Ash Composition Research Articles

Synthesization and characterizations of coal fly ash-coffee grounds-based composite as super-absorbent for application in soil

To recycle and utilize two types of harmful solid waste, coffee grounds (CG) and coal fly ash (CFA), a novel and low-cost superabsorbent composite (MCG-PAA/CFA) was synthesized by aqueous solution polymerization with modified coffee grounds (MCG), acrylic acid (AA) and CFA as raw materials, and it was applied to soil to improve its drought resistance. Various reaction conditions were comprehensively investigated and analyzed to assess their influence on the water absorbency of the superabsorbent composite (SAC). After optimization, the MCG-PAA/CFA exhibited water absorbency capacities of 1260(±10.6) g/g and 82(±1.4) g/g in deionized water and physiological saline, respectively. After adding 3 wt% MCG, the water absorption of SAC was improved from 415 to 746 g/g. After further introduction of 2 wt% CFA, the water absorption of SAC increased from 746 to 1260 g/g. Fourier Transform Infrared (FTIR) analysis confirmed that the grafting reaction was successful and that CFA participated in the reaction, while scanning electron microscope (SEM) and thermogravimetric analysis (TGA) results revealed that the grafting reaction and the introduction of CFA improved the surface morphology and thermal stability of the SAC. Kinetic analysis was conducted to investigate how the grafting reaction and the introduction of CFA affected the swelling and water retention kinetics of the superabsorbent composite. In the soil experiment, adding only 0.1 wt% MCG-PAA/CFA can improve the water holding capacity of sandy soil, loam soil and clay soil by 6.65%, 4.42%, and 3.76% respectively This SAC composite has great potential in soil drought resistance.

Effect of fly ash on mechanical properties and microstructural behaviour of injected moulded recycled polypropylene composites

The global challenges of plastic waste and fly ash accumulation demand innovative recycling solutions. In Malaysia, the consumption of 11.2 million tonnes of coal annually generates approximately 2 million tonnes of fly ash, while the recycling of Polypropylene (PP) is hindered by thermo-oxidative and shear-induced degradation during mechanical recycling, resulting in reduced mechanical properties. This study addresses these issues by fabricating recycled PP composites incorporating varying fly ash contents, using a single cycle of mechanical recycling with extrusion and injection moulding methods. The composites were comprehensively tested for tensile, flexural, and compressive strengths, as well as microstructural behaviour. The results reveal a complex relationship between fly ash content and mechanical performance: while tensile strength decreases with increasing fly ash, flexural strength and strain peak at 5 % and 9 % fly ash, respectively. Compressive strength also shows a slight increase up to 7 % fly ash, indicating an optimal range for enhancing mechanical performance. Furthermore, mathematical models were proposed to predict the mechanical properties of rPP – fly ash composites, providing a valuable tool for future material design. These findings demonstrate that optimization of fly ash content can mitigate the effects of polymer degradation, offering a sustainable solution to improving the mechanical performance of this composite.

Immobilization of heavy metals with chlorine and liquid phase formation during thermal treatment of MSWI fly ash

Due to effective detoxification, thermal treatment is a preferred treatment technology of municipal solid waste incineration (MSWI) fly ash. However, immobilization behavior of heavy metals during thermal treatment is unclear. In this work, a circulated fluidized bed fly ash with SiO2 addition and a grate furnace fly ash with high silica-aluminum coal ash addition were used to investigate combined effect of active chlorine content, liquid polymerization degree, temperature of initial liquid phase formation and liquid phase formation rate on the immobilization ratios of Zn, Pb and Cd by principle component analysis (PCA). The results show that the decrease in active chlorine content favors the immobilization of Zn, Pb and Cd because chlorination volatilization is reduced. Both the increase in liquid polymerization degree and the formation of initial liquid phase at low temperature promote the immobilization of Zn, Pb and Cd for physical encapsulation. However, a rapid formation of liquid phase is not favorable for the immobilization of Zn, Pb and Cd, because transfer of heavy metals between crystals and liquid phase is impeded by high viscosity of liquid phase during fusion. The results can provide a reference for how to achieve the immobilization of heavy metals by adjusting the chemical composition of MSWI fly ash during thermal treatment.

Impact of Spent Mushroom Substrate Combined with Hydroponic Leafy Vegetable Roots on Pleurotus citrinopileatus Productivity and Fruit Bodies Biological Properties.

