Environmental regulations increasingly demand sustainable technologies for treating high-strength agro-industrial wastewater such as palm oil mill effluent (POME), which contains complex organic pollutants and high chemical oxygen demand (COD). In this study, manganese oxide-modified cerium dioxide (MnOx/CeO2) photocatalysts were synthesized via a sol-gel method and evaluated for POME degradation using an immersed photoreactor equipped with a 300 W xenon lamp. The effects of solution pH, Mn loading, and catalyst dosage were systematically investigated. Among the prepared catalysts, 20% MnOx/CeO2 exhibited the highest performance under the optimum conditions of pH 5 and 2 g L-1 catalyst loading, achieving 50.4% photocatalytic COD degradation and 73% total COD removal, including the contribution of dark pre-adsorption. The catalyst also showed a pseudo-first-order rate constant of 0.003 min-1 for COD removal and 0.0032 min-1 for decolorization. Comprehensive characterization using XRD, UV-Vis DRS, BET-BJH, SEM-EDX, HRTEM, XPS, PL, photocurrent response, and EIS revealed that MnOx incorporation narrowed the bandgap, enhanced visible-light absorption, increased surface area, introduced mixed Mn2+/Mn3+/Mn4+ redox states, enriched surface-active oxygen species, and improved charge separation and interfacial charge transfer. Reactive species trapping experiments indicated that superoxide radicals (•O2-) played the dominant role in POME degradation, with photogenerated holes and hydroxyl radicals also contributing. The 20% MnOx/CeO2 photocatalyst maintained appreciable activity over repeated regeneration-assisted cycles, although partial activity loss was observed due to possible catalyst loss, surface fouling, and active-site blockage. This study highlights MnOx/CeO2 as a promising photocatalyst for the sustainable treatment of POME.

ABSTRACT The design of carbon supports critically governs the viability of electrochemical CO2 reduction (ECO2R) in full‐cell configurations. Herein, tin (Sn) catalysts were electrodeposited onto two widely used gas diffusion substrates—Toray Carbon Paper (TCP) and Sigracet Carbon Paper (SCP)—to elucidate the role of substrate architecture in a proton exchange membrane (PEM) CO2 electrolyser. Despite identical catalyst compositions and electrodeposition conditions, Sn/TCP achieves a Faradaic efficiency of 12.82% with only 30% current loss over 180 min, while Sn/SCP collapses by 96% under the same conditions. Detailed structural and electrochemical analyses reveal that TCP's open fibre network and lower resistivity enable uniform Sn nucleation, reduced charge‐transfer resistance and a remarkable 20‐fold increase in surface area during operation. Conversely, the hydrophobic microporous layer in SCP restricts the accessibility of ions and CO2, leading to heterogeneous deposition, accelerated instability and catastrophic catalyst detachment. These results demonstrate that carbon support selection is not a passive engineering decision but directly dictates catalyst utilisation, interfacial durability and mass transport performance in practical PEM ECO2R. Substrate‐driven catalyst evolution is introduced as a key design principle for future CO2‐to‐formate energy systems.

