ABSTRACT Coal combustion has recently faced immense negative publicity because of its potential impact on climate change. This negativity has obscured the fact that coal combustion remains a significant contributor to global energy utilization and is likely to remain so for some time. It is prudent, therefore, to continue finding the most environmentally sensible implementations for the burning of coal. This includes both efficient combustion and the effective reuse of coal fly ash. Modifications of coal boilers for NOx control made maintaining low residual carbon in boiler fly ash more difficult, and determining the appropriate char reactivity to use in simulating coal-fired combustors is a critical characteristic for optimal design. This paper describes a residual carbon-in-ash study. Experiments are conducted in a tubular, downward-fired, refractory-lined, laminar entrained flow reactor (EFR) that provides the coal with up to a 2 s residence time under conditions of pilot-scale boilers. Two types of coals are used in order to affirm the predictions of a simple kinetics-diffusion (KD) model from FLUENT® and a detailed oxidation char burnout kinetics (CBK) model. A thermo-gravimetric analyzer (TGA) provides comparative oxidation understanding. The three-dimensional KD model included convective and radiative heat transfer at the boundaries, along with heterogeneous and homogeneous combustion chemistry, to evaluate char burnout kinetics validated with the experiments. The results show that the KD model can successfully achieve essentially equivalent carbon in ash predictions, based on loss on ignition (LOI), at the late stages of char burnout as does the more sophisticated CBK model.

ABSTRACT Coal-derived char has shown improving the geotechnical performance of cement-stabilized soils. This study aimed to assess the effects of coal char on the hydraulic and durability characteristics of a soil mixture composed of equal sodium bentonite and sand, stabilized with 20% cement. The addition of coal char enhanced both hydraulic and durability properties of the cement-stabilized soil. The inclusion of coal char in cement-stabilized soil further reduced the saturated hydraulic conductivity (Ksat) up to 38%, suggesting decreased water infiltration and greater soil compaction. The soil freezing characteristic curve (SFCC) showed that adding char to cement-stabilized soil samples retained more unfrozen water after 12 freeze-thaw (FT) cycles, which can reduce frost heave for better freeze–thaw resistance. Soil water characteristic curve (SWCC) results demonstrated that char addition improved moisture retention at low suction levels, which could prolong hydration, reduce shrinkage & cracking, and improve drought resilience in arid environments.

Drying completion determinant is critical in coconut charcoal briquette production due to both cost and quality concerns. To address this, research was conducted to determine the drying level of briquettes using resistivity measurements with plate electrodes and electrolytes. The study aimed at finding the possibility of applying combination of plate electrodes and electrolytes for rapid determination of stopping the drying process in coconut shell charcoal briquette production. In this study, two distinct methods were performed: the direct approach and the indirect approach. On one hand, the direct method applied Ohm’s Law to current and voltage data. On the other hand, the indirect method utilized a voltage divider approach to calculate resistivity. Both methods were conducted to test the cube-shaped briquettes (2.5 cm per side) with moisture content (MC) levels ranging from 4% to 16%. The direct method provided results close to rod electrodes. Meanwhile, the indirect approach provided very precise results with deviation standard less than 1.5%. The resistivity of the threshold of market acceptable briquette was above 10 kohm.m for moisture content less than 5%. These findings indicate a clear distinction between wet and dry briquettes, demonstrating the possibility of applying the instrumentation of a fast stop drying determinant. The indirect method can reduce decision time and fuel cost by 5%.

Indoor Air Quality (IAQ) is a pressing issue in densely populated and poorly ventilated spaces, where pollutants such as PM2.5, PM10, and excessive humidity contribute to health risks including Sick Building Syndrome (SBS). This study proposes a passive and sustainable solution through Coconut Waste Interior Panels (CWIP), made from a 50:50 mixture of activated coconut charcoal (CCAC) and coconut fiber, packaged in perforated wooden boxes. Experiments were conducted in a 27 m³ enclosed room with four scenarios: with/without CWIP and with/without fan circulation, using mosquito coil smoke as the pollutant source. The results showed a significant improvement in indoor air quality (IAQ), with CWIP reducing PM2.5 from 65.67 µg/m³ to 40.27 µg/m³ and PM10 from 82.73 µg/m³ to 49.93 µg/m³ (p < 0.001) without fan circulation. A moderate decrease was also observed with fan assistance. Humidity decreased significantly under static conditions. These findings highlight CWIP as an effective, electricity-free, and environmentally friendly alternative, supporting waste utilization and sustainable indoor air quality improvement in resource-limited and environmentally conscious settings.