Agricultural activities produce large quantities of organic byproducts and waste rich in lignocellulosic materials, which are not sufficiently utilized. In this study, alternative agricultural waste products, namely, spent mushroom substrate (SMS) from the cultivation of edible Pleurotus ostreatus mushrooms and the roots of leafy vegetables from hydroponic cultivation (HRL), were evaluated for their potential to be used as substrates for the cultivation of Pleurotus citrinopileatus and their effects on the quality, the nutritional value, the chemical properties (lipid, protein, carbohydrate, ash, fatty acid and carbohydrate composition) and the bioactive content (total phenolic compounds and antioxidant activity) of produced mushrooms. SMS and HRL (in different ratios with and without additives) and wheat straw with additives (WS-control) were used. During incubation, the linear growth rate of the mycelium (Kr, mm/day) was measured and used for screening. Mushroom cultivation took place in bags, where several characteristics were examined: earliness (duration between the day of substrate inoculation and the day of first harvest) and biological efficiency (B.E. %, the ratio of the weight of fresh mushrooms produced per dry weight of the substrate × 100). Furthermore, this study aimed to investigate the effect of the protein extract (PE) and carbohydrate extract (CE) of P. citrinopileatus after in vitro digestion (fraction less than 3kDa: PE-DP-3; digestate fraction: CE-D, respectively) on the expression of antioxidant-related genes in the THP-1 cell line. The results showed that mushrooms grown on SMS 50%-HRL 40% had the fastest growth (6.1 mm/d) and the highest protein and lipid contents (34.7% d.w.; 5.1% d.w.). The highest B.E. (73.5%), total carbohydrate (65.7%) and total phenolic compound (60.2 mg GAE/g d.w.) values were recorded on the control substrate. Antioxidant activity was observed in all extracts; the total flavonoid content was low in the samples, and the maximum total triterpene value was detected in SMS 80%-HRL 20% (9.8 mg UA/g d.w.). In all mushrooms, linoleic acid (C18:2) was the main fatty acid (above 60%), and fructose was the dominant individual saccharide. In the investigation of the regulation pathway, NFE2L2 gene expression was upregulated only in the SMS 60%-HRL 40% intervention during incubation with CE-D samples. Additionally, the transcription levels of antioxidant-related genes, SOD1, CAT, HMOX1 and GSR, were increased in the SMS 60-30% intervention. Compared to WS, the alternative substrates are observed to trigger a pathway concerning CE that may resist oxidative stress. This study supports the utilization of agricultural byproducts through sustainable and environmentally friendly practices while simultaneously producing high-value-added products such as mushrooms. Therefore, alternative substrates, particularly those containing HRL, could serve as natural sources of antioxidant potential.

Role of coal ash morphology and composition in delivery and transport of trace metals in the aquatic environment

Fly ash is predominately the inorganic byproduct of coal combustion for electrical power generation. It is composed of aluminosilicates with Fe, Mg, K, and Ca forming submicron to 100 μm spheres and amorphous particles. During combustion trace elements are incorporated into the heterogenous fine particles that can pose risks to the environment and human health. This study combines optical, rock magnetic, and geochemical analyses of fly ash originating from Appalachian coal to develop an integrated suite of environmental coal ash tracers. The non-magnetic portion of power plant fly ash has higher abundance of clear spheres and clear amorphous particles, combined with enrichment of As, B, Th, Ba, Li, Se, Cd, Pb, and Tl. The magnetic fraction is enriched in opaque and orange spheres and Cu, U, V, Mo, Cr, Ni, and Co. Plerospheres occur in either fraction. We investigated ash-bearing fluvial sediment from Emory-Clinch River system that was impacted by the instantaneous TVA spill in 2008 and Hyco Lake in North Carolina that was contaminated by chronic releases of fly ash since 1964. Five years after the TVA spill, most ash in the riverbed reflects one population with trace element concentrations proportional to percent total ash. This relationship does not hold for As and Se, volatile elements associated with the outer surface of clear spheres, which are affected by river transport. At Hyco Lake, small clear and opaque spheres correlate with trace elements released from storage ponds. The combination of trace elements, fly ash morphology and rock magnetism provides a powerful set of tools to assess the distribution of ash and potential impact on the environment. We conclude that dispersal of fly ash to the aquatic environment, especially small clear and opaque spheres, should be avoided in favor of dry landfills.