Electrochemical CO2 reduction to formic acid enables sustainable carbon utilization, yet industrial deployment demands catalysts stable under realistic diluted feeds (10%–20% CO2) rather than laboratory‐standard pure CO2. We systematically compare electrodeposited Sn–Zn/C and Sn–Cu/C bimetallic cathodes in Proton Exchange Membrane electrolyzers under pure (100%) and diluted (50%) CO2 feeds, bridging the lab‐to‐industry gap. Under pure CO2, Sn–Zn/C achieves 40.81% Faradaic efficiency (FE) for formic acid versus 29.17% for Sn–Cu/C. Critically, under diluted CO2, Sn–Zn/C retains 42.7% activity (17.44% FE), while Sn–Cu/C completely deactivates (0% FE). Multimodal characterization (scanning electron microscopy‐energy‐dispersive X‐ray spectroscopy, X‐ray diffractometer, Brunauer‐Emmett‐Teller (BET), Fourier transform infrared, electrochemical impedance spectroscopy) reveals that Sn–Zn/C's superior performance stems from thermodynamically compatible SnO2/ZnO phases, which exhibit beneficial textural evolution (+61% surface area) and compositional stability (ΔSn = −0.95%, ΔZn = −2.62%). Conversely, Sn–Cu/C suffers phase instability (complete CuO loss), textural collapse (‐66% surface area), and severe compositional drift (ΔCu = −7.85%). This work demonstrates that pure CO2 testing alone cannot predict industrial viability and establishes design principles for practical CO2‐to‐formic acid catalysts: prioritize oxide phase compatibility, stable heterointerfaces, and robust textural properties. The findings expose the “purity bias” masking deactivation mechanisms and establish diluted‐feed testing as indispensable for bridging laboratory performance with real‐world electrochemical CO2 utilization.

The selective conversion of methane to methanol under mild conditions remains a major challenge due to the high stability of the C-H bond and the propensity for overoxidation. Herein, NiO/TiO2 photocatalysts were synthesized using both commercial nickel precursors and nickel recovered from spent Ni-Cd batteries, providing a sustainable pathway that integrates methane valorization with battery-metal recycling. The battery-derived catalysts PB1 and TB1 achieved methanol formation rates of 2.66 and 6.36 mmol g-1·h-1, respectively, comparable to those of the commercial counterparts PC1 (2.38 mmol g-1·h-1) and TC1 (7.31 mmol g-1·h-1), demonstrating that recycled nickel can effectively replace commercial nickel without performance loss. Synthesized TiO2-based catalysts consistently outperformed P25-based materials, and increasing Ni loading correlated positively with methanol formation rate, underscoring the importance of Ni-induced defect engineering. Structural and spectroscopic analyses confirmed preservation of the anatase phase alongside the formation of Ti3+ and oxygen vacancies, which suppressed electron-hole recombination. Density functional theory calculations revealed that methane activation proceeds via a low-barrier homolytic C-H cleavage pathway on Ni-O sites in the presence of surface hydroxyl species, stabilizing methyl intermediates and favoring selective methanol formation. Ultimately, the combined experimental and theoretical results establish recycled Ni-modified TiO2 as a sustainable and mechanistically rational photocatalyst for selective methane-to-methanol conversion.

Biodiesel is a renewable energy source that is utilized as a diesel blend B30 in Indonesia. However, biodiesel has the weakness that can induce microbiologically influenced corrosion phenomena, which poses a risk of material degradation and engineering failure on the carbon steel storage system. The objective of this study is to compare the influence of Pseudomonas sp. and mixed culture on biofilm formation, carbon steel corrosion, and fuel degradation within the B30 storage tank system, specifically at the oil-water interphase. This research shows that Pseudomonas sp. and mixed culture accelerate uniform corrosion rates with the value of 3.16 & times; 10-2 and 2.15 & times; 10-2 mm/year, respectively, higher than the control variation and the oil-phase corrosion variation from the previous research. Moreover, fuel degradation occurs in the acid number increase to 2.06 and 1.42 mg KOH/ g for Pseudomonas sp. and mixed culture, respectively, exceeding both the control variation and the standard limit. Biocorrosion phenomena (microbial growth and corrosion phenomena) are dominant in the water phase as opposed to the oil phase. Two layers formed in the metal surface, namely biofilm (upper part, consisting of water, protein, polysaccharides, and lipids) and corrosion products (lower part, consisting of iron oxides and iron phosphates). These findings indicate that microbial activity at the oil-water interphase plays a critical role in accelerating corrosion and fuel degradation, with Pseudomonas sp. exhibiting a more severe impact than mixed cultures. Future research should investigate the biocorrosion control, higher immersion time, pit depth measurement, and utilization of advanced analytical techniques to better predict and mitigate engineering failures in biodiesel-related systems.

