Journal of Applied Materials and Technology

Graphene Oxide–TiO2 composite materials for photocatalytic degradation of organic pollutants in water treatment

2026-02-23T08:40:34+07:00

The increasing presence of recalcitrant organic pollutants in water bodies has driven the development of advanced treatment technologies capable of promoting effective degradation beyond conventional processes. In this study, a graphene oxide (GO)–titanium dioxide (TiO2) composite was synthesized via a chemical route and evaluated for photocatalytic degradation of methylene blue under UVC irradiation. Graphene oxide was produced by electrochemical exfoliation of graphite, followed by incorporation into TiO2 at 5 wt.% to form the TiO2:GO5 composite. Structural and morphological characterizations by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and FTIR confirmed the formation of anatase-phase TiO2 and successful integration of GO without secondary phase formation. Photocatalytic performance was assessed by monitoring dye concentration decay over 5 h of irradiation. The TiO2:GO5 composite achieved more than 70% methylene blue removal, reaching a final C/C0 value of 0.28, compared to 0.29 for pure TiO? under identical conditions. The degradation followed pseudo-first-order kinetics, with apparent rate constants of 2.302 × 10-¹ h-¹ for the composite and 2.241 × 10-¹ h-¹ for pure TiO2, corresponding to a 2.7% increase in reaction rate. Enhanced initial adsorption and slightly faster absorbance decay were observed for the composite throughout the irradiation period. Although the performance enhancement is moderate, the incorporation of graphene oxide improved charge separation and adsorption behavior without requiring high-temperature calcination. These findings demonstrate that GO modification represents a viable strategy to enhance TiO2 photocatalytic activity under energy-efficient synthesis conditions, highlighting its potential application in advanced water and wastewater treatment systems.

Quantum accessory for solar panels: a sustainable solution to improve energy efficiency based on the circular economy

2026-02-06T19:47:17+07:00

Carbon quantum dots (CQDs) have emerged as promising spectral modifiers for photovoltaic devices due to their photoluminescent down-conversion properties. In parallel, silica-rich industrial residues represent an environmental liability but also a potential source of functional materials. This study investigated the valorization of SiO2-rich mining residue for the production of a sodium silicate matrix incorporating CQDs as a spectral conversion overlayer for solar panels. The treated residue successfully yielded sodium silicate, and CQDs were synthesized and integrated into the matrix. Photovoltaic testing demonstrated that panels coated with industrial-derived sodium silicate exhibited an initial efficiency increase of 8.91% compared to standard panels. However, coatings containing CQDs with the residue-derived sodium silicate showed reduced performance in early-stage testing, and all samples exhibited progressive opacity after six months, indicating limited long-term stability. These findings highlight both the potential and the challenges of integrating CQD-based spectral management with mining residue valorization. While the approach demonstrates feasibility in short-term performance enhancement, material stability remains a critical barrier for practical implementation.

Influence of borax addition on setting behavior and mechanical properties of Class F fly ash geopolymer concrete

2025-12-27T06:49:18+07:00

The role of borax as a setting-time modifier in Class F fly ash-based geopolymer concrete is not yet well understood. Particularly with respect to its effects on mechanical and fresh properties. This research investigates the influence of borax incorporation on the properties of geopolymer concrete. Class F fly ash from the Tanjung Jati B power plant was used. Borax was added at fly ash weights of about 0%, 5%, 10%, and 15%. Tests were arranged to observe setting time, compressive strength, elastic modulus, and slump value to assess mechanical performance and workability. The results represent, borax effectively prolongs the initial and final setting times, with greater effectiveness in Class F fly ash (low CaO) than in Class C fly ash (high CaO). The addition of 5% borax resulted in a higher compressive strength and modulus of elasticity. However, higher borax dosages reduced mechanical properties by inhibiting geopolymerization. An increase in borax content reduced slump values, reflecting lower workability due to higher mixture viscosity. While borax can effectively regulate setting time in Class F fly ash–based geopolymer concrete, its dosage must be carefully optimized to prevent negative effects on strength and fresh concrete performance.

Finite Element-Based Validation of Infill Wall Material Model for Seismic Response Analysis of Reinforced Concrete Frames

2025-11-28T21:02:25+07:00

Masonry infill walls are commonly used in reinforced concrete (RC) frame buildings for both architectural and environmental reasons. Although many consider RC systems to be non-structural, their interaction with surrounding frames can have a significant impact on their lateral stiffness, strength, and seismic performance. This can lead to stiffness issues and soft-story failures during earthquakes. This study looks at the structural function of masonry infills. It compares the experimental load-displacement backbone curve of an infilled RC frame with numerical predictions from four well-known Equivalent Diagonal Strut (EDS) models: Holmes, Mainstone, Liau and Kwan, and Paulay and Priestley. We looked at how well the models performed for both serviceability (initial stiffness) and ultimate limit states (peak lateral strength). The findings demonstrate a definite trade-off in predictive accuracy. With a mean stiffness ratio of 1.38, the Mainstone model yielded the most accurate estimate of elastic stiffness. The Holmes and Liau and Kwan models, on the other hand, significantly overestimated stiffness (ratio = 1.92). All models were conservative (ratios < 1.0) for peak strength. Holmes and Liau and Kwan produced the closest predictions (ratio = 0.84), while Mainstone was the most conservative (ratio = 0.80). These results indicate that the best choice of EDS model depends on the design goal: Mainstone is better for serviceability assessments, while Holmes and Liau and Kwan provide more realistic predictions for ultimate lateral capacity.

