Hue University Journal of Science: Natural Science

Green synthesis of silver nanoparticles using carbon quantum dots

Thi Hoa Le — 2025-03-24

Carbon quantum dots (CQDs), synthesized from betle leaves collected in Hue City, were used as both a reducing agent and a protective agent to synthesize silver nanoparticles (AgNPs). This is a "green synthesis" method, which is environmentally friendly, simple and highly effective. The factors affecting the formation of composite materials were investigated. The CQDs material has a size of about 5 nm, and the silver material on the CQDs (AgNPs/CQDs) has a UV-Vis absorption peak in the wavelength range of 400–440 nm, a size of about 30 nm and is stable for about 15 days of storage.

Adsorption of Co(II) from aqueous solutions onto Na-bentonite

My Linh Nguyen Le — 2025-03-19

In this work, Na-bentonite was characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and nitrogen adsorption/desorption. Na-bentonite was used for the removal of Co(II) from aqueous solutions. Co(II) adsorption follows the pseudo-first-order kinetic model. The equilibrium data were analyzed based on the Langmuir and Freundlich adsorption isotherm models. The highest monolayer adsorption capacity for Co(II) at 303 K derived from the Langmuir equation is 25.25 mg/g on Na-bentonite. The obtained thermodynamic parameters demonstrate that the adsorption is spontaneous (∆G° < 0) and endothermic (∆H° > 0), with increased entropy (∆S° > 0) in the investigated temperature range.

Effect of extraction temperature on content and in vitro antioxidant activity of polysaccharide from Gymnopetalum cochinchinense

Lan Huong Hoang Thi — 2025-03-19

The effect of extraction temperature on the in vitro antioxidant activity of polysaccharides from Gymnopetalum cochinchinense was investigated. The results show that at an extraction temperature of 80 °C, the antioxidant activity of the polysaccharides was the highest. The total antioxidant capacity of the PS-W-T80 sample was 0.2726 ± 0.0003 mg GA/g or 0.1776 ± 0.0001 mg AS/g. Furthermore, its IC₅₀ values in the DPPH and ABTS radical scavenging models were 0.83 and 3.30 mg/mL, respectively. Fourier transform infrared spectroscopy analysis indicates that the polysaccharides in the PS-W-T80 sample exhibit characteristic absorption peaks commonly found in polysaccharide structures. The average molecular weight of the extracted polysaccharide is approximately 5.56 × 10⁴ Da. These results show that the polysaccharide in PS-W-T80 from G. cochinchinense is a potential antioxidant agent.

Rambutan (Nephelium lappaceum L.) seed oil: extraction and application in food

Nguyen Kim Dong — 2025-03-19

The extraction of oil from rambutan seeds and applying oil to food was carried out at a laboratory scale to provide data and factual information about a new type of oil. This paper investigated the influence of the extraction methods (stirring, soxhlet, and ultrasonic), extraction solvent (ethanol and n-hexane), and extraction time (3, 5, 7, and 9 hours) on the extraction efficiency. The oil was applied to produce potato chips. The results show that the highest oil recovery efficiency was 37.7% when using the soxhlet method, n-hexane, and an extraction time of 9 hours. The frying oil temperature affected the colour (L, a, b, ∆E) of the potato chips. When the temperature increased, the values of L and ∆E decreased, whereas the values of a and b increased. In addition, the frying oil temperature has an influence on the smell, taste, and texture of the product. The optimal frying temperature for processing potato chips with good quality was 160 °C. The results of this study show that using by-products from rambutan to create a new kind of oil can satisfy consumers’ needs and diversify the products in the market.

Synthesis of nano zinc oxide by using hydrothermal method and its effect on germination ability of chestnut seeds (Castanea mollissima)

Giang Nam Nguyen — 2025-03-19

The traditional use of large quantities of fertilizers causes tremendous consequences to the environment. In this context, nanotechnology emerges as a new direction for sustainable and environmentally friendly agriculture. Zinc oxide nanoparticles (ZnO) are widely used in various fields, such as medicine or electronics. Several studies indicate that nano ZnO may be considered a potential nanofertilizer. Its administration in the early sowing stages, i.e., seed priming, proved to be effective in improving the germination rate, seedling and plant growth, and ameliorating the indicators of the plants. In this study, we synthesized ZnO nanoparticles by using the hydrothermal method. Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-vis spectroscopy were used to analyze the structure of the obtained ZnO nanoparticles. The results show that ZnO nanoparticles are spherical, with diameters ranging from 11.379 to 23.729 nm. These ZnO nanoparticles were used in the germination and root stimulation of chestnut seeds (Castanea mollissimab). The experiments show that these nanoparticles significantly improved the germination rate and root growth of chestnut seeds.