Hydrogen is increasingly adopted as a low-carbon energy carrier, creating a need for rapid and auditable blast-consequence screening to inform hazard zoning. This study develops a web-based simulation platform that automates a transparent TNT-equivalent workflow from minimal inputs (inventory volume and evaluation distance). The platform converts volume to mass, estimates TNT-equivalent charge using an energy basis and efficiency factor, applies Hopkinson–Cranz cube-root scaling, and predicts peak side-on overpressure using three well-established empirical correlations (Crowl and Louvar, Alonso, and Sadovski) under harmonized assumptions, while exporting calculation logs for traceability. Validation uses a Type-IV high-pressure hydrogen vessel-burst dataset with measurements at 2–18 m. Over the sensor-intact 6–18 m window, the Alonso correlation achieves MAE 6.006 kPa with R² 0.999, whereas Crowl and Louvar and Sadovski correlations yield MAEs of 18.136 kPa and 17.164 kPa with R² of 0.985 and 0.993. A 50 kg TNT-equivalent Gangneung 2019 case gives 50.9–86.7 kPa at 15 m and 3.58–6.34 kPa at 100 m, consistent with reported steel deformation and widespread glazing damage. Overall, the platform enables transparent, traceable preliminary consequence estimation to support hazard-zoning decisions for hydrogen storage.

This study aims to investigate the synthesis of nanocarbon composites from natural activated carbon (ACN) and nanocarbons derived from acetylene black (AB), carbon nanotubes (CNTs), and graphene (GP). The process of synthesizing nanocarbon composites from natural activated carbon was carried out in two stages: mixing activated carbon with nanocarbons in a ball mill for 4 h, followed by ultrasonication at 65 degrees C for 1 h, and drying the composite product. The results of physical characterization showed that the composition of the natural activated carbon and nanocarbon decreased the degree of graphitization, surface area, and crystallinity of the nanocarbon composites. Electrochemical characterization revealed that the nanocarbon composite composition enhanced capacitance, improved rate capability, reduced cell resistance (including ohmic, charge-transfer, and diffusion), and increased supercapacitor cell-cycle stability. The highest capacitance of 229.2 F g-1 was achieved in a supercapacitor cell using the ACN/AB/CNT/GP composite. The rate capability of ACN/AB/CNT/GP composite-based supercapacitor cells is 89%. Results from the cycle stability analysis show the capacitance retention of 103% after 10,000 cycles. The carbon nanocomposite increased the energy density and power of the super-capacitor cells from 5.1 Wh kg-1 and 303.6 W kg-1 to 8 Wh kg-1 and 447.5 W kg-1, respectively.

Waste management remains one of the persistent global environmental challenges, particularly with the rise of modern manufacturing process. Synthetic dyes, such as methylene blue pose a significant threat to aquatic ecosystems due to their toxicity and potential to cause irritation. While biological treatment methods are suitable for biodegradable and non-toxic waste, they are ineffective against complex dye-containing effluents. To address this, advanced oxidation processes (AOPs) have been explored, with photocatalytic ozonation emerging as a promising approach by combining photocatalysis with catalytic ozonation to achieve faster reaction rates and higher degree of mineralization. In this study, MXene/TiO2 was selected for its ability to enhance charge separation and electron-hole pair formation under visible light irradiation. MXene was synthesized via in-situ etching using HF, followed by delamination, while the MXene/TiO2 composite was prepared through calcination treatment at various temperatures (150, 250, and 300 degrees C). Photocatalytic ozonation experiments were conducted using a batch top-down photoreactor equipped with a 500 W Xenon lamp. The results showed that the composite treated at the lowest calcination temperature (MT-150) exhibited the highest catalytic performance (0.0055 min-1 and 56.1%), outperforming MT-250 (0.0038 min-1 and 45.37%) and MT-300 (0.0024 min-1 and 33.75%). Although the commercial TiO2 demonstrated superior activity under UV light (0.0331 min-1 and 98.6%), MT-150 (0.0034 min-1 and 35.4%) and MT-250 (0.0022 min-1 and 21.1%) exhibited better photoactivity under visible light. However, structural analysis revealed that the MXene/TiO2 composite became increasingly amorphous due to agglomeration and structural degradation.

