Doonyapong Wongsawaeng

Ultra-high-molecular-weight polyethylene is a common choice for wear-resistant applications due to its low friction, high toughness, and chemical stability. However, its chemical inertness and low surface energy limit the adhesion of functional coatings such as graphene nanoplatelets (GNPs). In this study, chromic acid etching and plasma-functionalized GNP coating were used to improve the interfacial adhesion and tribological performance of UHMWPE. Substrates of UHMWPE were etched in chromic acid for 0, 5, 10, and 15 min and then dip-coated with argon plasma-treated GNPs. Etching time significantly impacted surface morphology, coating stability, wettability, and friction behavior. Moderate surface roughness, mechanical interlocking, and homogeneity of the GNP coating were obtained for the 5 min etching condition. This condition achieved the best tribological performance, with the coefficient of friction decreasing to 0.23 and the water contact angle decreasing to 88.17°. Mechanical testing showed that the 5 min etched sample kept most of its bulk properties, with a tensile modulus of 512.8 MPa, tensile strength of 27.71 MPa, and hardness of 67 Shore D. Longer etch times led to over-roughening and generation of micro-defects, causing lower coating uniformity and higher friction. This study shows the potential of controlled chromic acid etching with plasma-functionalized GNP coating to enhance the surface adhesion and tribological characteristics of UHMWPE, and mechanical properties were largely retained.

Enhancing biodiesel quality to enable higher blending ratios is essential for decarbonizing the transportation sector. This study investigates partial hydrogenation of soybean oil methyl esters in continuous flow over MCM‐41‐supported metallic Ni and nickel compound catalysts (carbide, nitride, phosphide, and sulfide). The fuel properties and fatty acid methyl ester (FAME) composition were thoroughly evaluated before and after the hydrogenation process. The hydrogenation activities were ranked as follows: NiC > NiN > Ni > NiS >> NiP. Although NiC showed the highest activity and improved oxidative stability, it lacked selectivity toward cis ‐C18:1, promoting trans ‐C18:1 formation and increasing the cloud point to 20 °C, rendering the product off‐specification. In contrast, NiS achieved a superior balance between activity and selectivity, increasing oxidative stability to 4.2 h while maintaining favorable cold‐flow properties. Moreover, NiS preserved activity and product selectivity over 24 h on stream, highlighting its promise for selective biodiesel upgrading under mild conditions.

A predictive gate-to-gate life cycle assessment (LCA) of plasma-assisted ammonia synthesis at TRL 4 is presented according to ISO 14040/44 standards. General plasma-assisted synthesis was evaluated through a mini-review‚ sensitivity analysis‚ and predictive LCA. The specific DBD needle-to-plate configuration LCA is performed using previously published experimental data. Two distinct scenarios were investigated. In the literature-based baseline scenario derived from sensitivity analysis, electricity consumption was 533 kWh/kg NH₃, giving a carbon footprint of 26.65–639.60 kg CO₂-eq/kg NH₃; electricity contributed 98.5% of total emissions, and impacts remained about 2.05 times higher than conventional Haber–Bosch. In contrast, the experimental DBD case study required 63,450 kWh/kg NH₃, showing reactor efficiency as the dominant driver of environmental performance. The BCS (≈1.39 kWh/kg NH₃) suggests that optimized plasma systems could potentially surpass conventional ammonia synthesis in energy efficiency. The environmental performance of plasma-assisted ammonia synthesis is affected by NH₃, NO_x, N₂O, and hydrogen emissions due to impacts on climate, air quality, water systems, and biodiversity. Future improvements may come from reactor and electrode optimization, catalyst integration, alternative plasma sources, and better process and heat integration, although deployment will likely depend on major efficiency gains and may be limited to niche decentralized applications.

The dehydrogenation of waste glycerol (GLY) to high‐value dihydroxyacetone (DHA) presents a sustainable valorization strategy through the application of dielectric barrier discharge (DBD) plasma technology. This study utilized multiple needle‐in‐tube configurations to evaluate efficiency under atmospheric pressure and ambient temperature, aiming for a high DHA yield. Key parameters, such as working gas type, gas flow rate, plasma input power, initial GLY concentration, and reaction time, were analyzed for their effects on GLY conversion, DHA yield, and DHA selectivity. Experimental results demonstrated a maximum DHA yield of 27.2% with a corresponding selectivity of 42%, while excessive OH• radical concentrations were found to adversely affect DHA formation through competing oxidation pathways. A comprehensive techno‐economic analysis confirmed the process’s technical feasibility and economic viability, demonstrating profitability within ± 20% market price fluctuations and a discounted payback period (DPP) of under 5 years. This research establishes an innovative pathway for sustainable waste‐to‐value conversion, demonstrating the potential of plasma dehydrogenation for optimized DHA production while contributing to circular economy principles through effective waste GLY utilization.

Rambutan seed waste from fruit processing remains underutilized, while conventional biodiesel routes face high feedstock costs and food-versus-fuel concerns. This study investigated a novel catalyst-free process for biodiesel production from rambutan seed waste using supercritical ethanol and ethyl acetate as renewable reactants to valorize fruit by-products. Batch reactions on the semi-solid fraction of rambutan seed oil (RSO) were conducted at 15 MPa to evaluate the effects of temperature (275–375 °C), reactant-to-oil molar ratio (20:1–40:1), and reaction time (15–50 min) on fatty acid ethyl ester (FAEE) yield. Under optimal conditions, FAEE yields of 59.92 and 41.92% were obtained using ethanol (350 °C, 40:1, 30 min) and ethyl acetate (350 °C, 30:1, 40 min), respectively. However, severe conditions degraded unsaturated esters, revealing a conversion–stability trade-off. The ethanol system exhibited faster reaction kinetics and lower activation energy than ethyl acetate. Applying the optimized ethanol-based conditions to the liquid fraction of RSO, which contained a lower proportion of saturated fatty acids, resulted in a markedly improved FAEE yield of 94.16%. This study demonstrated a catalyst-free supercritical route for converting rambutan seed waste into biodiesel, advancing waste-to-energy strategies and circular bioeconomy.

This work aims to study the enhancement of tribological, mechanical, and electrical properties of ultra-high molecular weight polyethylene (UHMWPE) via surface modification using graphene nanoplatelet (GNP) coating and electron beam irradiation.

Ammonia is an important chemical that is primarily used as fertilizer in agriculture. In a simple plasma reactor with water and nitrogen gas as the feed, the synthesis of ammonia was observed to have better reaction conditions than the Haber–Bosch process. The needle-to-plate type of the DBD plasma reactor was built from a borosilicate glass container with a single needle electrode covered by a quartz tube. In this study, the highest concentration of ammonia, measuring 19.7 ppm, was achieved at the reaction condition of 1.4 L/min N₂ flow rate, 75 W input power, 1 cm electrode gap size, and 30 min reaction time. The water type was DI water, with a pH value of 5. The UV light addition did not increase ammonia production as it promoted ammonia decomposition instead of formation. The constructed DBD plasma can be used for ammonia production. It is a simple and environmentally friendly process because it requires low input energy and can be operated at ambient conditions.