Synthesis of nano cobalt ferrite by using starch-assisted hydrothermal method

Chau Ngoc Anh Vo — 2025-03-19

In this article, a synthesis of cobalt ferrite/carbonized starch from nitrate salt and starch precursors by using the hydrothermal method at different temperatures is presented. The products were characterized by using X-ray diffraction, transmission electron microscopy, vibrating sample magnetometer, nitrogen adsorption/desorption isotherms, and thermal analysis. The results show that the obtained material has a large specific surface area (85.2 m²/g) and nano-sized particles with diameters of about 10–15 nm. Cobalt ferrite, with superparamagnetic properties and high magnetic saturation, has catalytic photodegradation activity and decomposes methylene blue. This material can be recovered when placed in a magnetic field. These results open up the possibility of applying nano cobalt ferrite in environmental treatment.

Growth potential of Rhodopseudomonas sp. bacterium in various organic carbon sources and its application in aquaculture wastewater treatment

Le Van Tuan — 2024-12-31

This study assesses the growth potential and aquaculture wastewater treatment capabilities of the photosynthetic bacterium Rhodopseudomonas sp., isolated from coastal areas of Thua Thien Hue province. The bacterium’s growth ability was tested with various organic carbon sources, including sodium acetate, sucrose, and glucose, and examined under both sterilized and non-sterilized aquaculture wastewater conditions. The results show that Rhodopseudomonas sp. achieved a high chemical oxygen demand (COD) removal efficiency, reducing COD by 73% in sterilized wastewater and 56% in non-sterilized wastewater after 12 days. The bacterium also effectively removed up to 90% of total ammonium nitrogen and 71% of phosphate (P-PO₄³⁻) in non-sterilized wastewater. Rhodopseudomonas sp. exhibited stable growth in high-salinity environments (20‰) and flexibility in utilizing various carbon sources, demonstrating its potential for sustainable aquaculture wastewater treatment (WWT), minimizing environmental pollution, and preserving natural ecosystems. This study not only contributes to developing sustainable WWT methods but also highlights the practical application of native Rhodopseudomonas sp. bacteria in aquaculture and other high-salinity industrial wastewater systems.

Isolation and quantification of major saponin ginsenoside Re from hairy root cultures of Panax vietnamensis Ha et Grushv by HPLC

Tuan Vu Van — 2025-03-19

From the 80% ethanol extract of the hairy root cultures of Panax vietnamensis, a main dammarane-type saponin was isolated by using the chromatographic method. The isolate was identified as ginsenoside Re (1) via an extensive analysis by using NMR and MS, as well as comparison with published data. A quantitative procedure using HPLC with a UV detector has been developed to determine the ginsenoside Re content from the hairy roots of cultured P. vietnamensis, and the procedure was also validated according to the ICH guidelines in terms of accuracy, repeatability, linearity, and selectivity. The determination was carried out by using a C18 Shimadzu Shim-pack GIST (4.6 × 250 mm; 5 µm) column as a stationary phase with a gradient solvent system of acetonitrile-water as eluant. The flow rate was set at 1.0 mL/min and UV detection at 196 nm. This is the first report on the isolation and quantitative analysis of ginsenoside Re in the samples of P. vietnamensis hairy roots.