This work investigates synthesizing activated carbon obtained from rubber seed shells utilizing several activating agents (KOH, CaCl2, and ZnCl2) for supercapacitor applications. Activated carbon was produced from a rubber seed shell using hydrothermal carbonization at 275 °C for 60 minutes and a 120-minute activation treatment at 800 °C. Various activating agents pronounced impacted the pore architecture, surface area, crystallinity, and level of graphitization, which collectively determined the electrochemical characteristics of the resulting materials. Incorporating activation agents enhances the specific surface area and influences the extent of graphitization of activated carbon. The specific surface area of activated carbon products ranges from 367 to 735.2 m² g⁻¹. Further investigation through electrochemical analysis, conducted with a carefully engineered two-electrode system, demonstrated a peak electrode capacitance value of 246 F g-1 at 50 mA g-1 for an ACZn-based supercapacitor. Supercapacitor cells’ energy and power densities reached significant levels, measuring 5.47 Wh kg-1 and 246 W kg-1, respectively. The RSS-derived activated carbon-based supercapacitor exhibited remarkable longevity in a 5000-cycle test, with consistent capacitance retention and coulombic efficiency of 100.11% and 100%, respectively. This work presents a sustainable pathway for producing activated carbon electrodes, contributing to the global circular economy and demonstrating considerable industrial potential.

Microbial fuel cell (MFC) technology is a renewable energy solution that offers multiple benefits, including environmental friendliness, direct electricity generation, and wastewater treatment. In wastewater treatment, MFCs convert organic matter into electricity while simultaneously treating wastewater. This study investigated a double-chamber MFC using tofu wastewater and palm oil mill effluent (POME) as substrates. A carbon-based material served as the electrode in a membrane electrode assembly (MEA). The results revealed that the MFC generated voltages of 546 mV and 876 mV for tofu wastewater and POME, respectively. The highest power and current densities measured were 12.45 mW/m² and 25.87 mA/m² for tofu wastewater, and 25.22 mW/m² and 52.8 mA/m² for POME. Furthermore, the chemical oxygen demand (COD) removal efficiencies were 52.7% for tofu wastewater and 56.7% for POME. These findings demonstrate the potential of MFC technology for power generation using tofu wastewater and POME, making it a promising approach for sustainable energy and wastewater treatment.

Nanocarbon composites have emerged as a vanguard technology in energy conversion and storage, redefining the paradigms of battery, supercapacitor, and solar cell design. Researchers are orchestrating a paradigm shift in energy storage dynamics by leveraging the exceptional characteristics of materials such as graphite, fullerene, graphene, and carbon nanotubes. The intrinsic attributes of nanocarbon, including superior electrical conductivity, mechanical resilience, and expansive surface areas, delineate them as pivotal constituents for augmenting the performance metrics of energy storage and conversion devices. In the domain of batteries, nanocarbon composites engender heightened energy density, accelerated charge/discharge kinetics, and prolonged cycle life. Concurrently, their integration into supercapacitors begets augmented energy and power densities, facilitating swift energy transference and storage. These composites' malleable and lightweight nature introduces a transformative dimension, enabling the fabrication of compact, pliable, and highly efficient energy storage apparatus.

