Lemongrass is a plant that contains aromatic compounds (myrcene and limonene), powerful deodorants, and antimicrobial compounds (citral and geraniol). Identifying a suitable drying model for the material is crucial for establishing an initial step for the development of dried products. Convection drying is a commonly used drying method that could extend the shelf life of the product. In this study, a suitable kinetic model for the drying process was determined by fitting moisture data corresponding to four different temperature levels: 50, 55, 60 and 65 °C. In addition, the effect of drying temperature on the moisture removal rate, the effective diffusion coefficient and activation energy were also estimated. The results showed that time for moisture removal increases proportionally with the air-drying temperature, and that the Weibull model is the most suitable model for describing the drying process. The effective diffusion coefficient ranges from 7.64 × 10⁻¹¹ m²/s to 1.48 × 10⁻¹⁰ m²/s and the activation energy was 38.34 kJ/mol. The activation energy for lemongrass evaporation is relatively high, suggesting that more energy is needed to separate moisture from the material by drying.

The purpose of this study was to attempt the encapsulation of lemongrass (Cymbopogon citratus) essential oil utilizing spray drying technique. An array of process parameters including concentration of wall (15–30%), type of wall materials (maltodextrin, maltodextrin and gum Arabic mixture), and concentration of essential oil (0.5–2.0%) were thoroughly investigated. The results show that the use of sole maltodextrin as encapsulant gave microcapsules characteristics comparable to that of powder produced using maltodextrin and gum Arabic mixture. The encapsulation process that was performed with maltodextrin at the concentration of 30% as wall material and lemongrass essential oil at the concentration of 1.5% as core material showed highest drying yield (84.49%), microencapsulation yield (89.31%) and microencapsulation efficiency (84.75%). Encapsulated essential oils retained most of their major constituents in comparison with the bare essential oils without any significant compromise in product quality.

Hospital wastewater contains pharmaceutical residues, chemicals, and pathogens that cause coloration and nourish pathogenic microorganisms. The objective of the study was to evaluate the effectiveness of a medical wastewater treatment system at Military Hospital 175 (Ho Chi Minh City, Vietnam) that combined a membrane bioreactor (MBR) system with nanofiltration (NF). The influent of the system was the wastewater discharged from the operating rooms of the hospital. The system has a capacity of 50 L/day and operates at three organic load rates (OLR) of 0.5, 1.5 and 2.5 kgCOD/m³day (COD: Chemical oxygen demand), in which each load rate operates for 40 days. The results showed that most nutritional criteria generally achieved positive results. Specifically, the average COD removal was shown to be consistently high throughout the three phases at 94%, 93.3%, and 92.7%, respectively. For removal of nitrogen, the system demonstrated efficiencies of 75%, 79%, and 83%, respectively, to three phases. The log removal value (LRV) for Escherichia coli and coliform bacteria were higher than four throughout the study period. The average removal efficiency for color and total iron was approximately 98% and 99%, respectively. The water quality after treatment, especially after NF, meets the Vietnamese standard of grade A. The arrangement in which the MBR preceded NF was also found to limit the amount of soil and solids entering subsequent treatment, which therefore improved the efficiency of NF, as demonstrated by the stability of post-NF transmembrane pressures throughout three cycles renewed by two backwashes.

N-[[1-[(4-fluorophenyl)methyl]-1H-indazol-3-yl]carbonyl]-L-valine, methyl ester (FUB-AMB) is the most recent psychoactive substance in Vietnam. FUB-AMB is a synthetic cannabinoid (SC) with has similar biological effects to tetrahydrocannabinol (THC), the main active component of natural cannabis. The previous study exhibits a harmful SC compound, which may cause many threatening to consumer health and social security due to the intensive effect of this compound on the mental status and behavior of the consumer. In this study, FUB-AMB was isolated the first time in Vietnam (1 g) with a purity of 98.34% (determined by High Performance Liquid Chromatography). Spectroscopic data (ultraviolet, infraRed 1Hydro - nuclear magnetic resonance, 13carbon - nuclear magnetic resonance) confirmed the structure of that isolated compound. The isolated FUB-AMB was used as a reference standard to develop an analytical method to detect drugs in the general marijuana group. Chromatography separation was achieved using a diphenyl dimethyl polysiloxane Gas chromatography (GC) column (30m×0.25mm×0.25µm) with a total run time of 10 minutes. The limits of detection and quantification for FUB-AMB was 0.15 μg/mL and 0.5 μg/mL, respectively. The developed method was used to detect FUB-AMB in synthetic cannabinoids in 30 samples. The results showed that the content of FUB-AMB ranged from 3.4-59.2 mg/g in 30 synthetic cannabinoids. The advanced GC-MS method is simple, sensitive, accurate and practically useful for the determination of FUB-AMB in synthetic cannabinoids, which supports the authorities’ crime handling.