A kinetics study of diffusion-adsorption of antibiotics chloramphenicol, tinidazole, and ofloxacine, and anti-inflammatory agent piroxicam at MnO2/ErGO and AgNPs/MnO2/ErGO-modified glassy-carbon electrode

Xuan Anh Vu Ho — 2025-03-19

A glassy carbon (GC) electrode was modified with MnO₂/GO and AgNPs/MnO₂/GO composite materials. After electrochemical reduction, the reduced MnO₂/ErGO and AgNPs/MnO₂/ErGO materials exhibited large electrochemical active surface areas of 0.079 cm² and 0.087 cm², respectively; the charge transfer resistance (R_ct) was relatively small, at 0.188 kΩ and 0.077 kΩ, respectively. In this study, two antibiotics, namely chloramphenicol (CAP) and tinidazole (TNZ) were adsorbed onto the surface of MnO₂/ErGO-GCE, and the antibiotic ofloxacine (OFX) was adsorbed onto the surface of AgNPs/MnO₂/ErGO-GCE. The results show that the adsorption process took place within 3 minutes and followed a pseudo-second-order kinetic model with saturation adsorption capacities of 1,310.16, 1,873.41, and 1,140.93 mg.g^-1, respectively. For the anti-inflammatory drug piroxicam (PRX), the diffusion process across the solution – AgNPs/MnO₂/ErGO-GCE electrode interface was more dominant than the adsorption process, with the diffusion process occurring rapidly within less than 30 s. This study provides further insights into the mechanism of the diffusion-adsorption processes of antibiotics and anti-inflammatory agents on electrode-modified surfaces.

Simultaneous detection of paracetamol, chlorpheniramine maleate, cinnarizine, loratadine, and cetirizine hydrochloride in preparations derived from medicinal herbs by using high-performance liquid chromatography

Hai Phong Nguyen — 2025-03-19

This study was conducted to develop a method for simultaneous quantification of paracetamol (PAR), chlorpheniramine maleate (CPM), cinnarizine (CET), loratadine (LOR), and cetirizine hydrochloride (CIN) in preparations derived from medicinal herbs by using high-performance liquid chromatography (HPLC) with a PDA detector. The analytical method was performed under the following chromatographic conditions: InertSustainTM C18 column (250 mm × 4.6 mm, 5 μm); mobile phase: a mixture of ACN (A) and 5 mM NaH₂PO₄ (pH = 2.3) (B) according to a gradient program; flow rate: 1.0 mL/min; sample injection volume: 20 μL; column temperature: 40 °C; detection wavelength: 245 nm for Paracetamol, 225 nm for chlorpheniramine maleate, 230 nm for cetirizine hydrochloride, 254 nm for loratadine, and 253 nm for cinarizin. The analytical method was validated according to ICH and AOAC guidelines. The detection limits of PAR, CPM, CET, LOR, and CIN were 2.00, 2.00, 1.75, 1.00, and 0.50 µg/mL, respectively. The developed procedure was applied to analyze 32 samples of traditional medicinal products collected from the local markets.

Synthesis of Cr(III)-terephthalate metal-organic framework and its application to modify electrodes for electrochemical analysis of paracetamol

Ngoc Nghia Nguyen — 2025-03-19

This study describes the synthesis of a metal-organic framework material MIL (Materials Institute Lavoisier) by using the hydrothermal method. The obtained materials were characterized with X-ray diffraction and scanning electron microscopy. The study shows that MIL-101 was formed at an early stage of synthesis (8 h), and then the phase transformation of the material occurred when the reaction time was extended to 48 h. The octahedral morphology of MIL-101 changed to a rod-like shape when the hydrothermal time increased. An electrode modified with MIL-101 exhibited more satisfied electrochemical properties towards paracetamol than other electrodes via cyclic voltammetry measurements. The differential pulse voltammetry measurements show a high linearity between peak currents and PCT concentration in the concentration range of 0.50–6.95 µM with a detection limit of 0.68 µM.

Optimizing the extraction process of paracetamol and chlorpheniramine maleate mixed in herb products

Thi Cam Minh Dao — 2025-03-19

In this study, we optimised the extraction procedure for paracetamol and chlorpheniramine maleate by using the response surface method with the Box-Behnken model. The influencing factors are ethanol concentration, extraction time, and liquid-to-solid ratio. The optimal extraction conditions for paracetamol and chlorpheniramine maleate mixed in medicinal herbs are as follows: ethanol concentration 96%; extraction time 14.04 minutes; liquid/ solid ratio 51.41 mL/g. Under these optimal conditions, the extraction efficiency of paracetamol and chlorpheniramine maleate is 98.10 and 95.64%, respectively. The optimization results were experimentally verified, showing a close agreement with the predicted model.