Impact on Incorporation of Purple Yam Flour (Dioscorea alata var. Purpurea) in Development of Multigrain Nutri-Bar

Consumption of wholesome and healthy diet is the most effective way to combat protein-energy malnutrition and micro-nutrient deficiencies. Present study was carried out to develop a nourishing and cost effective nutri-bar from selected locally available yams, cereals, legumes and oil seeds. Incorporation of purple yam flour at 20% (F1), 15% (F2) and 10% (F3) was performed with changing only the ratio of processed rice flour.The highest mean rank scores for all tested sensory properties of appearance, taste, texture, aroma and overall acceptability were observed in F1. Proximate composition of ash, protein, fat, crude fiber, carbohydrate and calorie contents of products ranged 1.26-1.37%, 11.20-12.02%, 6.57-7.29%, 2.69-3.58%, 73.28-73.41% and 397.57 - 406.81 kcal/100g respectively. The highest values for total sugar, crude-fibre, potassium, sodium, calcium were recorded in F1 with 20.06±0.12%, 3.55±0.08%, 3903±2.8mg/kg, 396.50±10.60mg/kg, 305.00±29.70mg/kg respectively. F1 had the highest TPC- 4.120 mg GAE/g, TFC- 0.179 mg QE/g, anthocyanin content- 0.225 mg/g and antioxidant potential through DPPH assay- 3.142 mg TE/g followed by F2 and F3. The anthocyanin content of three formulas showed significantly positive correlation with antioxidant capacity (r =1.00, p<0.05). In conclusion, nutri-bars are the excellent source of nutrients supplements especially for undernourished population.

Elemental composition of post-wildfire biomass ashes and partly burned woody species in Bohemian Switzerland National Park, Czech Republic.

The study explored the post-wildfire elemental composition of parts (wood, bark, branch, cone, trunk, litter, twig, needle, sward, fallow, sapling, etc.) and by-products (biomass ashes, partly burnt parts, and char) of different woody species in the Bohemian Switzerland National Park, Czech Republic, and considered their effects on soils. Multi-elemental analysis of the fire by-products of the woody species was determined with inductively coupled plasma-optical emission spectrometry and mass spectrometry and compared with control biomass samples unaffected by wildfire. Most fire by-products were slightly alkaline, with acidic ashes obtained from blueberry wood. The by-products of the wildfire were characterized by varied total contents of macro (P, Ca, K, Mg, and S), micro (Na, Mn, Fe, Cu, and Zn), and other elements (B, Co, Mo, and V) vital to soil fertility and plant growth. The mean content of macro elements in the biomass ashes was up to 4.16 P, 23.5 Ca, 2.48Mg, 63K, and 5.57 S g kg-1. These values were comparatively lower than published data for ashes obtained under optimized conditions, e.g., those combusted in power generation facilities. Conversely, partly burnt parts-an indication of incomplete combustion-had higher 9.22 P, 79 Ca, and 5.99Mggkg-1 contents in spruce needles than in biomass ashes and the control. Variations in woody species and anthropogenic activities in areas of wildfires produced varied As, Cd, Cr, Ni, and Pb contents above EU fertilizer regulation. Caution in applying biomass ashes from wildfires on fields is required due to risk/toxic elements input from anthropogenic activities. Wildfire effects on the elemental composition of woody species can provide information on plant parts most suitable for biomass ashes for soil and ecosystem safety.

Assessing the Potential of Rare Earth Elements in Bottom Ash from Coal Combustion in Poland.

The aim of the research was to assess the potential of bottom ash from Polish coal-fired power plants as an alternative source of rare earth elements (REY). The potential of these ashes was compared with fly ash from the same coal combustion cycle. The phase and chemical composition, as well as REY, were determined using: X-ray diffraction and inductively coupled plasma mass spectrometry. The tested ashes were classified as inert-low pozzolanic and inert-medium pozzolanic, as well as sialic and ferrosialic, with enrichment in detrital material. The phase and chemical composition of bottom ash was similar to fly ash from the same fuel combustion cycle. The REY content in the ash was 199-286 ppm and was lower than the average for global deposits, and the threshold value was considered profitable for recovery from coal. Bottom ash's importance as a potential source of REY will increase by recovering these metals from separated amorphous glass and mullite and grains rich in Al, Mg, K, and P. The industrial value of bottom ash as an alternative source of REY was similar to fly ash from the same fuel combustion cycle.