This study focuses on the development and performance evaluation of a Pressure Swing Adsorption (PSA) system utilizing molecular sieve Zeolite 13X for CO2 capture. A fixed-bed reactor was designed and simulated with Aspen Adsorption to optimise adsorption conditions. The system, tested with a 24.75 L/min gas feed (10% CO2, 90% N2) at 30 °C and 6 bar, operated cyclically every 7 minutes. Simulation results recommended a reactor volume of 4.9 L (ID 102 mm × T/T 600 mm). Sensitivity analysis showed that adsorption capacity declined as CO2 concentration increased, with CO2 uptake decreasing from 24.75 L/min at 10%-mol to 8.44 L/min at 70%-mol. Key design parameters such as feed flow rate, intraparticle voids, bulk density, and particle size were also evaluated. A prototype was built based on simulation results and tested, achieving a 120 s breakthrough time and an optimal 60 s swing interval over 17 cycles. This work supports the future integration of PSA-based CO2 capture with electrochemical CO2 reduction (ECO2R).

The utilization of biodiesel as fuel in Indonesia has reached B35 (a mixture of 35%-v biodiesel and 65%-v petrodiesel). The B35 storage system is designed from a carbon steel material with good mechanical properties. However, biodiesel has the weakness of being more polar, easily degraded, and more hygroscopic so it can induce biocorrosion and a decrease of B35 by microbial activity. This study aims to compare the influence of culture type interaction on biofilm formation, carbon steel corrosion, and fuel degradation in the B35 storage system. The experiment was carried out by immersing carbon steel ST-37 coupons in a B35 test medium for 21 days. The analysis consists of the biofilm morphology, growth of biofilm microbes, metal surface morphology, biofilm composition, corrosion products, fuel biodegradation, total acid number, and risk of tank damage. The results obtained that in each culture type, the growth of S. marcescens biofilm colonies was significantly lower than the growth of B. subtilis, P. aeruginosa, and M. luteus biofilm colonies. In addition, the mass loss of carbon steel tends to decrease as well as its corrosion rate although all culture type causes an increase in the acidity of B35 fuel beyond the specification.

Biodiesel’s low storage stability and hygroscopic properties make it a suitable environment for microorganisms to grow, leading to biocorrosion on metal and decreased fuel quality. One of the methods used in corrosion control is inhibitor addition. This study examines the application of several inhibitors (clove bud and Eucalyptus globulus essential oil as green biocorrosion inhibitor and glutaraldehyde as chemical biocorrosion inhibitor) on Pseudomonas sp. biofilm formation, ST-37 carbon steel corrosion, and B35 fuel quality in a biodiesel storage tank system. The results showed that glutaraldehyde 500 ppm has the best performance in inhibiting biofilm growth and the increase of total acid number. Additionally, clove bud essential oil at 5000 ppm has better performance in inhibiting biofilm growth rather than Eucalyptus globulus essential oil at the same concentration, particularly in the water phase. Meanwhile, Eucalyptus globulus essential oil at 5000 ppm has better performance in reducing the uniform corrosion rate and pitting formation rather than clove bud essential oil at 5000 ppm and glutaraldehyde at 500 ppm. However, both essential oils increase total acid number significantly. In the future, the influence of these essential oils as biocorrosion inhibitors in mixed culture, as well as their abilities in preventing electrochemical corrosion should be investigated.

Biodiesel is a renewable energy which can be blended with petrodiesel due to its similar properties. However, biodiesel has several weaknesses, such as being more hygroscopic, polar, and biodegradable, resulting in microbiologically influenced corrosion (MIC) in the storage system. While MIC has been widely reviewed, limited attention has been given to its occurrence in biodiesel-related systems, and this study addresses that gap as its main novelty. This review discusses recent studies on MIC in petrodiesel-biodiesel storage systems, focusing on mechanisms, research methods, and mitigation strategies, which can serve as a valuable reference for stakeholders aiming to deepen their understanding and guide further investigations in this field. Results show that the corrosion rates in the oil-water interphase (Moderate to Severe) are relatively higher than in the oil phase (Low to Moderate), with pitting corrosion being relatively higher than uniform corrosion. Recent studies have focused on a limited range of axenic cultures in the oil phase. Future studies should focus on the oil-water interphase and expand research parameters such as microbial cultures (axenic, consortium, and mixed cultures), higher biodiesel content blends (B40/B50) or biodiesel alternatives (green diesel) and environmental conditions (temperature, water content, etc.). Additionally, improving MIC detection and monitoring techniques as well as developing sustainable corrosion mitigation strategies will help industries mitigate economic losses, optimize storage systems, and support the global transition to higher biodiesel utilization.