Synthesis of Cu/diatomite composite and its catalytic activity via phenol oxidation in aqueous solutions

Dinh Du Pham — 2025-03-19

In this paper, Cu/diatomite composites were synthesised by dispersing copper ions onto the diatomite surface via the hydrolysis reaction of copper(II) nitrate trihydrate salt in water. The effects of reaction temperature and time on the catalytic activity of the obtained composite were investigated. The material was characterised by using energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and nitrogen adsorption-desorption isotherms. Under optimal conditions, the obtained Cu/diatomite composite with a specific surface area of 44.7 m²/g contained about 0.91% Cu (wt.%), highly dispersed on the diatomite matrix. The decomposition reaction of phenol in an aqueous solution with hydrogen peroxide was used to evaluate the catalytic activity of the material. Phenol conversion was 94% under the following conditions: reaction time 240 min, temperature 50 °C, phenol concentration 1000 mg/L, Cu/diatomite 1 g/L, hydrogen peroxide 6.6 g/L, and neutral pH. The durability and reusability of the catalytic materials were also assessed.

The Influence of Biochar Content on the Structure and Photocatalytic Activity of TiO₂/g-C₃N₄/Biochar Composite Materials

Thanh Tuoi Nguyen — 2025-03-24

In this study, the ternary composite material TiO₂/g-C₃N₄/biochar (TCNBC), derived from reed stalks, was successfully synthesized using a simple hydrolysis method. The study demonstrates that biochar has a significant impact on the structure and photocatalytic activity of the obtained composite material. Biochar plays a crucial role in inhibiting crystal growth, increasing the specific surface area, narrowing the band gap energy, and enhancing the visible light absorption capability of TiO₂. The TCNBC composite exhibits an average crystal size of 5.5 nm and a lower band gap energy of 0.62 eV, while its specific surface area (32.6 m²/g) is significantly higher than that of pure TiO₂ (33.7 nm, 3.02 eV, and 2.1 m²/g). The synthesized photocatalyst composite was used as an effective catalyst for the photodegradation of doxycycline (DC) from aqueous solutions. The hybrid TCNBC catalyst exhibited approximately 7.48 times higher photocatalytic activity compared to pure TiO₂. The TCNBC composite synthesized with a TiOSO₄/g-C₃N₄/biochar mass ratio of 4/1.5/0.5 achieved the highest DC photodegradation efficiency, reaching 91.93% within 120 minutes of visible light irradiation. These findings indicate that the synthesized catalysts hold great promise for the treatment of DC in wastewater.

Electromechanical properties of Bi(Mn1/2Ti1/2)O3 doped Pb0.94Sr0.05La0.01(Zr0.54Ti0.46)0.9975O3 materials

Van Thinh Nguyen — 2025-03-19

The solid-phase reaction technique was used to fabricate a Pb_0.94Sr_0.05La_0.01(Zr_0.54Ti_0.46)_0.9975O₃doped Bi(Mn_1/2Ti_1/2)O₃ piezoelectric ceramic system. The material's structure and microstructure were examined by using scanning electron microscopy (SEM) and XRD analysis. The addition of Bi(Mn_1/2Ti_1/2)O₃ to Pb_0.94Sr_0.05La_0.01(Zr_0.54Ti_0.46)_0.9975O₃ contributes to the transition of the tetragonal phase to the rhombohedral phase; the average particle size decreases, while the mechanical quality coefficient Q_m of the material increases. A product with a composition of 0.97 Pb_0.94Sr_0.05La_0.01(Zr_0.54Ti_0.46)_0.9975O₃ – 0.03 Bi(Mn_1/2Ti_1/2)O₃ has the characteristics of hard piezoelectric ceramic with the electromechanical coupling factor k_p = 0.59; k_t = 0.48; piezoelectric constant d₃₃ = 446 pC/N; mechanical quality factor Q_m = 774; phase transition temperature T_m = 265°C. This material exhibits properties comparable with commercial materials such as PZT4 and PZT8. This hard ceramic has the potential for use in power ultrasonic devices.