The influence of the composition and origin of ash and slag waste from coal generation on the response of organisms used in biotesting

Introduction. Different conditions of origin of ash and slag wastes has a significant impact on their final properties. Material and methods. The work is devoted to the search and establishment of dependencies of the influence of the origin of ash and slag waste on their chemical and biological parameters by a comprehensive assessment of the results of the impact of ash and slag waste on the vital signs of hydrobionts. Results. The values of the responses of hydrobionts for ash and slag wastes formed from coals of various origins were investigated. The component composition of aqueous extracts from the studied ash slag samples was evaluated. The dependences of the influence of the conditions of origin of ash and slag wastes on their final chemical and biological properties were established. Limitations. An assessment of the biological and chemical properties of ash and slag waste generated during the combustion of coal from six different deposits was carried out. The total volume was 95 samples. Conclusion. Ash and slag wastes formed from the burning of brown coals have the most pronounced toxic effect on hydrobionts, unlike ash and slag from coal.

Studies of the phase composition and ultrafine structure of the initial domestic raw materials of proppants

The results of the study of intracrystalline electric and magnetic fields in samples on 57Fe nuclei by the ultrafine method of the Mossbauer effect are considered. The source of gamma radiation was 57Co in the chromium matrix. The spectra of the samples were measured on 57Fe nuclei using the MS1104Em spectrometer in the mode of constant accelerations at room temperature for absorption. The crystal structure, phase composition, and electronic states of individual components of the proppants are given. The measurements were carried out on the d8 Advance universal complex (Bruker, Germany). The data of parameters recorded on detectors of secondary energy characteristics of X-rays corresponding to K, L, M, N and O levels of electronic transitions using computer processing of elemental compositions and their ratios in samples are analyzed. The data of X-ray studies of the composition of fly ash are presented, determining its potential application in various industries, including the production of proppants. The results of the analysis of the chemical composition of bauxite samples obtained by X-ray diffraction analysis are presented. The silicon modulus (µSi) has been determined, which is the ratio of Al2O3 to SiO2 to characterize the quality of bauxite. The main components of bauxite were Al2O3 (aluminum oxide) and SiO2 (silicon dioxide). A significant content of Fe2O3 (iron oxide) was also noted, which is 24-33 wt. % for bauxite.

Proximate composition and colour profile of honey from Northern and Southern Guinea Savannah Zones of Niger State, Nigeria

This study evaluates the proximate composition and colour profile of honey harvested from the Northern and Southern Guinea Savannah zones of Niger State, Nigeria. The samples were gathered from nine Local Government Areas: four from the Northern Guinea Savannah Zone and five from the Southern Guinea Savannah Zone. The analysis included moisture, ash, protein, lipid, fibre, carbohydrate content, and colour composition of the honey samples. The samples showed that there were significant differences (p>0.05) in moisture content, crude protein and carbohydrate content between samples from the Northern and Southern Guinea Savannah zones of Niger State. However, there were no significant differences in the ash and fat content in the honey samples from both Northern and Southern Guinea savannah zones of Niger State. The honey had an amber colour value of 12 - 36.11%, carbohydrate content of 78.32-84.16%, crude protein of 0.16-0.20%, an ash content of 0.56-0.63% and fat content of 0.20-0.21%. The results of the proximate analysis indicated that all examined parameters fell within the codex standard, with the exception of the retailed samples, which had slightly lower carbohydrate contents in both zones. These findings suggested that geographical location within Niger State significantly influences the physicochemical properties of honey, which could impact its quality, marketability, and potential health benefits. Further research is recommended to explore the factors driving these regional differences and their implications for honey production and consumption.

Analyzing empirically and optimizing surface roughness and tool wear during turning aluminum matrix/rice husk ash (RHA) composite

Analyzing empirically and optimizing surface roughness and tool wear during turning aluminum matrix/rice husk ash (RHA) composite

Deadman Behavior and Slag–Iron–Coke Interaction of Low Carbon and Safety Blast Furnace: A Review