The impact of media coverage of a celebrity suicide on suicide and attempted suicide rates in Taiwan.

In-situ investigation of coal particle fragmentation and char evolution during gasification

Carbon monoxide (CO) intoxication can lead to various brain lesions, with the globus pallidus being the most common site of injury. Herein, we report a rare case of CO poisoning with acute bilateral hippocampal lesions and delayed midbrain involvement of the substantia nigra. A woman in her twenties who attempted suicide by burning charcoal briquettes presented with a Glasgow Coma Scale score of 3/15. Initial head computed tomography revealed low-density areas in the bilateral globus pallidus and hippocampi. Magnetic resonance imaging (MRI) on day 3 showed high signal intensity in the same regions on diffusion-weighted imaging (DWI), with a corresponding low signal on the apparent diffusion coefficient map and high signal intensity on fluid-attenuated inversion recovery imaging. The patient underwent hyperbaric oxygen therapy (HBOT) and gradually regained consciousness. However, the patient experienced persistent short-term memory loss. Follow-up MRI on day 23 showed improvement in the hippocampal and globus pallidus lesions but revealed new bilateral high-signal lesions in the substantia nigra on DWI. Despite these findings, the patient did not exhibit any extrapyramidal signs. Subsequent HBOT sessions led to further improvements in her cognitive function, as evidenced by an increase in her Mini-Mental State Examination score from 13/30 to 27/30. This case highlights the importance of serial neuroimaging in CO poisoning, as delayed midbrain lesions may occur more frequently than previously thought, even in the absence of overt neurological symptoms. The patient's cognitive recovery and lack of parkinsonism suggests that early intervention with HBOT may help mitigate the long-term consequences of CO-induced brain injury.

CFD simulation on a particle cluster consists of coal char and Fe-based oxygen carriers: Pressurized heat-mass transfer

Thermal deactivation mechanism of coal char during underground coal gasification

The Zhundong coalfield in Xinjiang contains vast reserves and is a crucial source of thermal coal. However, the Zhundong coal has a high content of alkali and alkaline earth metals, which makes it prone to ash deposition and slagging in boilers, thereby limiting its large-scale utilization. Fluidized-bed preheating is an emerging clean combustion technology that can reduce the slagging and fouling risks associated with high-alkali coal by modifying its fuel properties. This study employs circulating fluidized-bed preheating technology to treat high-alkali coal, with a focus on investigating the effect of the preheated air equivalence ratio on fuel preheating modification. Through microscopic characterization of both the raw coal and preheated char, the release and transformation behaviors of elements and substances during the preheating process are revealed. The results demonstrate that fluidized preheating promotes alkali metal precipitation, and increasing the preheated air equivalence ratio (λPr) enhances gas production and elemental release, with a volatile fraction mass conversion of up to 84.57%. As the λPr value increased from 0.28 to 0.40, the average temperature in the preheater riser increased from 904 °C to 968 °C. Compared to the raw coal, the specific surface area of the preheated char was enhanced by a factor of 3.6 to 9.1 times, with a more developed pore structure and less graphitization, thus enhancing the surface reactivity of the preheated char. The increase in λPr also facilitated the conversion from pyrrolic nitrogen to pyridinic nitrogen, thus improving combustion performance and facilitating subsequent nitrogen removal. These findings provide essential data support for advancing the understanding of preheating characteristics in high-alkali coal and for promoting the development of efficient and clean combustion technologies tailored for high-alkali coal.

The physicochemical properties, thermal conversion performance, and kinetic characteristics of pressurized pulverized coal gasification slag.

