Issues: Kỹ thuật và Công nghệ cho Phát triển bền vững Vol 34.4 (10/2024)
1. Research on Eggshell Membrane Separation for High-Purity Calcium Carbonate (CaCO3) Recovery

Phan Thanh Tam, Nguyen Thi Thuy, Nguyen Hai Van*

Along with growing poultry farming, a large amount of eggshell waste is generated daily from food plants and hatcheries. This waste represents a potential biological hazard and is currently being disposed of as environmental pollution. The main composition of eggshells - calcium carbonate - can produce various types of calcium products, such as calcium citrate, calcium lactate, calcium gluconate, … which are beneficial to human health. However, eggshells contain a membrane composed of proteins like collagen and sulfur-rich proteins. These membranes have a fibrous and durable structure, making them difficult to separate from the hard shell layer. The separation of eggshell membranes facilitates the production of high-purity calcium products from calcium carbonate. This study employed three methods to investigate the separation of eggshell membranes: a chemical method using NaOH (1), an enzymatic method utilizing protease enzymes (2), and a combined chemical-enzymatic treatment (3). The results showed that the composition of the eggshells was 94.63% inorganic salts and 3.58% eggshell membranes. The membrane separation efficiency reached 90.63% within 1 hour using method (1). The membrane separation efficiency was relatively high, with Alcalase 2.5L reaching 84.75% and with Protamex reaching 75.62% after 3 hours using the enzymatic method. The combined method achieved a good separation efficiency of 95.04% within 2.25 hours, and the recovered calcium purity reached 99.69%. These results demonstrate the potential for developing an industrial-scale process to treat eggshells and produce high-purity natural calcium products as a valuable source of calcium supplementation for human consumption.

Article Code:24038

# Calcium carbonate, eggshell, eggshell membrane, protease enzymes

Page: 1-8

Field: Biotechnology and Food Technology
2. Production of Porous Silica from Rice Husk Using Cetyltrimethylammonium Bromide to Remove Dyes in Aqueous Solution

Nguyen Van Doan, Nguyen Thi Mai, Dao Thi Cam Vi, Nguyen Thu Huong, Vu Tuan Cuong, Le Trung Phong, Nguyen Thu Huyen, Vu Anh Tuan*

Porous silica was prepared from rice husk (RH) for the removal of organic dye (Janus Green B, JGB). The as-prepared samples were analyzed by using emission scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and N2 adsorption/desorption isotherm. The as-prepared silica was an amorphous and mesoporous material and the textural properties depended on the assistance of cetyltrimethylammonium bromide (CTAB). The SiO2-15 sample had a large surface area of 544.5 m2/g, a high pore volume of 1.259 cm3/g and average pore size of 9.4 nm. The performance of the SiO2-15 was evaluated by the removal of JGB and the effects of reaction parameters on the adsorption process were extensively explored. The optimum conditions for the removal of JGB were adsorbent dosage of 0.5 g/L, solution pH of 6, JGB concentration of 30 ppm, and temperature of 30 oC. The removal efficiency of JGB on SiO2-15 was 98.83% in 60 min with a rate constant of 0.025 g.mg-1.min-1. In addition, the adsorption is fast in the initial 5 min and the adsorption isotherms were investigated.

Article Code:24015

# Adsorption, porous silica, rice husks, CTAB, Janus Green B

Page: 9-16

Field: Chemical Engineering
3. Amplification and DNA Sequencing of the Nuclear Ribosomal Internal Transcribed Spacer Region from Dried Black Pepper Samples for Traceability

