Proton exchange membrane fuel cells (PEMFCs) have attracted significant attention due to their high efficiency and low emission characteristics. However, the cell performance is strongly influenced by operating conditions and membrane properties, which are difficult to investigate comprehensively by experimental approaches alone. This study develops a complete electrochemical model of a single PEM fuel cell in the MATLAB – Simulink environment based on the voltage loss mechanisms including the Nernst potential, activation overpotential, ohmic losses, and concentration losses. The model is employed to quantitatively investigate the effects of operating temperature, hydrogen partial pressure, oxygen partial pressure, and membrane thickness on the polarization characteristics (I – V curves) of the PEMFC. Simulation results indicate that increasing temperature significantly enhances activation kinetics and improves cell voltage, while elevated oxygen partial pressure yields the most pronounced performance improvement among gas parameters. Conversely, increasing membrane thickness leads to higher ohmic losses and voltage degradation, especially in the high –current – density regime. The proposed model provides an effective numerical tool for teaching, system analysis, and preliminary optimization of PEMFC operating conditions.

In recent years, water hyacinth (Eichhornia crassipes) has been widely recognized as an invasive aquatic plant that proliferates rapidly on rivers, canals, ponds, and lakes, obstructing waterway transportation, impeding water flow, and contributing to environmental degradation. Despite its abundance in large river systems such as the Bach Dang River in Thu Dau Mot City, Binh Duong Province, this biomass resource remains largely underutilized, leading to significant waste of natural materials and ongoing ecological challenges. This study proposes an eco-friendly alternative by transforming water hyacinth into handmade paper sheets with natural coloration, rustic aesthetic, and complete absence of harmful chemicals. The resulting products exhibit acceptable strength and surface quality, making them suitable for practical and decorative applications including coasters, shoe insoles, greeting cards, notebooks, biodegradable packaging, paper bags, and eco-handicraft items. Raw materials were collected directly from the Bach Dang River by a student research group. The research employed a combination of primary and secondary data collection methods, along with experimental, analytical, and synthesis approaches to develop and evaluate the manual paper-making process. The developed chemical-free production method successfully yielded durable paper sheets that are environmentally safe and biodegradable. The findings demonstrate the feasibility of converting an invasive plant into value-added sustainable products, thereby contributing to waste reduction, biomass reuse, and the promotion of green production practices. Although the study is preliminary and limited by manual processing, lack of mechanization, and absence of standardized quantitative testing (e.g., tensile strength, water absorption, and biodegradability under controlled conditions), it provides a promising foundation for further optimization and scale-up. Future research should focus on improving uniformity, enhancing mechanical properties through natural additives, and conducting comprehensive performance and life-cycle assessments to support practical commercialization and broader environmental impact

MnO2 has the advantage of being environmentally friendly and abundant in soil, but its ability to activate persulfate is poor. This study combines MnO2 with CuO into a mixed metal oxide through a one-step reaction to increase the persulfate activation efficiency of the obtained product. These mixed oxides were synthesized by alkalization of a solution containing ions of two metals and then calcined at 300°C. The obtained oxide catalysts were characterized by methods such as FTIR, SEM, BET analysis, and zeta potential. The adsorption and decomposition of methyl orange (MO) were experimentally conducted in batch form using the above mixed metal oxides as adsorbents or persulfate activators. The results showed that the mixed oxides exhibited characteristic peaks in the FTIR spectrum, and were in the form of nanorods (CuO) and amorphous small particles (3:1CuO/MnO2). The CuO catalyst has a specific surface area of 20.23m²/g and pore sizes ranging from 20 to 30Å. The zeta potentials of both CuO and MO were highly negative, e.g., -46.5mV and -24.1mV, respectively. The adsorption capacities of MO onto the mixed oxides were quite low (~13.5%) and decreased gradually as the CuO content decreased. However, the persulfate activation capacity of the mixed oxides for MO decomposition was quite high, e.g., that of 3:1CuO/MnO2 for 40mg/L MO was 74.1%. In addition, the decomposition of MO almost followed pseudo-second-order reaction kinetics.

In this paper, Mn-Fe bimetallic nanoparticles were synthesized by simultaneous reduction of a salt mixture of KMnO4 and FeCl3 with glucose as a reducing agent. Degradation of methyl orange in aqueous solution, using hydrogen peroxide as an oxidizing agent, was used to evaluate the catalytic activity of the material. The material was characterized using scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The results showed that cubic manganese oxide nanoparticles were formed at the molar ratio of KMnO4/C6H12O6·H2O = 5/5 and the hydrothermal temperature of 120-220°C, while the oval-shaped structure was formed at the molar ratio of KMnO4/C6H12O6·H2O = 5/40 and the hydrothermal temperature of 220 °C. The cubic Mn-Fe bimetallic nanoparticle was still formed at the molar ratio of Mn/Fe/C6H12O6 = 5/2/5 and the hydrothermal temperature of 120°C, and the methyl orange decomposition efficiency was found to be the highest value of 57% on this catalyst sample.