Enzyme-Induced Carbonate Precipitation (EICP) has emerged as a sustainable and efficient bio-cementation technique to improve the mechanical properties of sandy soils by promoting the formation of calcium carbonate. However, the effectiveness of EICP is often constrained by environmental factors affecting urease activity and the limited availability of nucleation sites. This study investigates the incorporation of coal char as an additive to EICP-treated sandy soil to enhance its mechanical strength. Soybean-derived urease was used to catalyze the EICP process, with coal char added at varying concentrations (0%, 5%, 10%, and 20% by weight of soil). The treated samples were evaluated through unconfined compressive strength (UCS), triaxial compression tests, calcium carbonate content analysis, thermal conductivity measurements, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results indicate that highest compressive strength and calcite precipitation were observed at the soil with 10% coal char content. The inclusion of 10% coal char significantly improved the compressive strength of EICP-treated soil by 35.65%, 33.58%, 22.5%, and 16.50% at 3, 7, 14, and 28 days, respectively. Similarly, their calcium carbonate precipitations increased by 8.33%, 21.87%, 21.70%, and 31.81% over the same time intervals compared to the EICP-treated samples without coal char. This increase in calcium carbonate also led to a corresponding rise in the density of the coal char-treated mixtures. These enhancements are attributed to the porous structure of coal char, which provides additional nucleation sites for mineralization. These findings demonstrate that EICP-coal char mixture forms a novel, low-carbon bio-cementation system that can be deployed in situ as a sustainable alternative to conventional cementitious stabilizers. This technique not only strengthens weak sandy soils but also offers broader engineering value by providing an environmentally friendly ground-improvement strategy and future sustainable soil-stabilization practices.

Coal Char as an Additive: Effects on Cement-Stabilized Soils with High Bentonite Content

This test aimed to determine the effect of loaded and unloaded coconut shell charcoal briquettes with tapioca and starch adhesives on the AC electric motor RPM during the briquette-making process, and to obtain optimal hardness values for both coconut shell charcoal briquettes with tapioca and starch adhesives. The hardness testing method for coconut shell charcoal briquettes used the Brinell hardness test, using samples of coconut shell charcoal briquettes with tapioca and starch adhesives. The measurement used was an optical one, measuring the size of the indentation left by the indenter. Standard optical hardness testing methods include the Brinell hardness test (ISO 6506, ASTM E10). Based on the results of the briquette machine test for 7 minutes with a load of 15 kg, the coconut shell charcoal with starch adhesive produced an AC electric motor RPM of 702.9, while the coconut shell charcoal with tapioca adhesive produced an AC electric motor RPM of 884.7. The average hardness test results of coconut shell charcoal briquettes with tapioca adhesive have a value of 17.33 HRB, while coconut charcoal briquettes with starch adhesive have a value of 21.36 HRB. The hardness value of coconut shell charcoal briquettes with starch adhesive is harder or more optimal than coconut shell charcoal briquettes with tapioca adhesive.

Chlorine-resistant Ca–Cu and Ba–Cu oxygen carriers in chemical looping combustion of coal and biomass

Tar formation remains a major bottleneck for the sustainable utilization of biomass gasification, and catalytic reforming is an effective route for tar conversion. Among various catalyst systems, carbon-based catalysts exhibit unique advantages due to their tunable pore structures, adjustable surface chemistry, and intrinsic electrical conductivity. Unlike non-carbon supports, conductive carbon matrices actively regulate coke evolution by facilitating electron transfer at metal-carbon interfaces, thereby promoting carbon dissolution-precipitation pathways and the transformation of amorphous coke into ordered graphitic structures. This distinctive 'coke management' behavior mitigates active-site encapsulation and directly links electrical conductivity to catalyst stability and long-term reforming performance. Based on structural controllability and functional mechanisms, carbon-based catalysts can be classified into two categories: conventional carbon catalysts (e.g., biochar and coal char), which are low-cost and readily available but exhibit structural heterogeneity, and advanced carbon catalysts (e.g., MOFs-derived carbons, carbon nanotubes, and graphene-based materials), which possess ordered pore networks, well-defined metal-support interactions, and highly graphitized conductive frameworks. While conventional carbons are attractive for large-scale application, their disordered microstructures limit precise control over mass transfer, metal dispersion, and coke evolution. In contrast, advanced carbon materials provide model platforms to elucidate structure-activity-stability relationships and to establish transferable design principles. This review integrates recent progress in both catalyst classes, emphasizing how insights from advanced carbon systems can guide the targeted modification of conventional carbons, and proposes a unified framework linking conductivity, coke behavior, and durability for the rational design of efficient and stable carbon-based catalysts for biomass tar reforming.