Truong Quoc Phong*, Nguyen Thi Thanh Nam, Hoang Quoc Tuan, Cung Thi To Quynh

Traceability is the ability to follow the circulation of a product through all steps in the supply chain. Traceability will ensure transparency of product origin and quality. Traceability involves product records and labeling. For biological samples, in addition to the commonly used management parameters, a number of specific markers will be used to control the product, such as nucleic acid (DNA), protein, carbonhydrates, etc. Pepper is a product with economic value and is grown in many different countries around the world. Pepper products from different growing regions will have different quality and prices. Tracing the origin of pepper also faces many challenges. Therefore, in this study, appropriate conditions for DNA extraction from dried pepper were determined, including extraction buffer, sample grinding method, and total DNA precipitation conditions. Appropriate conditions to carry out amplification of the internal transcribed spacer (ITS) region were also determined, including the amount of DNA template (100 ng), primer concentration (0.3 μM), primer annealing temperature (55 oC) and number of reaction cycles (35 cycles). The optimal procedure was applied to amplify the ITS region of 19 pepper samples. The ITS region nucleotide sequences of 19 samples were determined and used to build a phylogenetic tree of pepper samples from different growing regions in Vietnam. The genetic diversity of the ITS region of Vietnamese pepper was also evaluated and compared with data originating from some countries, such as Thailand, China, and the US.

Article Code:24042

# Dried black pepper, DNA sequence, ITS, phylogenetics, traceability

Page: 17-23

Field: Biotechnology and Food Technology
4. Effect of Blanching Conditions on Color, Antinutrient, Paste and Gel Properties of Taro Flour

Nguyen Thi Thuy Hong, Nguyen Thi Ngoc Han, Nhan Minh Tri*

The objective of this study was to increase our understanding taro flour quality characteristics, and their sensitivity to effects of the thermal processing. To investigate this, the variability of color values, antinutrient (calcium oxalate), paste and gel properties of dried taro flour was evaluated by blanching taro root slices at different temperatures (80, 90, and 100 °C) and durations (1, 2, and 3 minutes). Blanching temperature improved the color values and reduced calcium oxalate more than blanching duration. About 50–75 % of the variability of RVA (Rapid Viscosity Analyser) pasting properties and hardness of flour gels kept at 4 °C for 24 h was contributed by blanching temperatures. Flour gel consistency had a higher degree of variance (65 %) from blanching time, although blanching temperature also contributed significantly to variability. Raising the blanching temperature boosted the consistency and hardness of taro flour gel, but lowered its viscosity and pasting temperature. Meanwhile, extending the blanching duration heightens taro flour viscosity and gel consistency but diminished gel hardness. Viscosities was negatively correlated with gel consistency but positively with hardness. Understanding extent of the specific blanching process affecting on functional properties of taro flour is useful for food technologists to apply in foods and other applications

Article Code:24033

# Blanching, gel consistency, gel hardness, pasting properties, taro flour

Page: 24-32

Field: Chemical Engineering
5. Removal of Chemical Oxygen Demand, Colorants and Non-Biodegradable from Leachate Using KMnO4

Tran Le Minh, Vu Kiem Thuy*

Leachate is known to have complicated compositions nd hard to be treated effectively. However, the results presented in this paper show that large proportions of COD, colorants and some non-biodegradable groups could be reduced significantly at the preliminary stage of oxidation process using a strong oxidizing agent such as potassium permanganate (KMnO4). At the initial pH of 7.5, the concentrations of 10,800mg/L COD, 5,926 color (Pt-Co), 133-1,034 ppb polycyclic aromatic hydrocarbon (PAH), 7.49 – 712 ppb organochlorine compounds (OCS) and 21.54 – 2,560 ppb organophosphorous compounds (OPS) were investigated. Within 2 hours of treatment with the initial KMnO4 concentration of approximate 1 g/L and air flow rate of 5 L/minute, the removals of COD, color, groups of PAH, OCS and OPS from leachate were found to be 57%, 93% and over 90%, respectively. These results show that this oxidation process is more effective compared to the coagulation processes with iron or aluminum salts and this technique can be a help to improve the leachate treatment efficiency.