Preparation and characterization of MoS2 thin films for thermoelectric applications using the PVD technique

2025-11-15T20:41:12+07:00

Molybdenum disulfide (MoS₂) is a two-dimensional material with electronic and thermal properties that make it promising for thermoelectric applications. This research presents the results of synthesizing and characterizing MoS₂ thin films obtained by Physical Vapor Deposition (PVD) on silicon dioxide (SiO₂) substrates. Three experimental approaches were explored to assess how changes in deposition conditions affect the material quality. In the first trial, films were formed from commercial MoS? powder in a sulfur-rich (S₂) atmosphere using a PVD tubular furnace. Next, water vapor (H₂O) was added to the process to observe possible improvements in material formation. Finally, silver doping was investigated, introduced during deposition to examine structural and vibrational changes in the MoS₂. The samples were characterized by Optical Microscopy (OM) and Scanning Electron Microscopy (SEM), as well as Energy Dispersive Spectroscopy (EDS), used to evaluate surface morphology and composition. X-ray Diffraction (XRD) was employed to identify the crystalline structure, while Raman Spectroscopy revealed the E₂g¹ and A₁g vibrational modes, associated with the crystallinity of the material. The results indicated that the presence of H2O during deposition favored the growth of more ordered films, with more intense peaks in XRD and Raman spectra. On the other hand, silver doping caused vibrational changes that suggest modifications in the electronic structure of MoS₂. These findings reinforce the material’s potential for use in thermoelectric devices and demonstrate that variations in synthesis conditions can significantly enhance its structural and functional properties.

Powder metallurgy synthesis of Pd-doped MoS2: A structural and morphological study

2025-10-14T07:16:29+07:00

This study reports the synthesis and structural characterization of palladium (Pd)-doped molybdenum disulfide (MoS?) produced via the powder metallurgy route. The primary objective was to investigate how Pd incorporation influences the structural, morphological, and electrical properties of MoS?, thereby demonstrating the advantages of powder metallurgy compared to conventional synthesis techniques. The materials were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy. XRD confirmed the retention of the hexagonal MoS? phase without the formation of secondary Pd-related phases, indicating successful substitutional doping. SEM–EDS analyses revealed a uniform Pd distribution and progressive morphological evolution with increasing Pd content, characterized by enhanced surface roughness and improved particle dispersion. FTIR and Raman spectra showed modifications in bonding environments and vibrational modes, evidencing the structural influence of Pd atoms on the MoS? lattice. Electrical measurements, performed using both I–V and four-point probe methods, demonstrated a conductivity increase from 9.6 × 10?? S·m?¹ for pure MoS? to 1.6 × 10?? S·m?¹ and 1.9 × 10?? S·m?¹ for the 1% and 2% Pd-doped samples, respectively. This enhancement is attributed to the higher charge carrier density and improved interlayer charge transport induced by Pd doping. These findings confirm that powder metallurgy provides an effective and scalable synthesis pathway for achieving homogeneous Pd incorporation in MoS?. The resulting materials exhibit excellent structural integrity and enhanced electrical performance, making them promising candidates for catalytic, sensing, and energy storage applications.

Fly ash adsorbent for ph improvement and manganese reduction in acid mine drainage

2025-10-05T11:30:59+07:00

Metal solid waste from coal combustion (fly ash) is abundant in Indonesia, as an effective and economical adsorbent in neutralizing acid mine drainage (AMD). Given that the continuous utilization of coal produces environmental challenges in the form of AMD containing acid residues and heavy metals such as manganese (Mn), an appropriate treatment solution is required. The adsorption method was chosen due to its simplicity, cost effectiveness, and ability to remove heavy metal pollutants. The purpose of this research is to characterize fly ash before and after heating by SEM and XRD analysis, and evaluate the effect of fly ash physical activation temperature by heating at 100^oC and 200^oC for an interval of 60 minutes on the characteristics and adsorption ability of fly ash. In addition, this study also evaluated the effectiveness of the adsorbent mass (fly ash before heating and after heating) in increasing pH and reducing Mn concentration in AMD so that it meets the quality standards of Class 1 river water. The results obtained from this study show a fundamental difference in the properties of fly ash before and after heating. Based on BET analysis, the physical activation process resulted in pore enlargement (0.196 nm) and increased surface area of the adsorbent (0.847 m²/g), which significantly affected its binding capacity to solutes (adsorption capacity). The application of fly ash as an adsorbent showed the ability to increase the pH value of acid mine drainage towards neutral conditions. The process of reducing heavy metal ions Mn by using 50 g of fly ash heating at 100^oC and 200^oC, resulted in a removal percentage of 94.74% and 98.44%. It is hoped that this research can provide innovative and sustainable AMD treatment and increase the use value of fly ash waste.