The elucidation of the deadman's behavior and the interaction between slag–iron–coke within the blast furnace hearth are essential for the realization of low‐carbon and safe production. In this review, the macrostate of the deadman, the interactions between slag–iron–coke, carburizing behaviors, and renewal mechanisms are comprehensively examined. First, the formation and state of the deadman, voidage, and the distribution of coke sizes within the blast furnace hearth are characterized. The average coke particle size ranges from 20 to 30 mm, and the deadman void fraction of 30–50%. Second, the interaction between slag–iron–coke as well as the occurrence state of the mineral layer at the interface within the deadman is elucidated. The ash composition and content of coke are the key factors affecting the slag–iron–coke interaction and interface phase composition. Third, the influence exerted by critical factors such as the physical properties of the carbon source, molten iron, and temperature on the carburizing behavior are analyzed, with the renewal mechanisms of the deadman also being disclosed. Finally, three future focal areas are proposed: characterization and intelligent monitoring of deadman permeability, analysis of slag–iron–coke properties and interface mineral layers control, and in‐depth analysis of deadman renewal and carbon carburization in molten iron. It is anticipated that the studies will enhance the comprehension of deadman behavior and the interactions between slag–iron–coke, thereby fostering the blast furnace's sustainable development.

Study of the chemical composition of coal and coal ash by X‐ray fluorescence method: A review

Study of the chemical composition of coal and coal ash by <scp>X‐ray</scp> fluorescence method: A review

Development, modelling and optimization of process parameters on the tensile strength of aluminum, reinforced with pumice and carbonated coal hybrid composites for brake disc application

This study focuses on optimizing double stir casting process parameters to enhance the tensile strength of hybrid composites comprising aluminum alloy, brown pumice, and coal ash, intended for brake disc applications. Analytical techniques including X-ray fluorescence, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy were employed to characterize the composite constituents. The Taguchi method was utilized for experimental design and optimization to determine the optimal weight compositions of brown pumice and coal ash, as well as stir casting parameters (stirrer speed, pouring temperature, and stirring duration). Regression analysis was employed to develop a predictive mathematical model for the tensile strength of the hybrid composites and to assess the significance of process parameters. The optimized composite achieved a predicted tensile strength of 186.81 MPa and an experimental strength of 190.67 MPa using 7.5 vol% brown pumice, 2.5 vol% coal ash, a pouring temperature of 700 °C, stirrer speed of 500 rpm, and stirring duration of 10 min. This represents a 52.23% improvement over the as-cast aluminum alloy’s tensile strength. Characterization results revealed that brown pumice and coal ash contain robust minerals (SiO2, Fe2O3, Al2O3) suitable for reinforcing metal matrices like aluminum, titanium, and magnesium. Thermogravimetric and differential thermal analyses demonstrated thermal stability up to 614.01 °C for the optimized composite, making it suitable for brake disc applications.

Erratum to: Optimizing Shear Strength Performance of Incinerator Bottom Ash Composites Using Neural Networks

Erratum to: Optimizing Shear Strength Performance of Incinerator Bottom Ash Composites Using Neural Networks

Compressive Strength Study on Reactive Powder Concrete with 30% Quartz Sand and Variations in Fly Ash Composition as Partial Substitution of Cement

The concrete industry is considered environmentally unfriendly and unsustainable due to the significant consumption of natural materials. Currently, the industry predominantly uses Portland cement as its main ingredient, leading to an increase in Portland cement production. However, the use of fly ash can help make the concrete industry more sustainable in the future. Fly ash can be used as a partial replacement for Portland cement in concrete production. This study aims to determine the effect of fly ash variations on the compressive strength of reactive powder concrete. The research method used is experimental. The concrete mix design includes 30% quartz sand and fly ash variations of 0%, 5%, 10%, 15%, 20%, and 25%. The compressive strength test specimens are cylindrical with a diameter of 7.5 cm and a height of 15 cm. The resulting test specimens have a compressive strength of more than 41.4 MPa, thus qualifying as high-strength concrete. The compressive strength test results for fly ash variations of 0%, 5%, 10%, 15%, 20%, and 25% are 62.62 MPa, 66.27 MPa, 75.59 MPa, 68.78 MPa, 66.21 MPa, and 63.70 MPa, respectively.