Article Code:23057

# COD removal, color degradation, leachate treatment

Page: 33-39

Field: Environmental Science and Technology
6. Detection of Nitrofurantoin Antibiotic via Electrochemical Technique Using Green Synthesized Iron/Graphene/Tetrakis (4-Carboxyphenyl) Porphyrin Nanocomposite as Electrode Material

Nguyen Thi Xuan Quynh, Cao Hong Ha, La Duc Duong, Dang Trung Dung*

Antibiotic residues are always a threat to human health. Nitrofurantoin (NFT) is an antibiotic commonly used in agriculture, which can be dangerous to human life when entering the body through antibiotic residues in food. The green synthesized iron/graphene nanocomposite has shown promising electrochemical properties as a sensor for detecting NFTs. The morphology and structure of iron/graphene nanocomposite materials were evaluated by modern analyses, including Scanning Electron Microscope combined with Energy Dispersive X-ray Spectroscopy elemental mapping (SEM-EDX mapping) and Fourier-transform infrared spectroscopy (FT-IR). The results show that iron nanoparticles with a size of 30-50 nm are evenly distributed on the graphene surface and interspersed in the porphyrin fibers. The factors of scan rate, pH, and amount of material affecting the ability to identify NFT in solution were investigated. A standard plot with a wide linear range of 1-200 µM was built to analyze NFT antibiotics. The results open up the potential for applying Fe/GNPs nanocomposite materials in electrochemical sensors to detect residues of other antibiotics in food.

Article Code:24016

# Green synthesis, electrochemical sensor, nitrofurantoin

Page: 40-47

Field: Chemical Engineering
7. A Numerical Study of Convergence Speed in Solving Stress Field by Control Volume Based Finite Difference Method

Long Trandinh*

The study presents an efficient implementation of the control volume-based finite difference method (CVFDM) integrated with a line-by-line solver for stress and strain analysis. The Navier's equation was discretized for each element, yielding fifteen displacement unknowns represented in a single equation. For this study, a three-unknown formulation per element was adopted. A line-by-line solver employing the TriDiagonal Matrix Algorithm (TDMA) was utilized to solve the equations. Dynamic memory allocation for updating displacements at previous element rows, enhancing convergence speed. Variables were solved and stored contiguously along a row in each time step, the iteration continued until the desired accuracy was achieved, eliminating the need for redundant boundary condition updates and reducing overall simulation time. A finite difference method (FDM)-based stress analysis application was developed based on the novel approach proposed in this work. Numerical simulations of three problems conducted using this application demonstrate a high level of agreement with theoretical solutions. The modified CVFDM with line-by-line solver proves to be an efficient and robust approach for stress and strain analysis, providing accurate and reliable results.

Article Code:24021

# CVFDM, stagger mesh, convergence criterion

Page: 48-56

Field: Mechanical Engineering
8. The Resilience of Supply Chain: The Case of Vietnamese Pharmaceutical Companies

Nguyen Thi Mai Anh*, Le Van Chinh, Pham Mai Chi, Vu Dinh Nghiem Hung

The COVID-19 pandemic has highlighted the crucial importance of supply chain resilience, especially in pharmaceutical companies. The disruptions exposed vulnerabilities compounded by the industry's globalized and complex nature. In Vietnam, the pharmaceutical sector is vital, serving approximately 97.33 million people. Despite significant growth, the industry faces challenges like heavy reliance on imported drugs, which make up nearly half of total consumption. The pandemic further strained supply chains, causing shortages and price hikes due to demand spikes and logistical issues.
This study explores the perceptions of Vietnamese pharmaceutical companies regarding their supply chain capabilities and competencies and their impact on resilience. Using a survey methodology, data was collected from 109 pharmaceutical companies in Vietnam through convenience sampling, considering company size, ownership, and types. The analysis involved descriptive statistics, Cronbach’s Alpha reliability testing, and multiple regression analysis.
Finding reveal that "Information System Capabilities (ISC)" and "Supply Chain Management Strategies (SMS)" significantly and positively influence both the agility and robustness of supply chains. "Risk Management Capabilities (RMC)" positively and significantly affect robustness alone. The study emphasizes the need for strategic investments in technology and risk management to enhance supply chain resilience, allowing companies to effectively handle uncertainties and disruptions while maintaining operational excellence.

Article Code:24028

# Supply chain, supply chain management, resilience, pharmaceutical companies, Vietnam

Page: 57-65

Field: Economics and Management