Issues: Kỹ thuật và Công nghệ cho Phát triển bền vững Vol 34.3 (07/2024)
1. Adsorptive Removal and Photo-Fenton Degradation of Congo Red Dye from Water Using Modified Gadolinium Orthoferrite

Thi To Nga Phan*, Thi Thu Huyen Nguyen

GdFeO3-incoporated zeolite (GFO/Z) was successfully prepared by the impregnation method followed by the calcination process and used for adsorption and photo-Fenton degradation of Congo Red (CR). The as-prepared GFO/Z material was characterized by X-ray Diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface area, and optical absorption spectra (UV-Vis). The large specific surface area and accessible pores supported its high performance towards the adsorption of CR . Besides, due to its low band gap energy, the photo-Fenton catalytic activities of GFO/Z were also investigated for the degradation of CR under visible light irradiation. The use of GFO/Z led to a high removal rate (97.46%) of CR thanks to the synergistic effect between effective dark adsorption and visible-light-driven Fenton degradation, which was greater than those of pure GFO. Scavenger experiments were performed to reveal that the hydroxyl radicals (•OH) were the main active species in the photo-Fenton catalytic process. This work showed a promising application of GFO/Z in the degradation of organic compounds in wastewater.

Article Code:24013

# GdFeO3, zeolite, impregnation method, adsorption, photo-Fenton, CR

Page: 1-7

Field: Chemical Engineering
2. Fabrication of Graphene Oxide for Application in Removing Tetracycline Hydrochloride in Aqueous Solution

Nguyen Thu Huong, Vo Quang Linh, Nguyen Ngoc Thinh, Le Dieu Thu, Tran Thi Thu Huyen, Nguyen Minh Viet, Le Van Dung, Tran Vinh Hoang, Vu Anh Tuan*

Recently, antibiotic pollution has been recognized as an aquatic environmental pollution, due to its potential adverse effects on ecosystems and human health. Therefore, it is necessary to have an effective and environmentally friendly method to remove antibiotic residues in the aquatic environment. In this study, Graphene oxide (GO) was synthesized for the treatment of antibiotic residues in the aquatic environment. The characteristics of GO material were analyzed by the X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM, JEM-JEOL 2100) methods. The GO material was used for the adsorption of tetracycline hydrochloride (TCH) in an aqueous environment. The adsorption equilibration time is 30 min and an efficiency of approximately 88.57% with an initial TCH concentration of 20 mg/L. The factors that affect the adsorption process were investigated including the initial TCH concentration (10 to 40 mg/L), the GO dosage (0.1 to 0.5 g/L), and the pH solution (1 to 9). The adsorption process of TCH on GO material is consistent with the Freundlich isotherm model with a maximum adsorption capacity of 65.65 mg/g. The TCH adsorption process of GO material is exothermic.

Article Code:24014

# Adsorbent, GO, tetracycline, adsorption isotherm, kinetics

Page: 8-15

Field: Chemical Engineering
3. Synthesis of Zero-Valent Iron Nanoparticles on Polyester Non-Woven Fabric Using Green Chemistry Method for Wastewater Treatment in the Textile Dyeing Industry

Duong Thi Hong Anh, Bui Thi Ngoc Bich, Van Dinh Son Tho, Nguyen Nhat Trinh, Dang Trung Dung*

Wastewater from the dyeing process is causing serious issues for the ecosystem and humans. Zero-valent iron nanoparticles have been proven as a promising material for environmental treatment through numerous previous studies. In this research, green-synthesized zero-valent iron nanoparticles were obtained from the leaf extract of the Cleistocalyx operculatus. These nanoparticles were then applied onto polyester non-woven fabric with alginate coating on the fabric surface. The modified polyester non-woven fabric with alginate and zero-valent iron nanoparticles (PET/Alginate/nZVI), alginate-coated polyester non-woven fabric (PET/Alginate), and the original polyester non-woven fabric (PET) were evaluated for morphology and structure using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The capability of removing the organic dye Rhodamine B was assessed through UV-Vis spectroscopy. The influence of iron dosage, solution concentration, and solution pH on the dye removal capacity of the material was investigated. Results show that the material has been successfully synthesized for high-performance removal of Rhodamine B dye with an efficiency of 98% after 10 minutes of treatment, and it can be reused multiple times with an efficiency of over 70%.

Article Code:24017

# Alginate, green synthesis, polyester nonwoven fabric, zero-valent iron nanoparticles

Page: 16-22

Field: Materials Science and Engineering
4. Some Chemical Components from Gnetum montanum Markgr. in Vietnam

Nguyen Thi Viet Thanh*, Dang Thanh Tung

Gnetum montanum Markgr.(Gnetaceae), Vietnamese name as Day gam, Gam nui is creeping and turning wood, distributed in natural forests at altitudes of 200-1200 m. It grows widely in mountainous areas in Vietnam. Its stem can disinfect, eliminate rheumatism, eliminate toxins in the body, and support the treatment of inflammation, blood disorders, leprosy, or joint pain in traditional medicine. In the course of study on the chemical composition of Gnetum montanum Markgr. in Vietnam, this paper described the extraction and structure evaluation of four compounds, including lehmbachol D (1), 3,4,5-trimethoxy-10,14-stibenediol (2), gnetucleistol C (3) and (+)-pinoresinol (4). The stems of this plant were collected, identified, dried and extracted in different polarity solvents. These substances were isolated from the ethyl acetate of methanol extract on the basis of column chromatography combined with thin layer chromatography. Their structures were identified based on spectroscopic evaluation and comparison of corresponding authentic compounds. Compound 2 was firstly recorded on the paper.