The increasing concentration of CO2 in the atmosphere has contributed significantly to global warming and its associated environmental effects. Electrochemical conversion has emerged as a promising approach for CO2 capture, storage, and utilization to produce valueadded chemicals. However, the inherently low solubility of CO2 in aqueous solutions presents a major challenge to the efficiency of process. Unlike previous studies that focused on increasing CO2 solubility by lowering the temperature or using non-aqueous solvents, this work explores the use of smaller gas bubbles to enhance CO2 retention time in solution. The objective is to prolong the residence time of CO2 bubble in the electrolyte, allowing for gradual dissolution, sustained saturation, and improved interaction with the cathode surface. Under the same operating voltage, the bubble stone sparger, produces bubbles with diameters of 6.18 and 3.26-times than those generated by the atomizer and air stone, respectively, achieved 29.23% and 15.23% higher current efficiency. Similarly, the formic acid yield increased by 50.70% and 28.21%, compared to the other sparger types. The highest current efficiency (11.60%) and formic acid yield (0.122%) were obtained using the bubble stone sparger with a cathode length of 2.5 cm, a cathode-sparger distance of 0.5 cm, and an operating voltage of 6 V. These findings highlight the potential of using smaller bubble sizes to improve the electrochemical reduction of CO2 by enhancing gas-liquid interaction and mass transfer performance.

Industri minyak kelapa sawit menghasilkan limbah signifikan seperti POME yang dapat mencemari lingkungan jika tidak dikelola dengan baik. POME dapat merusak lingkungan terutama ekosistem perairan. Pengolahan POME penting untuk keberlanjutan industri ini. Advanced Oxidation Processes (AOPs), termasuk fotokatalitik, merupakan salah satu opsi teknologi yang dikembangkan untuk mendegradasi senyawa organik dalam limbah POME. Dalam studi ini, degradasi fotokatalitik limbah POME menggunakan katalis berbasis WO3 dengan menggunakan lampu Xenon 500 W menunjukkan bahwa metode ini efektif dalam mengurai limbah POME. Fotokatalis WO3 disintesis menggunakan metode hidrotermal pada temperatur 180, 200, 220, dan 240 °C, menghasilkan struktur kristal Hexagonal dan Orthorhombic, danTipe V mesopori. Penggunaan katalis WO3 dengan konsentrasi 1 g/L mampu mengurangi Chemical Oxygen Demand (COD) hingga 48,05%, degradasi warna hingga 36,22%, dengan konstanta laju reaksi COD sebesar 3,7×10-3 menit-1.

B30, which consisted of 30 %-v biodiesel and 70 %-v petrodiesel, is a renewable fuel that is being developed in Indonesia. In the B30 storage system, microbes utilize B30 and cause corrosion of carbon steel. This research aims to compare the interaction effect of consortium culture (S. marcescens - B. megaterium and S. marcescens - B. licheniformis) and mixed culture on the corrosion of carbon steel in the B30 storage system. The experiment was carried out by immersing carbon steel ST-37 specimens in B30 test medium for 21 days. Sample testing and analysis includes the number of microbial colonies, chemical bonds of biofilm composition, morphology of biofilms and metal surfaces, corrosion rate and corrosion products. The results shows that antagonistic interactions occurred in the consortium culture, resulting in the decrease of corrosion rate. Meanwhile, synergistic interaction occurred between the microbes in the mixed culture, resulting in higher corrosion rate. The corrosion mechanism that occurs in consortium culture and mixed culture involves the same electrochemical reactions.