From waste to value: Lapachol from teak wood waste as a green catalyst for sustainable soda cooking of Acacia and Eucalyptus

2025-09-24T20:38:01+07:00

The development of a sustainable catalyst as an alternative to synthetic anthraquinone (AQ) is urgently needed for a more efficient pulping process. This study investigates the potency of lapachol, a natural naphthoquinone isolated from teak (Tectona grandis) wood waste, as a catalyst in soda cooking of three industrially important hardwoods: Acacia crassicarpa, Eucalyptus pellita, and Eucalyptus globulus. Approximately 97.7% purity of lapachol was isolated and applied at 0.09% (on oven-dry wood). For comparison, the commercial synthetic additive, 2-Methylanthraquinone (2-MAQ) was also used at the same dosage. Cooking experiments were conducted at 160°C under varying alkali dosages (23, 27, 31%) and times (4, 5, 6 h). The result revealed that the delignification performance was species-dependent: A. crassicarpa (S/V=0.74) was the hardest, while E. globulus (S/V=3.04) was the easiest to delignify. Notably, E. pellita (S/V=2.04) shows the greatest selectivity index. Lapachol shows the capability of enhancing delignification across the three wood species by decreasing the residual lignin by up to 5% in A. crassicarpa, 5% in E. Pellita, and 2% in E. globulus compared with soda cooking (control). Although the delignification is slightly lower than 2-MAQ, lapachol maintains pulp yields comparable to or higher than 2-MAQ. The selectivity index analysis confirmed that lapachol improved the balance between lignin removal and carbohydrate preservation, with the benefits most pronounced in E. globulus. These findings underscore lapachol as a promising sustainable pulping catalyst, offering the potential for impactful industry transformation through sustainable innovation.

Photo-Fenton of Dyes Degradation Using Covalent Triazine Frameworks: Toward Industrial Wastewater Treatment Applications

2025-08-03T19:42:05+07:00

A Covalent Triazine Framework (CTF-1) and carbon nanospheres (CS) were synthesized to develop a porous, thermally stable, and efficient photocatalyst for dye degradation in wastewater treatment applications. The synthesized composite material exhibited a high surface area exceeding 400 m²/g, a well-defined mesoporous structure, and excellent optical properties, including strong light absorption extending up to 550 nm and a moderate band gap of approximately 2.8 eV. These characteristics promote effective visible light-driven photocatalysis. The photocatalytic performance was assessed by degrading methylene blue (MB) as a model organic dye pollutant under photo-Fenton conditions. The system demonstrated high efficiency, with over 90% of the dye removed within 120 minutes of irradiation. The degradation followed pseudo-first-order kinetics, confirming the photocatalytic nature of the reaction. Parameter studies indicated that hydroxyl radicals (•OH) were the dominant reactive species responsible for dye degradation. Moreover, CTF-1 retained its photocatalytic activity and structural integrity over multiple reuse cycles, showcasing excellent reusability and stability. The integration of high surface area for dye adsorption, efficient photoactivation under visible light, and robust radical generation synergistically contributed to the enhanced degradation performance. The study highlights the promising role of CTF-1 and its composites as multifunctional materials for advanced oxidation processes. Given its effectiveness, durability, and environmental compatibility, CTF-1 presents a sustainable and scalable solution for the treatment of dye-laden industrial wastewater. This work contributes to the development of next-generation photocatalysts aimed at addressing global challenges in water pollution and environmental remediation.

Web-Based System for Statistical Analysis and Thesis Progress Monitoring

2025-06-21T09:10:53+07:00

Web-based monitoring systems serve as valuable tools in enhancing learning activities, particularly in the context of thesis supervision. Program heads and academic supervisors require timely, accurate information regarding students’ progress to guide academic outcomes effectively. This paper presents the development and implementation of an integrated web-based statistical and monitoring application tailored for thesis progress reporting. Built using the Laravel framework, the system incorporates statistical data visualization to enable students, supervisors, and administrators to interpret progress and communicate insights effectively. The system was developed using the prototype method, allowing iterative improvements based on user feedback. To ensure quality and functionality, the system was evaluated using the ISO/IEC 25010 quality model. A case study conducted in an electrical engineering department at a public university in Indonesia, involving students, academic supervisors, and administrative staff. The results demonstrate that the system not only improves oversight and coordination but also supports data-driven decision-making. By offering a clear, accessible overview of thesis progress, the application empowers all parties to take timely corrective actions, ultimately enhancing the overall educational experience.