Nutritional composition, fatty acids, bioactive compounds, and antioxidant activity of Nigella sativa seed grown in Bangladesh

Black cumin seeds are extensively utilized for foods, cosmetics, and medicinal purposes. The current investigation was undertaken to analyzse the nutritional values, fatty acid compositions, bioactive compounds, and antioxidant roles of different black cumin genotypes available in Bangladesh. The genotype BSK-2074 had a higher content of proximate composition of crude oil (35.17%), crude protein (23.51%), total carbohydrate (35.23%), moisture (6.54%), ash (3.74%), crude fiber (8.12%), and gross energy value (644.88 kcal/100 g) than the released varieties and cultivars of black cumin available in Bangladesh. The major fatty acid profile of the seed-oil of the BSK-2074 genotype revealed that the oil contained a high amount of linoleic (59.39%), oleic (25.72%), palmitic (13.11%), and stearic (2.25%) acids, as well as a low amount of arachidic, linolenic, myristic, behenic, palmitoleic, lignoceric, and eicosadienoic acids. Moreover, the genotype BSK-2074 contained a high amount of unsaturated (UFAs, 85%), and low content of saturated (SFAs, 18%) fatty acids, and the ratio of UFAs to SFAs was higher (4.39–5.37). Again, the seeds of the genotype BSK-2074 were also enriched in different minerals, viz., calcium, magnesium, potassium, phosphorus, iron, and zinc. Moreover, total phenolic contents (TPC) and flavonoid contents (TFC) were found significantly higher in the genotype BSK-2074 (478.47 ± 7.33 mg GAE/100 g and 284.07 ± 2.08 mg QE/100 g, respectively) than the local Kalozira variety (316.48 ± 2.33 mg GAE/100 g and 120.53 ± 3.57 mg QE/100 g) found in Bangladesh. The activities of antioxidants 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radicals and ferric reducing antioxidant power (FRAP) were found significantly higher in BSK-2074 (37.93% and 129.65 ± 0.19 mg GAE/100 g), than the local Kalozira variety (98.09% and 193.75 ± 0.19 mg GAE/100 g). Thus, the new genotype, BSK-2074, was identified and suggested as the most promising and nutritionally enriched genotype of black cumin.

Mix design determination procedure for geopolymer concrete based on target strength method

This study presents the development and validation of a mix design determination procedure for geopolymer concrete to achieve the desired compressive strength. The procedure integrates artificial neural network (ANN) model developed based on a comprehensive data base from literature, data clustering, and parameter optimization techniques to enhance accuracy and reliability. Experimental validation is undertaken to demonstrate the mix design determination procedure’s capability to accurately predict mix designs for geopolymer concrete based on the target compressive strength, validating its efficacy for mix proportion determination. The integration of chemical oxide content in fly ash, curing time, curing temperature, and activator properties results in a 15.9% improvement in prediction accuracy for the training dataset and a 68.3% enhancement for the testing dataset, compared to the base ANN model that includes only the weight of fly ash and activator properties. Employing data clustering techniques enables the identification of prior estimates for the mix design parameters related to specific fly ash types and target compressive strength, streamlining the mix design process by analyzing pertinent data subsets. Parameter optimization ensures refined mix proportions, achieving the desired target strength economically while minimizing material waste and cost. The development of a user interface facilitates easy manipulation of mix designs, catering to users of varying expertise levels. Additional options for deeper insights into geopolymer concrete characteristics can be integrated into the mix design determination procedure. To assess the mix design determination procedure's ability to generalize effectively, a variety of fly ash samples with distinct chemical compositions were utilized, differing from those already present in the database. This approach allows for a thorough evaluation of the mix design determination procedure's performance when presented with fly ash compositions it has not encountered before. By doing so, this provides insights into the adaptability of the mix design determination procedure beyond the limitations of the training and testing datasets.

SURFACE MODIFICATION OF FLY ASH FROM ASAM-ASAM COAL POWER PLANT USING STEARIC ACID AS HYDROPHOBIC INORGANIC MATERIAL

Abundant coal reserves make this material a substitute fuel choice, especially for industry. The use of coal carries a high risk due to incomplete combustion and produces fly ash products. Fly ash cause pollution and health risks as well as environmental contamination when they are released, deposited, or leached into the ecosystem over short or long periods of time. The high content of silica and alumina in fly ash can be utilized and modified into new materials with added value. This research aims to modify the surface of fly ash using stearic acid as a hydrophobic inorganic material. Fly ash from Asam-asam Coal Power Plant was characterized by using XRD and modified by immersing in stearic acid (2,4,6, and 8%) and 98% ethanol. The result showed that the contact angle increases when fly ash is modified on the surface using stearic acid. The contact angle increases with increasing stearic acid concentration. The highest contact angle was obtained at a stearic acid concentration of 8%, and the lowest at 2% was about 112.9 and 102.2, respectively. The fly ash composition was primarily silica and alumina, which were crystalline, as confirmed by XRD. These findings provide several aspects of fly ash and its potential as a candidate material for environmental remediation and waste management.