caused a transformation of cadmium from stable to less stable forms, increasing the bioavailability of cadmium to plants. Conversely, fertilizers such as 15-15-15, 0-0-50, 0-0-60, and 0-52-34 shifted cadmium from less stable to more stable forms, resulting in decreased cadmium extracted by DTPA. Other fertilizers showed no significant impact on cadmium mobility in the soil. A stepwise linear regression analysis highlighted that nitrogen content, potassium content, and electrical conductivity were influential factors affecting cadmium mobility.
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Characterization and Application of Biochar Derived from Snake Fruit Peel for Lead Adsorption
(2024-01-01)
Maneesri, Wisit
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Choolaaied, Orasa
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Phanchindawan, Naree
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Ketpimol, Nopadol
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Limmun, Warunee
Lead (Pb(II)) is a prominent contaminant in industrial wastewater, causing environmental and health risks. Traditional treatment methods often encounter limitations, including high operational costs and low efficiency in dilute solutions. This study presents an innovative, cost-effective solution utilizing biochar derived from snake fruit peels. Two biochar materials, SB500 and SB700, were produced via pyrolysis at 500 °C and 700 °C, respectively. The results indicate that the physicochemical properties of biochar change with increasing pyrolysis temperature. In addition, adsorption kinetics experiments showed that the two biochars displayed rapid adsorption within the first 60 min, with adsorption capacities of 28.08 mg/g for SB500 and 26.68 mg/g for SB700. This behavior can be attributed to a combination of physisorption and chemisorption mechanisms. These findings highlight the significance of the surface properties of biochar, especially its mesoporous structures and functional groups. Furthermore, this study suggested developing an efficient approach to mitigating the environmental and health impacts of Pb(II) contamination while addressing the issue of agricultural waste management.
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Polycyclic Aromatic Hydrocarbons Occurrences in Biomass Char and Its Mitigation Approaches: A Mini Review
(2023-08-01)
Mohd Nor Azman, Nur Aina Najwa
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Asmadi, Mohd
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Amin, Nor Aishah Saidina
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Shamjuddin, Amnani
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Mohammad Zainol, Muzakkir
Biochar is a porous fine-grained substance produced from the pyrolysis technology of biomass that can be commercially used as a soil conditioner to promote soil fertility. Biochar is characterized by high carbon content, stability, and porosity. However, organic pollutants residue of polycyclic aromatic hydrocarbons (PAHs) is also formed during the pyrolysis of biochar. The high concentration of PAHs adversely degrades the quality of biochar for soil amendment application. Meanwhile, highly toxic-PAHs concentration may pose a potential threat to both human health and the environment. The total PAHs yield is mainly influenced by the pyrolysis condition and feedstock resource. This review aims to discuss the conversion pyrolysis technology of biochar and factors that may influence the PAHs formation. The key research findings from this literature will lead to some strategies to minimize the PAHs compound in biochar by controlling the pyrolysis conditions through higher pyrolysis temperature, carrier gas flow, and prolonged pyrolysis time or by selecting suitable feedstock with lower lignin content.

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