Article Code:24019

# Gnetum, G.montanum., stilbenes, stilbenediol

Page: 23-30

Field: Chemical Engineering
5. Electric-Based Heating System for Cold Start and Idling Performances Enhancement of Carburetor Engine Fueled with Bio-Ethanol

Tien Nguyen Duy, Khanh Nguyen Duc*, Truc Nguyen The

Bio-ethanol, one of the most popular alternative fuels, has been applied widely in the world to replace conventional fuel in internal combustion engines, especially in spark ignition engines. Bio-ethanol fuel is characterized by higher heat of vaporization value and low Reid vapor pressure in comparison with conventional gasoline fuel. These properties contribute to the lower temperature of the intake mixture and less effective mixture formation, which then affect engine performance, especially at cold starting and idling conditions. In this study, an electric-based heating system (EHS) was designed to increase intake air temperature, enhancing cold starting ability and idling stability. The experimental results show that, with the EHS, the cold start ability of the testing engine improves remarkably at low ambient temperature conditions. In addition, the cold idling speed of the test engine in the case of using EHS is more stable than the case of without the system.

Article Code:24008

# Biofuel-ethanol, EHS, cold start, idling stability

Page: 31-38

Field: Mechanical Engineering
6. Numerical Simulation of the Low-Reynold Flow through Tandem Circular Cylinders with the Middle Flat Plate

Van Tuyen Vu, Viet Dung Duong, Ich Long Ngo*

The paper describes an investigation of the dynamic behaviors of the fluid flow through tandem circular cylinders with a middle flat plate. A low Reynold number of 100, which originated from appropriate applications, is considered. The Lattice Boltzmann Method is used and implemented in the Direct Numerical Simulation. The numerical model was well-validated by comparing results from the literature for either a single circular cylinder or two tandem cylinders without flat plates. Consequently, the dynamic behavior of the fluid flow through tandem circular cylinders with a middle flat plate is first revealed in this study. The numerical results show that these behaviors are affected significantly by the presence of the middle flat plate. Moreover, the pattern of vortex formation is also affected considerably when this flat plate is mounted between two cylinders, and this pattern changes at the threshold value of plate size. Hydrodynamic coefficients and the Strouhal number generally decrease with the increase in flat plate size. These results are very useful in reducing the losses caused by vortex formation and increasing the fatigue durability in potential applications, such as ocean engineering and civil engineering.

Article Code:23076

# Circular cylinder, direct numerical simulation, Lattice Boltzmann Method, Low-Reynold flow, vortex formation

Page: 39-46

Field: Mechanical Engineering
7. Research on the Feet of Men with Diabetes as a Basis for Designing Shoes and Insoles

Bui Van Huan*, Le Khanh Trang

Diabetes is a dangerous chronic disease and often causes foot complications. Foot ulcers are a dangerous complication in patients with diabetes and lead to the risk of amputation. Shoes for diabetic patients play an important role in reducing the risk of foot ulcers. Therefore, diabetic patients need to use their own footwear, designed on the basis of anthropometric research and assessment of their foot complications. The article presents the method and results of measuring the feet and evaluating thier complications of 332 male diabetic patients over the age of 40. The patients' feet were measured at Khoai Chau district medical center, Hung Yen province and at National Hospital of Endocrinology. The results showed that diabetic foot complications in men with diabetes tend to get worse over time of illness. Foot complications/pathologies are the cause of differences in measurements of height, width and circumference of male diabetic foot. This difference was independent of the patient's age. According to foot complications, about 97.2% of male patients need to use “Extra Depth Diabetic Shoes”; 21.8% of patients required “Custom Molded Inlays/insoles”; and 3.2% of patients required “Custom Molded Diabetic Shoes” and “Custom Molded Inlays”.

Article Code:24005

# Diabetes, men with diabetes, custom shoes/isnoles

Page: 47-55

Field: Textile, Clothing and Leather Engineering
8. Analyzing Barriers to Reverse Logistics Systems for E-Commerce in Vietnam

Tran Thi Huong*, Ngo Thuy Dung, Pham Thi Anh Tu

Efficient reverse logistics management not only reduces costs but also plays a crucial role in creating added value for businesses and protecting the environment. The objective of this study is to explore and classify barriers and then prioritize them based on their importance using pairwise comparison methods. To this end, a two-stage mixed-methods research design was employed. The initial qualitative stage involved a comprehensive literature review to identify key themes and categorize them into five main barrier groups: government, organization and management methods, coordination in supply chain, finance and economics, and infrastructure. The subsequent quantitative stage utilized the Analytical Hierarchy Process (AHP) and Relative Importance Index (RII) to analyze and prioritize the specific barriers within these groups. The results show that the unclear organizational structure for reverse logistics activities, the lack of mechanisms and support from the government, and a lack of coordination from customers are the biggest barriers. This paper proposed solutions for the government and e-commerce businesses to eliminate barriers and operate efficiently reverse logistics systems.

Article Code:24025

# Analytical Hierarchy Process (AHP), Barriers, E-commerce, Reverse Logistics, Relative Importance Index (RII)

Page: 56-64

Field: Economics and Management