This study aimed to evaluate the bleaching efficacy and effects of dentifrices containing tricalcium phosphate (TCP) with activated charcoal (COAL) or hydrogen peroxide (HP) on dental enamel, compared with monofluorophosphate (MFP). Bovine enamel-dentin discs (n=10/groups) were stained and divided into TCP/HP, TCP/COAL, MFP/HP, MFP/COAL, and C (control - remineralizing solution) groups. Simulated toothbrushing (5.000 cycles) was performed, representing 6 months of clinical condition. The whiteness index (ΔWID), color changes (ΔE00, ΔL, Δa, and Δb), and surface microhardness and roughness (SMH, Ra) were evaluated after staining and treatments. Morphology and mineral content were analyzed under scanning electron microscopy and energy-dispersive X-ray spectroscopy. Data were analyzed using ANOVA/Tukey or Bonferroni tests (α=5%). MFP/COAL demonstrated significantly higher Δa and Δb than C. A statistically significant difference was observed in the TCP groups only for Δa. MFP-containing groups exhibited significantly higher ΔE00 than C. All groups showed negative ΔWID. MFP/COAL promoted greater darkening than TCP-containing and C groups (p<0.05). No statistical difference was detected among groups for ΔL, SMH, Ra, and %SHL (microhardness loss) (p>0.05). No morphological alterations were observed. TCP/HP showed lower mean Ca/P values. Therefore, dentifrices containing TCP associated with HP or COAL showed no bleaching efficacy and no harmful impact on enamel surface properties.

N2O and NO formation influenced by metal elements during coal pyrolysis and char combustion

NO reduction over biomass char and coal char blends in CO2/H2O atmospheres: Mechanism and potassium effects

Anthropogenic activities have increasingly altered the structure and functioning of tropical forest ecosystems, leading to changes in species composition, diversity, and carbon dynamics. This study assessed the effects of human-induced disturbances on woody species composition, diversity, structure, and carbon storage in Mkuti Forest Reserve, Kasulu District, Tanzania. A sampling intensity of 0.0117% was used, consisting of 71 systematically distributed plots of 0.08 ha each, spaced 2.5 km along plots and transects respectively. The total sampled area covered 5.68 ha out of the 48,638.93 ha of the reserve. Each 20 × 40 m plot was subdivided into two 10 × 10 m subplots to ensure adequate representation of forest conditions and human-induced impacts. Collected data were analysed using Generalised Linear Models (GLMs) to examine the effects of disturbances on species diversity, stem density, basal area, and carbon storage. The Shannon–Wiener index was used to compute diversity, while aboveground biomass (AGB) was estimated using the Mugasha et al. (2013) allometric model for Miombo woodlands developed for the Katavi Region. A total of 88 woody species belonging to 64 genera and 35 families were identified, with Fabaceae being the most dominant. Species diversity was high (H’ = 3.63 for adult trees and H’ = 3.33 for regenerants). Stem density (608 ± 338 stems ha⁻¹) showed a reverse J-shaped curve, signifying active regeneration. The mean basal area was 3.42 ± 1.62 m² ha⁻¹, reflecting the effects of selective logging and recurrent disturbances. Mean aboveground biomass and carbon stocks were 16.96 ± 8.44 t ha⁻¹ and 9.22 ± 4.99 t C ha⁻¹, respectively. Farming significantly reduced diversity, basal area, and carbon storage, while wildfires affected stem density. Other activities, such as grazing, tree cutting, and charcoal burning, had moderate effects. Degradation of the dominant Miombo genera in MFR drives a successional shift toward secondary woodland. As these climax species decline, disturbance-tolerant and fast-growing species increasingly dominate due to coppicing ability, drought tolerance, and rapid germination. Overall, Mkuti Forest Reserve still holds high biodiversity and regeneration potential, but increasing human disturbances threaten its ecological integrity and carbon sequestration capacity. Strengthening community participation, boundary enforcement, and livelihood diversification is crucial to ensure the long-term ecological values of Mkuti Forest Reserve.