The study investigated the use of CeO₂ extracted from monazite with calcium oxide (CaO) as a solid catalyst for biodiesel production. The wet impregnation method was used to produce CaO@CeO₂ mixed-oxide catalysts with 0–50 wt.% CaO. X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, thermogravimetric analysis (TGA), and a Fourier transform infrared spectrometer (FTIR) was used to characterize the catalysts. In order to determine the optimal preparation conditions, the effect of different CaO compositions on the performance of CaO@CeO₂ mixed-oxide catalysts was examined. The catalytic activity of the CaO@CeO₂ catalyst for the transesterification reaction of palm oil to produce biodiesel was studied. The results show that the optimum yield of biodiesel can reach 97% fatty acid methyl ester over the 30CaO@CeO₂ catalyst at the reaction conditions of 5 wt.% catalysts, methanol-to-oil molar ratio of 9:1, with a reaction temperature of 65 °C within 30 min. The results show that the high catalytic activity and stability of the CaO@CeO₂ catalyst make it a promising candidate for industrial-scale biodiesel production. Further study is needed to improve the stability and efficiency of catalysts in transesterification reactions to achieve a high FAME yield using long-life-span catalysts. Moreover, it is necessary to investigate the economic feasibility of this process for application in large-scale biodiesel production.

This study reports the mass concentrations, elemental characterization and identification of the possible sources of PM_2.5 and PM₁₀ at a suburban site in Pathum Thani, Thailand. The sampling was done from 18 February 2021 to 14 September 2021. PM_2.5 concentrations were between 0.39 μg/m³ and 174.26 μg/m³, while PM₁₀ concentration ranged from 12.75 μg/m³ to 242.02 μg/m³. The average concentration of PM_2.5 in the wet season (61.96 μg/m³) in the study area exceeded the national ambient air quality standards (NAAQS). Particle-induced X-ray emission (PIXE) was used to measure the element concentrations. The main elements, namely Fe, K, Cr and Ca, in both PM_2.5 and PM₁₀ showed significantly higher concentrations in the summer season. A qualitative inter-elemental correlation analysis, principal component analysis (PCA) and cluster analysis (CA) were applied for source identification of PM_2.5 and PM₁₀. The results for the three procedures were in good agreement. Four and three factors of sources were isolated by the PCA for PM_2.5 and PM₁₀, respectively. The main sources identified by PCA were, for PM_2.5, soil dust and biomass burning (32%), road dust and industrial emission (25%), vehicle and industrial emission (10%) and soil dust (9%); for PM₁₀, road dust and industrial emission (36%), crustal and biomass burning (30%) and industrial sources (10%).

The Thai domestic rare earth oxides, including cerium, lanthanum, and neodymium oxides, with the effects of calcination temperatures (500–1000 °C), were utilized as catalysts for twelve Jatropha biodiesel alternatives via an esterification reaction. This study applied life cycle assessment (LCA) methodology from well-to-wheel analysis to assess energy efficiency and the global warming impact with and without land use change. The results of the life cycle analysis showed that the Jatropha biodiesel alternatives using the La₂O₃ catalyst in all conditions (0.89–1.06) were found to be potential fuel substitutes for conventional diesel (0.86) in terms of net energy ratios; however, the results showed that they generated a higher global warming impact. Considering the improvement process of Jatropha biodiesel in the utilization of waste heat recovery, the Jatropha biodiesel reduced the impacts of the net energy ratios and the global warming impact by 22–24% and 34–36%, respectively. The alternative Jatropha biodiesel using the La₂O₃ catalyst with a calcination temperature of 600 °C was shown to be the most environmentally friendly of all the studied fuels; relatively, it had the highest energy ratios of 1.06–1.37 (with and without waste heat recovery) and the lowest total global warming impact of 47.9–70.7 kg CO₂ equivalent (with land use change). The integration of the material and process development by domestic catalysts and the recovery of waste heat would improve the sustainability choices of biofuel production from renewable resources for transportation fuels in Thailand.

The flow stress behavior of high-strength low-alloy (HSLA) steel at different true strains was studied using a hot compression test. The effect of dynamic recrystallization (DRX) on the transformed ferrite microstructures was investigated with electron backscatter diffraction (EBSD). The EBSD analysis indicated that the fraction of high-angle grain boundaries (HAGBs) and DRX increased with increasing true strain. The low-angle grain boundaries (LAGBs) were gradually transformed into HAGBs with increasing DRX degree. When the true strain was increased to 0.916, the fraction of HAGBs increased to 85% and the fraction of DRX increased to 80.3%. The relatively high fraction of HAGBs was related to the complete DRX. The dislocations and substructures in the tested steel at different true strains were characterized by transmission electron microscopy (TEM). TEM observation shows that the nucleation of the dynamically recrystallized grains occurred by the bulging of the original grain boundaries. The DRX nucleation mechanism of the HSLA steel is the strain-induced grain boundary migration mechanism.

Activated carbons (ACs) are a versatile group of adsorbents for water pollution control, especially organic dyes. Harsh chemicals and high temperatures are required for the activation process of ACs, which becomes a significant concern due to their toxicity and harmful effects on human health and the environment. Gamma irradiation, an alternative green technique, is a promising strategy for pretreatment and escalates the nitrogen or oxygen functional group of ACs. The current study provides the modification of ACs by the gamma irradiation in the various pH (5-11) of urea solution. The modified ACs were characterized by scanning electron microscopy (SEM), nitrogen gas adsorption-desorption analysts (BET), temperature program desorption (TPD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray diffraction spectroscopy (XRD). The point of zero charges and dye adsorption capacities were determined. This finding demonstrates that the ACs can be modified by gamma irradiation at 25 kGy in the urea solution media. The degree of graphitization enhanced significantly at pH 11(AC-pH11). The oxygen-rich functional groups created by radiation assists could enhance the electrostatic attraction between acid gases or cationic dyes. AC-pH11 also was able to adsorb methylene blue (160.73 ± 1.70 mg/g) greater than methyl orange (127.57 ± 2.22 mg/g).