Anh Son Hoang

In this study, the green synthesis of silver nanoparticles (AgNPs) was performed using S.nervosum leaf extract, and their physicochemical characterization was also studied. The characteristic surface plasmon resonance peak observed in the visible region at 435 nm is consistent with previous reports of silver nanoparticle formation. The synthesized AgNPs were also characterized by SEM, TEM, XRD, and FTIR, which revealed their nearly spherical shape, with a diameter mainly in the 10 - 30 nm range. The antimicrobial activity of AgNPs was studied using the agar well diffusion method on four clinically significant pathogenic microorganisms (P. aeruginosa ATCC 27853; E. coli ATCC 35218, S. aureus ATCC 12493; S. aureus Mastitis isolate). The results showed that the green-synthesized AgNPs exhibited antimicrobial activity at most studied concentrations, including the antibacterial effect against the S. Aureus (Mastitis isolate) strain, which was found to be resistant to Tetracycline at 100 µg/L. The antifungal activity of these nanoparticles was also studied on Colletotrichum gloeopsoriodes by colony formation assay. The green synthesis of AgNPs was successfully conducted for the first time using the aqueous extract of S. nervosum. The results of this study indicate that the silver nanoparticles have potential applications as antibacterial and antifungal agents.

In this study, the microwave heating efficiency of a water body is investigated with different shape factors. In particular, the same water volume was deposited in cylindrical containers with different diameters. Here, “shape factor” refers to the ratio between the surface fluid layer, which strongly absorbs microwave energy, and the inner layer, which is heated largely via conduction. For a liquid in a cylindrical container, the shape factor is characterised as the ratio between the depth and diameter of the air/water surface area. The heating efficiency is characterised by relating the energy absorbed in the outer fluid layer with the energy gained in the bulk and monitoring the temperature in the fluid bulk at the point that the outer layer commences boiling. A correlation equation for the uniformity of the sample heating (with stirring) provided a simple link between the physical factors and microwave (MW) parameters. It was found that a depth/diameter ratio approaching 1:1 provided the most uniform heating. The correlations between the fitting parameters and physical conditions provide a simple yet effective method to characterise the thermal homogeneity of microwave heating that can assist with practical parameterisation of the design of microwave reactors.

A powerful carbon-based solid acid catalyst and furfural were obtained from rice straw (RS) biomass resource. The acid catalyst was prepared through the carbonization and sulfonation of RS. Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, N2 adsorption-desorption, and ammonia temperature-programmed desorption (NH3-TPD) were used to characterize the catalysts. The effect of sulfonation time (4 h to 16 h) on the structure and acidity of the catalysts was elucidated. After 16 h of sulfonation, the BET surface area and the total acidity of the catalyst reached 415 m2/g and 7.48 mmol/g, respectively. Moreover, strong acid sites accounted for more than 63% of acidity. The catalyst was then used for the conversion of RS into furfural in water. The influence of reaction temperature and time while using the catalyst on the conversion process was also investigated. The catalyst exhibited high activity in the conversion of RS, with a furfural yield of 68.3 g/kg RS at 160 °C in 5 h.

Thickener, also known as a gelling agent, is a critical component of lubricating greases. The most critical property of thickener, temperature resistance, is determined by the molecular structure of the compounds. Currently, all high-temperature-resistant thickeners are based on 12-hydroxystearic acid, which is exclusively produced from castor oil. Since castor oil is also an important reagent for other processes, finding a sustainable alternative to 12-hydroxystearic acid has significant economic implications. This study synthesises an alternative thickener from abundant agricultural waste, cashew nut shell liquor (CNSL). The synthesis and separation procedure contains three steps: (i) forming and separating calcium anacardate by precipitation, (ii) forming and separating anacardic acid (iii) forming lithium anacardate. The obtained lithium anacardate can be used as a thickener for lubricating grease. It was found that the recovery of anacardic acid was around 80%. The optimal reaction temperature and time conditions for lithium anacardate were 100 °C and 1 h, respectively. The method provides an economical alternative to castor and other vegetable oils. The procedure presents a simple pathway to produce the precursor for the lubricating grease from agricultural waste. The first reaction step can be combined with the existing distillation of cashew nut shell processing. An effective application can promote CNSL to a sustainable feedstock for green chemistry. The process can also be combined with recycled lithium from the spent batteries to improve the sustainability of the battery industry.

In this study, green synthesis and physicochemical characterization of silver nanoparticles (AgNPs) using S.nervosum leaf extract. The characteristic surface plasmon resonance peak observed in the visible region at 435 nm is consistent with previous reports of silver nanoparticle formation. The synthesized AgNPs were also characterized by SEM, TEM, XRD, and FTIR, which reveal their nearly spherical shape, mainly in the 10–30 nm diameter. The antimicrobial activity of AgNPs was studied using the agar-well diffusion method on four clinically significant pathogenic microorganisms (P.aeruginosa ATCC 27853; E.coli ATCC 35218, S.aureus ATCC 12493; S.aureus Mastitis isolate). The results showed that the green synthesized AgNPs exhibited antimicrobial activity at most studied concentrations, including the antibacterial effect against S.aureus (Mastitis isolate) strain, which was found to be resistant to Tetracycline 100 µg/L. The antifungal activity of these nanoparticles was also studied on Colletotrichum gloeopsoriodes by colony formation assay. The green synthesis of silver nanoparticles (AgNPs) was successfully conducted for the first time utilizing the aqueous extract of S.nervosum. The results of this study indicate that silver nanoparticles have potential applications as antibacterial and antifungal agents.